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thrown off. The centrosome is generally held to regulate thedivision of the chromosomes, and the cytoplasm has not beenshown to be directly concerned with heredity. If it be

urged that the same chromosomes may be lost at each fertili-sation, and that thus variation cannot result, the objectionwill be seen not to be valid when another question is con-sidered. It is granted that heredity conditions are trans-mitted and that the same happens in the case of crossings ofplants and animals. The question now arises, How is this ?We must grasp here firmly a disputed fact-viz., that theprimitive germ- and sperm-cells in the ovary and testis re-spectively, from which the gametes arise, are not derived fromthe germ and sperm epithelium (Waldeyer’s view in 1870),but arise from an early division of the early zygote, travelthrough the developing embryo, and ultimately become fixedin the genital ridge of the Wolffian body (Eigenmann, Beard,and others). They are then the primitive germ- and sperm-cells (ordinary ova and spermatozoa) and become gameteswhen the polar bodies are thrown off. Thus the gametescontain heredity determinants owing to this origin, while theview that the primitive germ- and sperm-cells are modifiedsomatic cells makes heredity unintelligible.The question of the ratios as in brachydactyly can be under

explained only by Mendelism. Mendel showed that in plantcrossings the contrasted unit-characters segregate out insuch a manner that in the second and third generations,taken together, there is a ratio of 1 : 2 : 1 in the plants.Mendel thought that this was due to a combination of thepollen grains and egg-cells giving this elementary probabilityresult, and as a plant was by him, unfortunately, consideredas a merely somatic organism in which one does not requireto recognise a propagative and somatic part a serious errorwas made. It was thus not recognised that the significanceof the first generation following in its soma one of the con-trasted unit-characters is that the 1 : 2 : 1 ratio in plantscannot be due to gametic combination seeing that the com-bination of egg-cells and pollen grains ends in a generation.The determinants of the contrasted unit-characters in crossingsreally segregate out in the zygote in the 1 : 2 : ratio andthat, is the reason why biometric measurements of stature,&c., in man and plants give some form of this curve. Whenonce we see that determinants re-arrange themselves in thezygote according to the curve of frequency we can extendthis process to the primitive germ-cells and gametes.

I hold then that the significance of the mitotic changes inthe primitive germ-cells of the early developing ovary is thatthese are producing variation of the determinants of heredityboth by the gross divisions and by a minute re-arrangementin the divided particles. Thus all the determinants are i

re-arranged by the law of frequency and not by Galton’s law,but this point would take too long to consider here. In this

way we get in the polar bodies thrown off, not always thesame determinants but different ones, and as important oneshave their chance of loss, each unit-character gets thus its

dangerous time of loss.In brachydactyly Drinkwater found the ratio in families

affected to be 50 per cent. affected, 50 per cent. non-affected.This is, I believe, explained if we suppose that the wholedeterminant for length for the middle phalanx was lost andthus it is like a head or tail result in tossing, 50 per cent. ofeach.That the variations or deformities are azctnmatic losses is

emphasised by the fact that analogous conditions explain-able on the same hypothesis-e.g., anencephaly, genitaldeformities, &c -are constantly occurring, although fromtheir nature there is no heredity-such variations are

incapable of propagation. The three deformities considered,cranio-cleido-dyostosis, achondroplasia, and brachydactyly,are thus due to a loss of the determinants of a Mendeliangroup of unit-characters at the maturation of the ovum or

spermatozoon ; they are transmitted because the primitivegerm cells are derived from an early division of the zygotewhen the determinants are causal ; and are transmittedwith a probability result, because their determinants are re-arranged in the primitive germ-cells and zygote according toa frequency law. Ordinary variations arise in this way, butgross losses in the polar bodies will give a marked variation-a mutation, in fact.

