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difficult problem. The maximum number is put underguardianship, but many respectable working-classpeople have been driven by the trade depression toseek relief in respect of a defective child, who wouldotherwise not have sought help. A proportion ofdefectives are unsuited for boarding-out-beingeasily led into crime, inebriety, prostitution, &c.--but these should be given a trial, for under properguardianship good habits may be acquired in youth.The higher-grade defective appreciates freedom, butguardians must be carefully selected, especially withregard to the sexual risk in the case of young females.In relation to the selection of guardians, Dr. Gibsonreports that he has formed a very favourable idea ofthe sense of responsibility of, and care exercised by,’theaverage guardian, and urges that something be doneto prevent the gradual decrease now apparent in thenumbers of those willing to preserve the successfulScottish method of dealing with the insane poor.

THE CERCARIAL FAUNA OF INDIA.

THE elucitation ot the ine-nistories ot the ctlgenetlctrematodes, since the discovery of the life-cycle ofFasciola hepatica by Thomas in 1881, has alwaysexercised a fascination for medical zoologists ; andthe most recent contribution is in the form of anillustrated supplementary issue of the Indian Journalof Jledical Research, entirely occupied by an articleby Major R. B. Seymour Sewell, I.M.S., entitled" Cercariee Indicae." The works of Sonsino andLooss (1896) were directed primarily to the eluci-dation of the life-cycle in Egypt of SchistosomaAcBMMoMMMt, the most noxious of all trematodesaffecting man; during their researches they dis-covered and described numerous cercariae or larvaltrematodes in the fresh-water molluscs they dis-sected ; but, failing to trace them to their matureor parental forms, they were led to allocate themgeneric rank, to which descriptive specific nameswere attached. Ltihe (1909), in the course ofsimilar researches on the cercariae of fresh-watersnails in Germany, drew up a provisional classifi-cation of these cercarise on a morphological basis.The next important advance was the determina-tion in 1914 of the cercarial stage of Schistosomajaponicum by Miyairi, Suzuki, and Ogata, a discoverywhich was almost immediately confirmed and ex-

panded by Leiper and Atkinson and finally completedby the former during his studies in Egypt, wherebythe existence of two species of schistosomes infestingman in that country was established, and the life-histories traced through two different species ofintermediary molluscan hosts and back to the definitivehost again. The mainspring of this work was thedifferentiation and recognition of the furcocercous orfork-tailed cercarise as the larval stages of the Schisto-somidee from among the multitudinous cercariseinhabiting fresh-water molluscs. These researchesimparted a fresh stimulus to the whole subject, andled to the work of Cawston in South Africa and thecareful and intricate morphological studies of Fauston the cercariae of that country, as well as those ofNorth America, a subject upon which Cort has alsoconsiderably expanded our knowledge.The dangers arising from the possible introduction

of schistosomiasis into India from troops returning tothat country who had become infected during theirterm of service in Egypt led to the study of thissubject being undertaken by Kemp and Gravely, ofthe zoological survey of India. They found there,as had the several workers already mentioned in theirrespective areas, that they had entered upon a

vast and hitherto unexplored field of zoologicalresearch, in which new forms of cercariae were

continually presenting themselves. This subject hasnow been taken up by Major Sewell, the writerof the absorbing article under notice. One ofhis first discoveries was that of a fork-tailed cercariain Indoplanorbis exustus and Limincea acuminatacorresponding exactly to the description given byCort for Schistosoma japonicum, though the mature

form of this parasite is not known to occur in India.Still further researches have led to the production ofthis important work, in which are described andfigured 57 cercarise of the fresh-water snail fauna ofIndia, wherein a definite system of classification isbased upon their outstanding morphological features,but no attempt has been made to allocate generic orspecific rank to hitherto undescribed forms. On theother hand, this worker relies for his identificationupon their tabulation with definite numerals, beingrightly adverse to the bestowal of specific names uponlarval forms. Such a study is beset with manydifficulties, by no means the least being the uncer-tainty whether all cercarise can be separated upon ananatomical basis. Though the vast majority ofknown cercariee can be assigned to groups or sub-groups, we have no direct evidence that these groupsnecessarily correspond to various genera or sub-genera of the scheme of classification adopted for theadult trematodes. The majority of the fresh-watergastropods of India were found to harbour variouscercarise, and the species found most frequentlyinfected and apparently capable of acting as primaryhost to a large number of trematode species are

Melanoides tuberculatus with 17 forms, and Indo-planorbis exustus with 15. The number in which thecomplete life-history is worked out is extremely small,and consequently the known adult forms are few.This is hardly to be wondered at considering theintricacy of the problem.The possible definitive hosts in any particular case

may be birds, reptiles, mammals, batiachians, or

fish, all of which are parasitised by trematodes. Manyof these hosts are migratory, and may be infectedduring a short sojourn in India, so that it may be con-fidently predicted that many years will elapse beforethis subject is finally elucidated. As it is, helmin-thologists will be led to concentrate more upon life-histories than upon morphological features of theadult forms. This is a field which as yet has hardlybeen touched. Surveys of the cercarial fauna on thesame lines as set forth in this monograph should beundertaken in all parts of the world, and their resultscompared. The immensity of the field may be gaugedwhen one realises that Major Sewell has as yet derivedhis material from a comparatively small part of India.A critical survey of this important work will rest withthe systematic zoologist, but of the permanent valueof such a contribution to medical zoology there canbe no doubt.

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THE FUTURE OF THE TUBERCULOSIS COLONY.

Two reports have just appeared synchronously, andas they represent different and, in some respects,opposite views, they give each other perspective andtogether form a useful contribution to the vexed

problem of the tuberculosis colony. The first report!deals with the Papworth Hall Colony, which hasrecently enlarged its sphere of activities by theaddition of 28 new cottages designed for patients andtheir families. When they are completed the totalnumber of houses for ex-patients will be 50. Theaverage number of patients in residence during theyear under review was 168, reaching 175 in December.In 1921, 273 patients were admitted, and it will thusbe seen that the number of patients who yearly leavethe institution for some reason or other is considerable.This does not, however, necessarily reflect on themanagement of the colony, for there must be manyundesirables of the tip-and-run stamp and others towhom the colony idea is distasteful, or for whom thesponsors of the colony have no taste. The majority ofthe patients were sanatorium failures, and some nowearning their living in the colony had been driftingfrom one institution to another for years. With one ortwo possible exceptions, no early cases were admittedin 1921, the overwhelming majority being representedby patients with advanced disease. The report

1 The Cambridgeshire Tuberculosis Colony. Report of theExecutive Committee for 1921. Printed by Papworth Industries.Pp. 34