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question, which is not finally settled, whether drugssuch as sulphonal can actually produce haemato-

porphyria, or whether they merely act as excitingcauses in persons already exhibiting the disease in alatent form. While the chronic types are relativelybenign in character, the prognosis in the acute formsis bad. No treatment appears to be of any avail, butcalcium is recommended on theoretical grounds. Theorigin of the pigments is still uncertain. The older

theory of a disturbance of haemoglobin katabolismis questioned by Fischer, whose work makes itextremely probable that neither uroporphyrin norcoproporphyrin can be derived from haemoglobin. Itwould appear that they are synthesised from ingestedpyrrole compounds, principally by the bone-marrow.This is a process which normally occurs only to aslight extent, but is much more prominent in fcetallife and in certain birds ; it probably represents astage in the synthesis of haemoglobin. The suggestionis of a reversion to a more primitive level of pigmentformation, in fact a kind of atavism. This theory,which implies perhaps the lack of specific enzymes,agrees well with the observation that congenitalhsematoporphyria is usually inherited as a Mendelianrecessive.

MENTAL DISORDER ASSOCIATED WITH

PREGNANCY

IT has generally been believed that the insanitiesoccurring in association with pregnancy have a goodprognosis, but clinical studies of any large series ofcases are hard to find. Dr. C. B. Bamford has recentlyanalysed the 97 cases admitted into the RainhillHospital between 1883 and 1933. He believes thatthese psychoses only form one-tenth of the insanitiesassociated with reproduction, and he also concludesthat in 60 per cent. of his cases some form of mentaldisability was present before conception. Of the 97cases, 25 were defectives or epileptics ; schizophrenicor manic depressive signs had already manifestedthemselves in 23 cases before the outbreak of thoseserious abnormalities for which detention became

necessary. The determination of the point at whichmental disease actually began was by no meanseasy, and it is perhaps surprising that 35 per cent. ofthe patients, including half the epileptics, made acomplete recovery. The absence in the series of anyevidence of a toxic or exhaustive factor is striking,and it points to one essential difference betweengestational and puerperal cases. In the former,constitutional factors and previous signs of faultystock are to be expected ; in the latter it is toxsemicconcomitants which are generally easy to find. Thata psychopathic inheritance was only recorded in17 cases may well be due to lack of interest in thismatter in the earlier period covered by the review ;it would be difficult to believe that unstable hereditywas present in less than 20 per cent. of these potentialpsychopaths. Dr. Bamford notes that confusionwas present in 23 of the 34 recovered cases andcompares this finding with the absence of recordedexhaustion or intoxication. It seems clear that thealtered metabolism of pregnancy precipitates mentaldisorder in suitably constituted persons as it produceseclampsia in others differently constructed. All thecases were much worse at the time of delivery andmost of them only began to improve after the secondmonth. In view of the recovery-rates, Dr. Bamfordquestions whether premature termination of thepregnancy is advisable. In the Rainhill series itwas never attempted. What is of present-day

1 Jour. of Ment. Sci., January, 1934, p. 58.

interest is the high percentage of psychopathsamong the cases, and the question of limiting fertilitynaturally arises. Whilst the prognosis appears goodit is less so than is commonly taught.

RUNNING AND WALKING

AT full speed a champion sprinter attains a velocityof 23t miles per hour, a performance which comparesnot unfavourably with the racehorse’s 36 miles perhour. It must be conceded, however, that the

quadruped maintains this speed over the Derbycourse of a mile and a half ; a runner over the samedistance would be capable of an average rate of about13 miles per hour. The fastest walking recorded,half a mile in three minutes, illustrates the compara-tive inefficiency of this method of progression. Afirst-class long distance runner can continue at thatrate for over two and a half hours. Neverthelessit is a matter of common experience that walkingis suitable for low speeds, and is indeed, up to a certainlimit, more suitable than running. But when higherspeeds are required, the muscular mechanism of thebody is adapted to run. There is a range of speeds atwhich, mechanically considered, running and walkingare equally possible, a range which is fairly strictlylimited since really fast walking demands a con-

siderable course of training and a high degree ofathletic efficiency. Within such limits it is possibleto compare the energy expenditure required in thetwo methods of progression. F. G. Benedict andH. Murschhauser (1915),1 Furusawa and others

(1924),2 basing their conclusions upon the oxygenintake during the effort, have demonstrated the

greater energy efficiency of running. RecentlyOgasawara,3 working from the department of indus-trial physiology of the London School of Hygiene, hasrepeated these investigations in estimating the oxygenrequirement-i.e., the excess of oxygen used inexercise and recovery-per minute when walkingand running at the same speed.I Ogasawara’s subject walked or ran 500 metreswhilst carrying a portable Douglas bag in which the.expired air was collected during the exercise and thesubsequent period of 40 minutes rest. He found thatwhen the rate of progression was substantially thesame, the measured oxygen required for walking wasapproximately 4 per cent. greater at a speed of fivemiles per hour, increasing to 20 per cent. at sixand two-thirds miles per hour. As Ogasawarapoints out, these comparisons of oxygen requirementper minute for walking and running are not a truecomparison of the oxygen used or required per unitmuscular movement-namely, per stride. In the caseof running, fewer movements are performed than inwalking, although the speed of progression and thetotal distance covered may be the same. Inasmuch asthe length of stride in walking is less than that inrunning, more strides must be taken to approachthe speed, and the difference in oxygen requirementappears to be directly related to the number of stridesin each case. The vigorous arm swinging movementsinherent in walking must be responsible for someincrease in oxygen requirement, and attempts havebeen made to estimate its extent by independentobservations. But as in fast walking the swing ofthe arms across the chest is an essential feature, theisolated study of this movement is without signifi-cance in the comparison of walking and running.In running, speed is an expression of length of stride

1 Carnegie Inst. of Washington, No. 231.2 Furusawa, K., Hill, A. V., Long, C. N. H., and Lupton, H.:

Proc. Roy. Soc. B, xcvii., 168, 175.3 Ogasawara, M. : Jour. of Physiol., 1934, lxxxi., 255.