’

I have trespassed too long on your space and therefore donot consider how far Darwinism could be applied, and I havealso had to omit many details. I wish, however, to state inconclusion that I am confident the day will come when the

body of man will be considered as made up of functional andanatomical unit-characters—i.e., of Mendelian autonomousunits. In the skeleton we have three great groups already :(1) the bones developed in early endochondral ossification ;(2) those in late endochondral ossification ; and (3) those inmembrane. In the brain and spinal cord we have the corpuscallosum, which may be exactly wanting in some cases, thespinal cord, the spinal ganglia, posterior roots, and sensorynerves. In amyelia the first is absent but the others present(Oppenheim, Bruce’s translation, p. 393). In the genitalorgans similar groups can be made, while albinism, haemo-philia, and many other structures or conditions yield to thisgeneralisation and line of research. In tracing a familytree we may be able to plot out how these segregate, andultimately reach the law governing this. Whichevermechanism is the successful one in explaining evolutionmysteries, I do not believe that only one will succeed, but Ihold that one of the most important will be that muchcriticised and much misunderstood Mendelism whieh hasmade the name of Mendel as immortal as those of Darwinand Wallace. I am, Sir, yours faithfully,Edinburgh, Jan. 7th, 1911. D. BERRY HART.D. BERRY HART.

THE BOARD OF TRADE COMMITTEE ONCOLOUR VISION.

To the Editor of THE LANCET.

SIR,-I have been strongly advised to write to you withregard to the composition of the Colour Vision Committeeappointed by the Board of Trade. Though the overwhelmingmajority of experts are on my side with regard to the ex-tremely inefficient wool test used by the Board of Trade, not asingle one of those who have been instrumental in bringingabout the appointment of this committee is on it, whilst thosewho are definitely associated with the wool test very largelyform its expert opinion. The president of the old committeethat recommended the wool test is on the committee and thesecretary is a physicist who employs the condemned methodand is a strong advocate of the wool test. Twenty years agoI was appointed on the International Code of Signals Com-mittee to advise the Board of Trade as to efficient tests forcolour blindness. When the committee of the Royal Society(which, like the present committee, had a large majority ofphysicists, there being only one physiologist) recommendedthe Holmgren test, and that it was not necessary to have amedical man to test for vision and colour vision, my con-nexion with the Board of Trade ceased, my place being takenby a physicist, the secretary of the committee. Therefore,for this obviously medical duty the Board of Trade does notemploy a single medical man.

Colour-blindness is a physiological subject, and a know-ledge of physiology, psychology, and ophthalmology is

necessary for its appreciation. One of the two physiologistsappointed by the Board of Trade has, through illness, notbeen able to attend the meetings of the committee. I wouldsuggest that the number of physiologists be made equal tothe number of physicists. I have done everything in mypower to help the committee to come to a correct conclusion,and shall continue to do so. They have, however, made thisvery difficult for me, as I wished to make it a condition thatI should be present when they examined any of my colour-blind cases, men who are able to pass the Holmgren test.This they refused, so I withdrew the condition, but had theyacceded this letter would never have been written.

I am. Sir. vours faithfullv.F. W. EDRIDGE-GREEN.

The Institute of Physiology, University College, London,Jan. 3rd, 1911.

THE CHURCH ANTI-VIVISECTIONLEAGUE.

To the Editor of THE LANCET.

SIR,--As I presume the circular issued by the ChurchAnti-Vivisection League has been sent broadcast to the pro-fession, I thought it might interest your readers to see acopy of my reply to the secretary. I therefore inclose a - °

copy, and hope that if you can find room for it in yourjournal it may help to prevent some of your readers, through

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simple thoughtlessness, giving permission for their names tobe added to the list in question.

I am, Sir, yours faithfully,Liverpool, Jan. 10th, 1911.

CHARLES W. HAYWARD,Barrister-at-Law, M.D., D.P.H., &c.

[ENCLOSURE.]To the Clerical Organising See. Church Anti-Vivisection Society.DEAR Sir -In reply to your circular asking me to allow you to add

my name to a list of medical practitioners to be used by your league, Imust emphatically decline to have my name included in such list.

