398 C. CLIFFORD DOBELL. 



forms, and to examine them after treatment by suitable cyto- 

 logical methods. 



The foregoing" considerations have led me to a study of tlie 

 cytology of tlie Bacteria. During the last four years I have 

 devoted a considerable amount of time and labour in an 

 endeavour to arrive at })ositive conclusions regarding the 

 structure of the bacterial cell. It has been my object to discover 

 large Bacteria which can be investigated cytologically with 

 comparative ease — both whilst living and after snitable fixation 

 and staining. The present paper represents the greater part 

 of the results of my work, which — though still in progress — 

 has led me to conclusions which are sufficiently definite to 

 appear to me worth publication. I do not claim that the 

 problem of the cytology of the Bacteria has been solved. My 

 results are here given merely as a contribution towards a 

 solution of the problem : I know only too well how incom- 

 plete and imperfect they are. 



My main object has been to discover whether the Bacteria 

 are nucleate or enucleate cells. It is useless to speculate upon 

 the "simplicity," " primitiveness," "lack of differentiation," 

 etc., which this important group is supposed to display, when 

 such a siinple point as this remains in doubt. I have en- 

 deavoured to find out whether a nucleus is present, and — if 

 present — what form or forms it may assume. As staining 

 reactions and micro-chemical tests appear to me to have been 

 a signal failure in this direction, I have attacked the problem 

 from another point of view — the morphological. I hoped — 

 and I confess I am not altogether disappointed — that a study 

 of the morphological elements present in the cell, and their 

 behaviour during the various phases of the life-cycle, would 

 throw considerable light upon the matter. Such results as I 

 have obtained are, at least, very definite. They are, moreover, 

 suppoi'ted by the less important — as I believe — results derived 

 from staining reactions. 



As there is already a very extensive and confusing litera- 

 ture dealing with the structure of Bacteria, I have thought it 

 advisable to give a brief historic review of the more important 



