POLYTOMELLA CITRI, SP. NOV. 221 



mitosis, there is some substance of the nature of oxychromatin 

 that is dissolved and passes through the nuclear membrane. 

 This would make the cytoplasmic area under discussion corre- 

 spond to the archoplasm of Boveri and the archiplasm of Conklin 

 and Wilson. There was no indication of granules of chromatin 

 going bodily through the nuclear membrane. 



Encystment. When the cell enters encystment the cellulose 

 wall is evidently formed very rapidly. Only a few individuals 

 were found that did not have a perceptible membrane and in these 

 cases it was only a matter of several hours until they looked quite 

 old and sturdy. While the cyst is still spherical the starch bodies 

 are well under way to disappearance (Figs. 26 and 27). W 7 hen 

 the wrinkling of the cyst has reached the degree which typically 

 makes the general outline triangular the starch is all gone. 

 Observation of many stained sections of early spherical cysts did 

 not reveal any remnant of the basal granules. 



As soon as the organism has become encysted the region im- 

 mediately surrounding the nucleus becomes filled with spherical 

 bodies which are more basiphilic than the nucleus itself. These 

 bodies increase in extent with the aging of the cyst and soon come 

 to fill the entire cell. In many cases the nucleus, which has now 

 decreased to half its original size and stains very faintly, is 

 obscured. Unless a study of this stage is made very critically one 

 might be led to believe that the nucleus has broken up to form 

 chromidia. Such is not the case. Whenever the knife cut 

 through the nucleus or near it the karyosome, anchoring strands, 

 and nuclear membrane make a perfect miniature, in both size and 

 staining character, of the nucleus of the active form. In the 

 hundreds of such sections examined there was no suggestion of 

 chromatin particles leaving the nucleus. Since this material does 

 not come from the nucleus and stains more deeply with haema- 

 toxylin, Bonney's triple stain, and methyl green than does 

 chromatin the name metachromatic granules is justified. It is of 

 interest that the increase of metachromatic granules is highly 

 correlated with the disappearance of starch. 



After remaining in this condition for some time the granules 

 gradually drain out of the central part of the cell and collect 

 around the periphery, mostly in the angles. The previous 



