do three years training in general nursing, before taking out their midwifery course, which lasts a year. Midwifery is taught in the Chinese language by the lady Doctor in charge and the sister, assisted by Chinese Doctors. All nurses take the course. Only 6 nurses are in maternity training at the same time, and each attends at least 75 confinements (often a larger number), and makes a complete record of the cases (measurements, etc.) In the earlier years when women were unwilling to come to hospital the midwives also attended extern cases, but that part of the work has been difficult latterly owing to shortage of staff. After training, all nurses go in for the certificate of the Midwives Board (Hongkong); the examination is both written and oral, and requires a good education in Chinese. Seventy-seven women qualified as midwives and their services have proved useful; some are in Government service in Hongkong, others hold responsible positions in Hospitals under Chinese Management, a few are in the Straits Settlements, but the majority are in private practice in Hongkong. By the training of Chinese women a large proportion of the confinements in the Colony are attended by properly qualified midwives, and thus the work has been of considerable value to the community. In the training of the midwife the importance of obtaining help of a Doctor in all serious cases is emphasised, and as a result abnormal cases are seen at an earlier stage than heretofore; this is especially noticeable in such conditions as placenta praevia. As Hongkong is a long way away from the U.S.A. a little local information may be of interest. An estimate of the population of the Colony for the middle of the year 1924 was as follows: Total Chinese .... Total Population 783,550 799,550 The number of deaths of children under one year old was 4,735 Non-Chinese 37 4,698 Of these 1,131 Chinese were under 1 month old, and 7 nonChinese. The ratio of infant deaths to total deaths was 30.4 per cent. There were 8 registered deaths from puerperal fever in 1924, and 19 in 1923. There appear to have been in all 33 deaths from causes directly attributable to pregnancy. Acknowledgment Report of the Sanitary Dept. } 1924. THE ORIGIN OF CANCER. C. Y. WANG, M.D., B.SC., F.R.C.P.Ed., D.P.H., D.T.M.&H. Cancer is a neoplasm composed of cells which have acquired the power to grow in an aimless, lawless manner. In their growth they are not governed by any physiological needs of the body, and retain throughout their specific biological characters. That is, if the cells making up the tumour are derived from the skin they continue to keratinize and this feature is retained by the metastatic deposits and even through years of propagation. At no time do they show deviation from the parent cells, either in their morphological appearances or mode of reproduction. The complex nature of the cancer growth has thus given rise to the formulation of various theories to explain the causation of the tumour. These can generally be divided into two categories -the biological and the parasitic theory. Of the biological hypothesis one may mention Cohnheim's view that cancer has its origin in the embryonic "rests" which are cells capable under favourable conditions of unlimited proliferation leading to tumour formations, and Ribbert's theory that disturbance of the tissue-tension, normally maintained among the various tissue-elements may, through injury, irritation or other causes, result in isolation of groups of cells which now free from the restraining influences of their neighbouring cells will multiply to form new-growths. Such theories do not, however, explain all the known facts of cancer, and in view of the successful transplantation of cancer in a number of cases between animals of the same species are no longer tenable. The germ theory assigning the cause of cancer to a specific micro-organism is not a new one. Various organisms including yeasts, protozoa and bacteria have been described as having definite relation to the etiology of the disease, but none has been shown to withstand the critical examination of experimentation. It would appear that the wide distribution of the disease among vertebrates, as first shown by Bashford and Murray, and the non-transmissibility of the growth from one species of animal to another has to be interpreted as arguments against the supposition that an òrganism by itself can, when introduced into the body, produce all the fundamental features of cancer, in the same way as the tubercle bacillus produces tuberculosis. For applying the parasitic theory to explain all the known facts which have been demonstrated, experimentally, regarding the neoplasm one Such has to assume not only one specific organism for each species of animals but even one for each individual case of cancer. assumption is impossible. As first shown by Ribbert cancer at its inception is a local condition and if removed at the very early stage of its growth is a curable disease. Only at a latter period of its course will it become generalised by direct transportation of the primary tumour cells through the lymphatic and blood vessels. The first successful transplantation of the tumour between animals of the same species was performed by Hanan in 1888, followed by that recorded in 1902 by Jensen. These observations would have passed unnoticed but for the subsequent, work of Bashford and Murray which showed that cancer has a wide zoological distribution, being found to develop spontaneously in fishes, amphibians, reptiles, birds and mammals. What is more, the tumour bears essential similarity in the different classes of animals and the transplanted growth consists of the descendants of the original tumour cells, and is not the result of a transformation of the cells of the new host which merely supply the stroma necessary for the growth of the transplanted cells. Such was the extent of our conception of the etiology of cancer until 1911 when Rous working on fowl sarcomata discovered that some of the growths can be transmitted not only by inoculation of living tumour cells but also by a saline extract which had been rendered cell-free by a bacterial filter. Furthermore that the tumour formed by the filtrate shows a distinctive biological individuality in that the filtrate from an osteochondrosarcoma reproduces the structure of an osteochondrosarcoma and that from a spindle-celled sarcoma forms a spindlecelled sarcoma. Such observations can only be satisfactorily explained by assigning as cause of these sarcomatous tumours to a filterable agent which by reason of its being able to propagate through successive generations of artificial cultivation is in all probability a virus. Assuming this is so it would still have to explain why the virus reproduces the biological individuality of the growth. No answer was forthcoming to this question until the appearance of Gye's work which shows that two distinctive factors are concerned in the etiology of cancer-an extrinsic and an intrinsic factor. The extrinsic factor is a virus common to all tumours of different species and classes of animals and is therefore non-specific. Its presence alone is unable to bring about the malignant transformation of a cell. For it to produce a neoplasm it requires the presence of the intrinsic factor which is a substance-probably chemical in nature-produced by the cells and which acts as an adjuvant rendering the cells susceptible to the infection by the virus. This intrinsic agent is moreover specific in character as it varies from tissue to tissue and from tumour to tumour. The following is a summary of certain tentative conclusions which may be drawn from the observations recorded by Gye (Lancet, July 18, 1925). 1. Cancer is a specific disease caused by a virus or group of viruses. 2. The virus can be cultivated and probably lives and multiplies in the cells of the tumour. 3. The virus alone is ineffective. In order that it may produce a tumour a second (specific) factor obtained from tumour extracts is necessary rendering the cell susceptible to infection with the virus. 4. The virus is non-specific in character, for it has been demonstrated that a tumour can be produced in one species of animal with the virus derived from the tumour of another species. 5. The species specificity is shown alone by the specific factor which if obtained from a mouse tumour can only produce, experimentally, a new growth in another mouse, but not in an animal of other species. |