I am as much against unnecessary cruelty to animals as anybody, but toentirely abolish the right to try the effects of drugs, &c" upon animalswould restrict these experiments to being tried upon the human race,which is "out of the frying-pan into the fire!" The Anti-VivisectionSociety publishes posters and literature showing that the sufferings ofanimals in any experiments are equal to similar proceedings with humanbeings. This is pure dishonesty, and for the purpose of trading uponthe ignorance of the public, and raising violent prejudices foundedentirely upon ignorant sentimentalism. Animals are saved the mentaleffects, which are the greater part of human suffering.Your circular is also in very questionable taste. It asks for names of

doctors-" not for publication "-and then offers a temptation to themeaner instincts by stating " we are often asked by Anti-Vivisectionistsfor the names of Anti-Vivisectionist doctors in their respective neigh-hourhoods"! Under these circumstances the allusion to " unconsciousquackery " is humorous. Yours faithfully,

CHARLES W. HAYWARD,Jan. 9th, 1911. Barrister-at-Law, M.D., D.P.H., &c.

CHARLES W. HAYWARD,Barrister-at-Law, M.D., D.P.H., &c.

THE USE OF IODINE AS A DISINFECTANTOF THE SKIN BEFORE OPERATIONS.

To the Editor of THE LANCET.SIR,-Will you permit me to inform Mr. Willmott Evans

that he is in error in stating " the first advocate of its use inthis country was Mr. H. F. Waterhouse." My original paperwas published in the Bratish Medical Journal on August 14th,1909, several months before Mr. H. F. Waterhouse’s com-munication. I there stated that Dr. A. Grossich of Fiumehad used liquor iodi, 10 per cent. solution. So far as I am

aware, I was the first surgeon to use tincture of iodine,2 per cent. solution. May I also point out that, as I haveinsisted, shaving is unnecessary and the colour of the iodineis an advantage because it shows the limits of its

application.-I am, Sir, yours faithfully,

Jan. 9th, 1911.

J. LIONEL STRETTON,Senior Surgeon, Kidderminster Infirmary and

Children’s Hospital.

EHRLICH’S DIAZO REACTION.To the Editor of THE LANCET.

SIR,-Some remarks in your review of "InternationalClinics " on p. 1881 of THE LANCET of Dec. 31st, 1910,remind me that I made a long series of experiments withEhrlich’s diazo reaction in various diseases during the earlymonths of 1893. The article containing the results obtainedappeared in the Ind6cz-ra Medical Gazette for June, 1893. Thereaction was most marked in chronic diarrhoea and dysenteryand was seen more or less in other diseases.

I am, Sir, yours faithfully,J. H. TULL WALSH

Jan. 7th, 1911. Lieutenant-Colonel, LM.S. (retired).J. H. TULL WALSH

Lieutenant-Colonel, I.M.S. (retired).

A METHOD OF SERUM DIAGNOSIS FORTUBERCLE.

To the Editor of THE LANCET.

SIR,-I was not aware that Dr. W. d’Este Emery was alsoworking on this subject or I would have communicated withhim before sending an account of my experiments to you. Ihad no previous knowledge of work on the subject, butfollowed the principles of the Bordet-Gengou reaction.Before completing the article I looked up " Hewlett’s

Bacteriology," and found the statement that Wassermann andBruck had experimented on this subject in 1906, and thatthey appear to have failed to find tuberculous antibodies inlocalised or latent tuberculosis, but that Briick had beenmore successful with acute miliary tuberculosis in the earlystages. By the method I described these antibodies can beclearly shown to exist in localised tubercle.The first point Dr. Emery raises is the standardisation of

the fresh tubercle emulsion. My procedure has been toprepare an emulsion on the lines employed for the " opsonicindex. "gauge the strength by the appearance. This givesa rough but working standard. I do not find thatstandardisation of the emulsion is of such extreme import-ance, for I have obtained equally satisfactory results when

employing 5 c.mm., 10 c.mm., and 20 c.mm. of the sameemulsion, with 10 c.mm. of unheated and 40 c.mm. ofheated serum. But I fully agree with Dr. Emery that therecomes a point when, through an excess of the tubercleemulsion, normal human serum loses its power of haemo-

lysing sheep’s corpuscles (probably due to fixation of thecomplement).

