N0.460.] STUDIES ON PLANT CELL.— V. 239 



esting account accompanied by clear figures gives an explanation 

 far more in keeping with what we know and might expect of the 

 behavior of chromatophores in resting spores. That the green 

 chromatophore may temporarily become much modified in color 

 and form is well known in some of the red and orange resting 

 spores of the Volvocaceae and the zygospores of the desmids. 

 In some of these types the form and color of the chromatophores 

 become quite lost for the time being so that studies on their 

 behavior are very difficult. For these reasons it seems probable 

 that the accounts of the fusion of the chromatophore in the zygo- 

 spore of Spirogyra are incorrect. It is very interesting that the 

 gametes of Spirogyra should be so sharply differentiated that the 

 chromatophore of one should be reduced during conjugation in 

 a manner that resembles very closely the behavior of the chro- 

 matophore in highly differentiated sperms. 



There is no evidence that the pigment spots, so generally 

 present in the motile gametes of lower forms, ever unite. They 

 have been followed into the zygospore and after the germination 

 of this cell and they remain entirely independent of one another 

 as would be expected from their close relationships to chromato- 

 phores. 



The fate of the blepharoplast will now be considered. This 

 structure is especially' interesting because of its close analogy to 

 the locomotor apparatus of the animal spermatozoon, which is 

 formed chiefly from one or more centrosomes generally with the 

 cooperation of archoplasm (idiosome, Nebenkern). It is also 

 claimed by a number of zoologists that in some forms, at least, 

 the centrosomes of the first cleavage spindle are derived from 

 the spermatozoon. 



All evidence indi9ates that the blepharoplast of the plant 

 sperm is left behind in the cytoplasm of the egg when the male 

 nucleus passes into the interior to unite with the female and 

 that centrospheres when present, in the first cleavage spindle, 

 are formed de novo. The fate of the blepharoplast is clearly 

 known in Cycas (Ikeno, '98b), Zamia (Webber, :oi) and Ginkgo 

 (Ikeno, : 01). Soon after the large top-shaped sperm of these 

 forms enters the egg, the male nucleus slips out of the spiral 

 blepharoplast, that partially invests it, and, leaving it with 



