468 <'. CLIFFOKD DOr.ELL. 



from giving a satisfactory interpretation — simply to misuse 

 words, Tliat Bacteria are composed of a substance similar to 

 cytoplasm may readily be granted ; but to say that tliey 

 consist of cytoplasm is merely to use the woi-d " cytoplasm" 

 in a sense which is not generally accepted. Hence, if it were 

 proved — which it is not — that Bacteria were "cells" without 

 a nucleus, it would be necessary to employ some other word 

 than cytoplasm to designate their contents — for instance 

 Van Betieden's term " plasson," or souie such word. At 

 present, however, there is no necessity to follow such a course. 

 If one chose arbitrarily to call nucleus cytoplasm, and cyto- 

 plasm nucleus, one could easily make the astounding gene- 

 ralisation that cytoplasm Avas really not cytoplasm, but 

 nucleus. Such, it seems to me, is the method of reasoning 

 which is occasionally applied in considering the structure of 

 Bacteria. 



In addition to the foregoing considerations, I should like 

 to emphasise another point. It is sometimes stated that the 

 Bacteria show a peculiar kind of protoplasmic organisation 

 in which nucleus and cytoplasiu are not yet differen- 

 tiated from one another — that Bacteria show, in fact, a 

 primitive type of structure. Now it has never been ]iroved 

 — and indeed the evidence is against it — that Bacteria 

 possess such a structure. It is obvious, therefore, that 

 the assumption of a condition supposed to be primitive 

 cannot be used as an argument in favour of the primitiveness 

 of the group — as is sometimes done. 



Having said so much with regard to the nucleus in general, 

 I will pass on to an application of my reasoning to the 

 experimental results. 



I shall begin with a consideration of the Coccus forms of 

 Bacteria. I have shown that certain Micrococci and 

 Sarcinaa contain, in each cell, a single, centrally placed 

 spherule. This body is a morphological feature common to 

 every cell. When the cell divides,, the spherule also divides 

 — its division preceding that of the cell as a whole, and being 

 characterised by the formation of a dumb-bell-shaped ligure 



