348 WOOLFORD B. BAKER. 



This system is based on a study of Amoeba and hence could 

 scarcely be expected to apply to other forms equally as well. 

 Euglena agilis seems at first sight to fit into type one or promi- 

 tosis, and yet the division center cannot be definitely located 

 within the endosome. 



Alexeieff (1913) elaborates a system of classification which goes 

 into great detail, but which even so, does not cover all cases. 

 According to his system, Euglena agilis seems to show haplo- 

 mitosis, since no centriole can be positively identified and yet 

 distinct polar masses are formed. 



Prophase. The formation of chromosomes in Euglena agilis 

 does not occur as was described by Tschenzoff for E. viridis. In 

 the resting stage the chromatin is arranged in masses, frequently 

 dumb-bell shaped, along an achromatic network. In the early 

 prophase these separate masses appear to enlarge and increase in 

 staining capacity, at the same time fusing along the linin threads 

 of the network to form chromosomes. Tschenzoff describes the 

 formation of a number of granules around the periphery of the 

 nucleus which eventually become arranged in rows or files. 

 These become the chromosomes. It is an easy matter to make 

 out granules around the periphery of the nucleus in E. agilis at 

 this stage, but upon close examination they prove to be optical 

 cross sections of chromosomes. Also, the granules of the motor 

 complex may be found in a similar position, staining with the 

 same intensity as does the endosome. 



I have not been able to make out the beaded structure of the 

 chromosomes, such as have been figured by some investigators. 

 It is true that each chromosome appears to consist of two masses 

 in its earlier stages of formation and later these masses seem to 

 run together to form the smooth chromosome. It is difficult to 

 interpret this apparent double structure of the chromosomes. It 

 is possible that it represents a doubling or splitting at some 

 previous stage in the cycle. Wenrich describes such an ap- 

 pearance of chromosomes in Trichomonas and traces it back to a 

 constriction in the previous anaphase. He does not connect this 

 constriction with the split chromosomes of the prophase however, 

 nor does he attach any particular importance to the phenomenon. 



Kofoid describes a pseudo-reduction of chromosomes in 



