Contributions to the Biochemistry of Growth. 



239 



It is, of course, tempting to refer these differences to differences in the rate 

 of growth. But such a conclusion can only be based on a systematic series of 

 analyses carried out with different strains, and with the same strain at 

 different periods of its growth. Such observations are now being carried out 

 by one of us (W. E. B.). 



When we compare the lipoids of tumours derived from different tissues — 

 namely, a rat sarcoma with a mouse carcinoma — we find very marked 

 differences, both quantitatively and qualitatively. The amount of total 

 lipoids present in the sarcoma does not differ very markedly from that 

 present in the carcinomata, especially when we take into account that the 

 analyses refer to two different species. But there is a complete change in 

 the proportion in which the various lipoids are present. While in the two 

 carcinomata the bulk of the total lipoids is made up of ordinary non- 

 phosphorised fats, and phosphorised fats are present only in relatively small 

 amounts (from 7 to 10 per cent, of total lipoids), the phosphorised fats of the 

 sarcoma represent almost 40 per cent, of the total lipoids and equal in 

 amount the ordinary non-phosphorised fats. Cholesterin is present in 

 quantities similar to those found in the slowly growing carcinoma, while 

 cholesterin esters are absent both in the sarcoma and in the carcinomata. 

 Perhaps the most interesting feature is the presence in the sarcoma cells of 

 definite amounts of cerebrosides (2 per cent, of dry tissue). These lipoid 

 substances are completely absent from the two mammary carcinomata which 

 we have analysed, and the question arises, whether this qualitative chemical 

 difference is typical for carcinoma and sarcoma, or whether it is exhibited 

 merely by individual tumour-strains. This problem, again, must remain a 

 subject for further inquiry. 



Summary, 



The cells of different strains of transplantable tumours show quantitative 

 and qualitative differences in the various groups of lipoid substances present. 

 Such differences exist not only between tumour-cells derived from different 

 tissues — namely, a sarcoma and a carcinoma, but also, although not to the same 

 extent, between two different strains of tumour-cells derived from the same 

 tissue — namely, a slowly growing and a rapidly growing mammary carcinoma. 



Necrotic tumour-cells show a great increase in the amount of total lipoids 

 present, the increase being due mainly to an increase in ordinary non- 

 phosphorised fats. 



The expenses of this research were defrayed by grants from the Moray 

 Fund of the University of Edinburgh. 



s 2 



