CHYTRIDIALES 95 



sarcoptoides the nuclear membrane begins to disappear at the poles 

 at anaphase but remains present longer in the equatorial region. No 

 stages of telophasic reconstruction of nuclei were observed. 



After repeated nuclear divisions (Fig. 7 F-J) the sporangial contents 

 underwent cleavage independent of the activity of the division spindles. 

 In living material the stages preceding this process were accompanied 

 by an increase in the number of certain small refractive globules and 

 just prior to cleavage these aggregated to form the larger definitive 

 globules of the zoospores. Following this aggregation the contents 

 divided. 



Progressive cleavage, with the furrows more common at the periph- 

 ery than in the interior, then took place (Fig. 7 K), and resulted in 

 the development of many uninucleate segments. 



Although no evidence of them was seen either before or during 

 cleavage, nuclear caps were present in the fully delimited zoospore 

 initials (Fig. 7 L). In some germinating zoospores traces of the cap 

 were observable; others had no sign of it, suggesting that its material 

 disperses during germination. 



With respect to germination of the uninucleate resting spore (Fig. 

 7 M-Q), which functions as a prosporangium, Antikajian comments 

 that nuclear division does not occur within the resting spore proper. 

 Rather, the nucleus passes out of the spore into the germ sporangium 

 during germination and remains undivided as the sporangium develops. 

 Then follows a series of successive and synchronous divisions, whereby 



Explanation of Figure 7 



A-B. Young thalli developing from zoospore cyst. C. Young sporangium 

 showing large primary nucleus. D. Early prophase of primary nucleus. E. 

 Metaphase of primary nucleus. F. Binucleate sporangium. G. Late prophases 

 in multinucleate sporangium. H. Metaphases of sporangial nuclei. /. Ana- 

 phase nucleus showing chromosomes and nucleoli. /. Anaphase nuclei in 

 sporangium. K. Sporangium showing cleavage of contents. L. Sporangium 

 with fixed and stained zoospores. M. Uninucleate resting spore. N. Ger- 

 minating resting spore with prophase nucleus. O. Binucleate germinating 

 resting spore. P. Polar and profile views of metaphases in sporangium of 

 germinating resting spore. Q. Mature sporangium from germinated resting 

 spore. 



(Antikajian, 1949) 



