296 



NA TURE 



[JULV 27, 1905 



enormous strides, and it may be said that no region 

 of the body is now beyond surgical interference. 

 Many more obscure conditions, therefore, come under 

 observation than formerly, and the vast majority of 

 tumours removed bv the surgeon are in the present 

 day examined microscopically and their nature ascer- 

 tained without doubt. In the Registrar General's 

 Report for 1903 (p. 63), the various corrections which 

 have to be made to obtain even an approximate 

 corrected rate will be found. It is also to be noted 

 that the deaths classed under "ill-defined causes," 

 which doubtless included many crfses of obscure malig- 

 nant disease, have steadily faHen. Of 49.555 deaths 

 from ill-defined causes in 1903, further inquirv showed 

 that 439 were due to malignant disease. If these in- 

 quiries had not been made, which was formerly the 

 case, these 439 deaths would have been omitted, and 

 the cancer death-rate would have been correspondingly 

 •diminished. The statement is definitely made in the 

 report of the Imperial Cancer Research Fund just 

 issued that it is not yet possible to determine statis- 

 tically whether cancer has really increased. 



Cancer attacks rich and poor alike, and the manner 

 in which it progresses to a fatal issue, unless early 

 treated by radical operation, has caused it to be 

 regarded with dread by all. It attacks all races of 

 men, though the savage races seem less susceptible 

 than the civilised, and it is met with throughout the 

 vertebrate kingdom. There is no evidence that any 

 form of diet or mode of life conduces to cancer-form- 

 ation. _ The origin of cancer has for long exercised 

 the minds of pathologists, and it is in particular the 

 true cancers or epithelial tumours which have been 

 the subject of most research. 



The alleged causes of the origin of cancer may be 

 divided into cntogenous or intrinsic, spontaneous and 

 anomalous changes within the organism, and ecto- 

 genous or extrinsic, derived from outside the body. 

 Of the entogenous theories the most important are 

 those of Thiersch and of Cohnheim. Thiersch 

 suggested that tumour formation consisted in a loss 

 of balance between the epithelial cells and connective 

 tissue, whereby the former take on abnormal and un- 

 ■directed growth. Cohnheim referred the origin of 

 cancer to embryonic cells which had for some un- 

 known reason remained in an undeveloped state and 

 become included in the tissues, and which subsequently 

 proliferate and form the primary growth. Ectogenous 

 theories ascribe the formation of malignant growths 

 to the action of micro-parasites, and bacteria, veast 

 and other fungi, and protozoa have in turn been re- 

 garded as the causative organisms. There are, it is 

 true, some analogies between certain microbic con- 

 ditions and cancer formation, but the fact that it is 

 •a portion of the original growth conveyed by the blood 

 ■and lymph to distant parts which causes the secondary 

 growths, and that the tissues at the site of the 

 secondary growth take no part in its formation, is 

 quite different from what obtains in microbial affec- 

 tions. Attempts have been made to prove that cancer 

 is contagious, and it is known that the disease is 

 more prevalent in certain districts than in others, 

 which lends some support to the parasitic theory. 

 Auto-infection undoubtedly occurs ; a cancer of the 

 breast may infect the neighbouring arm, or of a 

 lip the other lip, and cancer of mice can readilv be 

 inoculated into other mice, but these instances of ap- 

 parent inoculation are rather of the nature of a 

 transplantation ; in the mouse it is the tissue intro- 

 duced which increases and forms the malignant 

 growth, not the tissue of the inoculated animal. Ex- 

 periments by the staff of the Imperial Cancer Research 

 Fund prove that healthy mice kept in close contact 

 with cancerous mice never contract the disease. 

 NO. 1865, VOL. 72] 



The cancer of one animal is inoculable only into 

 another animal of the same species, and human 

 cancer, therefore, cannot be transmitted to the lower 

 animals. ."Ml attempts to isolate a micro-parasite have 

 proved failures, in spite of the vast amount of work 

 done in this direction. The alleged organisms of 

 cancer, such, for example, as certain yeast fungi, 

 have, it is true, been found to produce tumour-like 

 growths, but these have, on critical examination, been 

 proved to be of the nature of granulomatous growths, 

 and not true cancer. .A point of which a good deal 

 has been made by the supporters of the parasitic 

 theory is that the so-called " cancer bodies." the 

 alleged parasites, are present only in malignant 

 growths, and not in normal or pathological tissue nor 

 in benign tumours. But the deduction from this fact, 

 that these bodies are therefore parasitic, has little 

 to support it when it is considered that cancer is a 

 unique tissue, and might obviously contain structures 

 not found elsewhere and not necessarily parasitic. On 

 these and other grounds the parasitic theory has of 

 late steadily been losing ground. 



The remarkable observations of Prof. Farmer and 

 Messrs. Moore and Walker have recently thrown much 

 light on the possible nature of the cancer process, 

 .^s detailed in these columns (February 4, 1904, 

 p. 319), it is found that in cancerous tissues manv 

 at least of the cells divide in a manner quite 

 different from that of the somatic or body 

 cells generally. TViis mode of cell-division observed 

 in cancer is that which obtains in gametogenic 

 or sexual reproductive tissue, and is character- 

 ised by a difference in the mode of division (trans- 

 verse instead of longitudinal) and in the number (six- 

 teen instead of thirty-two for man) of the chromatin 

 bands or chromosomes of the nucleus, and is known 

 as " heterotype mitosis." The division succeeding the I 

 heterotype, known as the homotype, still retains the | 

 reduced number of chromosomes, and is, therefore, 

 sometimes termed " reduction division." Cells with 

 reduction division do not seem to be able to regain 

 the somatic mitosis except by fertilisation. This 

 gametogenic-like tissue of malignant growths has 

 been termed "gametoid. " Other irregularities in 

 division of cancerous cells also occur. 



Another remarkable fact recently demonstrated bv 

 Messrs. Farmer, Moore, and Walker (N.ature, June 

 15, p. 164) is that in the normal reproductive tissues 

 structures occur which are strikingly similar to the 

 bodies (" cancer bodies ") described by Ruffer, 

 Plimmer, and others in cancerous growths, and 

 regarded by many as parasites. These structures 

 in the reproductive tissues are the archoplastic 

 vesicles, and that similar structures should occur 

 in cancerous growths (and not, be it noted, in benign 

 tumours) on the one hand lends additional support to 

 the idea of the gametoid nature of the cancer cells, 

 and on the other further disproves the supposed 

 parasitic nature of the "cancer bodies." 



Is it possible from these observations to formulate 

 a suggestion as to the nature of the cancer process? 

 Prof. Farmer himself has stated that he and his co- 

 workers do not profess to explain the relation between 

 the heterotype mitosis of the gametoid cells of cancer 

 and the life-history of cancer. It might be that the 

 gametoid cells of the malignant growth undergo some 

 process of fertilisation giving rise to an aberrant 

 embryo, as it were, which by development forms the 

 primary growth, which would thus be parasitic on 

 the host, the secondary growths arising from a repeti- 

 tion of the primary event. In some plants game- 

 togenic tissue may normally possess parasitic char- 

 acteristics. There is, however, so far little evidence of 

 fertilisation or fusion of the gametoid cells in cancer, 