Dr. Emery states that 1/500th dilution of his emulsionfixed the complement in one of his tubercle cases in 10minutes ; this, I think, shows that there is a large workingrange. I also agree with him that even a small quantity oftubercle emulsion decomplements to some degree normalserum, which is shown when equal quantities of normalserum and tubercle emulsion are mixed together. But whenheated serum is also employed this decomplementing is tosome extent masked, owing no doubt to the increasedquantity of sheep’s amboceptor present, intensifying theactivity of the complement. Also, whereas the loss of

complement in 5 c. mm. may be so great as to fail to

produce haemolysis, this is not the case with 10 c. mm.I find that the complement present in 2½ c.mm. isthe minimal which will produce a trace of haamo-lysis. Hence, if half the complement in 5 c.mm. ofnormal serum is deflected there will be no haemolysis,but if half is removed from 10 c.mm. there will be

heamolysis. Dr. Emery does not state the quantity of serumhe employs. The anti-complementary substances in serumappear to be removed by heating ; Nagouchi also mentionsthis point in connexion with the syphilis test. I always reada trace of haemolysis as a negative result, if the salt tube hasonly faintly hæmolysed. I also agree with Dr. Emery thatan old emulsion gives poor results ; this I think is due to thegrowth of a short broad bacillus.So as to simplify the technique, I have employed during

the last week an emulsion of tubercle bacilli in 5 per cent.carbolic and 1 per cent. salt. This I have standardised withnormal and tuberculous sera. I think that this emulsionwill keep active for some weeks. Dr. Emery records hisresults by the length of time required to deflect the com-plement, and he obtains the extremely interesting result thatthis can occur in 3-2L minutes.On Dec. 21st, 1910, and again later experimenting with

my own serum and a few other normals, ten minutes fromdrawing the blood, I found the following. 1. That from

2½ to 3 c.mm. were required to show some haemolysis, this

being complete with 5 c.mm. (0-5 c.mm. of sheep’scorpuscles). 2. That when the serum was incubated with20 parts 0-75 per cent. salt for one hour at 98° F., andthen the sheep’s corpuscles added, there was no trace ofhaemolysis with 6 c.mm. of serum, from 7 to 9 c.mm. beingnecessary to produce a faint tinge (incubated for one hourwith the sheep’s red cells). That is to say, fresh serum losesa considerable degree of hasmolysing power when warmed to980 F. for one hour. 3. That when the serum has stood forone hour over the clot the baemolysing substances appear togain stability and not to lose by warming to 980 F. Hence,the age of the serum is an important detail, serum fromthree to six hours old being the best, for though some com-plement is lost there is a marked gain in stability. Bydiluting human blood with 9 volumes of 1’5 per cent. saltclotting is prevented, and some of this plasma (equal to10 c. mm. of pure plasma) diluted with 20 parts of 1 per cent.salt and mixed with sheep’s corpuscles produced no

hasmolysis.From these experiments (though too few in number) I infer

that the quantity of complement in circulating blood is muchless than that in serum, and that clot gives to the serum somesubstances (complement or amboceptor) which increase itshæmolytic activity for sheep’s corpuscles. Dr. Emery statesthat with normal serum in the presence of tubercle emulsion

complement is absorbed in 15 to 25 minutes when warmedin the incubator. He does not mention the quantity of serumemployed, but if 5 c.mm. I can quite understand if the serumis fresh that this loss will occur with 1 per cent. salt also. Ifind that a temperature of 125° F. decomplements serum in10 minutes. In view of these latter results 1 now leave theserum and tubercle emulsion at room temperature (60° F.) forone and a half hours before adding the sheep’s corpuscles ;and, when preparing the decomplemented serum, employ atemperature of 125° F. for 10 minutes, as a greater tempera-ture and time may damage the immune bodies.As regards the immunity index, I have only put this

forward tentatively, suggesting it as some indication of