STRUCTURAL ELEMENTS OF THE CYTOPLASM. 1 93 



that the plastidome was therefore homologous with the animal 

 chondriome. This inference now appears to have been based on 

 inadequate evidence, and while it may be correct I prefer for 

 the present to hold the whole matter of plastid homologies in 

 abeyance pending my more extended study of moss material. 



The pseudochondriome seems to occur in the earlier androcytes 

 as a tangled mass of threads more or less encircling the nucleus 

 and to some extent the developing limosphere. Eventually this 

 material seems to spread out over the nucleus, and stretches out 

 along the length of the sperm as the nucleus itself elongates. 

 This general history and the ultimate arrangement of the pseudo- 

 chondriome in the sperm lead me to believe that this material 

 represents the chondriome of animal cells. That, indeed, the 

 superficial similarities between an animal chondriosome and a 

 plant pseudochondriosome are real, the pseudochondriome being 

 in fact the chondriome of the plant cell, as Mottier ('18) for 

 example has held, and also Guilliermond ('24) in the modified 

 sense indicated above. 



One further cytoplasmic component of a generalized nature 

 remains to be considered the central apparatus, central bodies, 

 or centrioles, often called blepharoplasts by botanists. In 

 general, plant cells are characterized by the absence of central 

 bodies, and when something similar to them does occur, there has 

 been much controversy as to whether such structures can properly 

 be homologized with the central bodies of animal cells. Sperm- 

 forming cells offer a remarkable opportunity for checking up on 

 this matter, for the reason that the relation of the tail filament 

 to the central apparatus in the sperm is beyond dispute. If in 

 plant sperms a centriole-like body should be related to vibratile 

 filaments, the conclusion that this body was a true centriole 

 would appear unavoidable. According to Allen (' 1 7) Polytrichum 

 androcytes possess a small "blepharoplast " which eventually 

 draws out into a rod-like structure applied to the elongated 

 nucleus. The two free filaments characteristic of moss sperms 

 appear to be inserted toward the anterior end of this rod, but 

 Allen was able to follow their growth only in a fragmentary way. 

 They seem suddenly to acquire a decided staining capacity in 

 their completed condition. According to Wilson ('u) on the 



