CELL MULTIPLICATION IN SUB-CUTICULA. 39! 



from it were not satisfactory. The cestode mixture, however, 

 gave excellent results. 



The stains used were the following: Heidenhain's iron-alum- 

 haematoxylin without counterstain ; safranin counterstained with 

 light green; thionin counterstained with acid fuchsin; methyl 

 green counterstained with acid fuchsin; and safranin counter- 

 stained with water blue. 



OBSERVATIONS. 



I began my study of cell multiplication in cestodes without any 

 previous knowledge of what had been done in the field of cestode 

 cytology. Moreover, I completed the study of my material 

 and drew my conclusions before I read any of the literature on 

 the subject. 



I have confined my study of cell multiplication in Dilepis to 

 the sub-cuticula. In this tissue I have searched in vain for a 

 single clear case of mitosis or amitosis. Moreover, in order to 

 be certain I had not overlooked any, I counted 10,000 resting 

 nuclei in the sub-cuticula of the neck regions of ten worms with 

 the same result. Certainly active growth must have been taking 

 place in this region, but it could not be accounted for by mitotic 

 or amitotic division. 



I have, however, observed numerous places in this region in 

 which active cell multiplication was apparently taking place. 

 Here multinucleate cells, such as shown in Fig. i, have been 

 observed. In addition to these, large protoplasmic masses were 

 present, which varied in size from that of a single cell to that of 

 perhaps fifty cells massed together. Fig. 2 shows a typical mass. 

 These masses stain rather deeply with nuclear stains, and contain 

 from one to five nuclei. 



These masses are found abundantly in the neck region of every 

 worm I examined, and occur, although less frequently, in the 

 body region. 



By reference to any of these figures it is seen at once that the 

 mass of cytoplasm is out of proportion to the mass of the nuclei. 

 Moreover, I have observed numerous lobes and occasionally 

 even entire masses in which I was unable to find any trace of a 

 distinct nucleus. Fig. 7 shows a lobe, 1 i, and Fig. 6 a mass of 



1 At focal levels other than that shown in the figure the lobe was seen to be 

 continuous with nucleate masses. 



