330 ON GROWTH AND OVERGROWTH 



that is, when the syncytial cells are actively performing their 

 functions of absorption and excretion, but afterwards, when 

 these same cells, not having been shed, are left in the condition 

 of gaining nourishment — of being stimulated from without also — 

 and of having no opportunity to perform their normal functions. 

 Under such conditions microbic products might favour overgrowth. 

 It will be seen that the two statements are not contradictory. 



But is it necessary to call in micro-parasites to explain the 

 aberrant growth ? There, I confess, looking at the matter in 

 the abstract, I feel more than doubtful. For, in the first place, 

 it will be seen that this assumption — and remember that it is 

 still only an assumption, and that, consequently, one is permitted 

 to discuss it in the abstract — this assumption demands that 

 microbes of one or other order have the peculiar power of so 

 acting upon the cells of one organism — the embryo or foetus — 

 that they invade the tissues of another organism — the mother. 

 Our knowledge of the phenomena of transplantation and im- 

 plantation shows that it is not necessary to call in such external 

 agencies. That micro-parasites should have this power is, to 

 say the least, unexpected. At most we must admit that it is 

 remotely possible. 



In the second place, one of the favourite arguments of those 

 who hold parasitic theories is the similarity or analogy between 

 the local growth and metastases of malignant neoplasms, and, in 

 the case of bacterial infection, the primary focus of infection, its 

 local extension and metastatic, granulomatous, or abscess develop- 

 ments. Undoubtedly the parallelism is close, so close that 

 we may admit parasitism as the active agent in both conditions. 

 Indeed, these syncytiomas demonstrate most convincingly why 

 this is so. Bacteria are, we know, the causative parasites in 

 the one : what these syncytiomas show, and show without 

 possibility of denial, is that the trophoblastic cells — the tumour 

 cells — are the parasites in the other. They are cells of foreign 

 origin ; it is they that invade, they that gain entrance into the 

 blood-stream, that get carried to remoter parts of the organism, 

 and there set up degenerative and reactive processes, and so 

 bring about a condition of affairs resembling what is seen when 

 bacteria are the invading agents. The tumour cells are the 

 parasites ; and if we admit this — and we must admit it — then the 

 analogy becomes absolutely valueless as an argument in favour 



