502 H. MAESHALL WARD. 



forthwith, after separation from the parent, or after a long dor- 

 mant period; but they also often emit zoospores while still 

 attached to the parent hypha. I have carefully followed the 

 phenomena of this process, and select fig. 17 as affording suffi- 

 cient illustrations of the details. The formation of the zoo- 

 sporangium requires no minute description (a to d). The 

 zoosporangium (e) was completely formed, and separated 

 by a septum as figured, at 12.25, and remained in pretty 

 much the same condition until after 3 o'clock ; at 3.35 several 

 vacuoles were observed, slowly changing their positions in the 

 very granular protoplasm (/). Shortly afterwards, the spor- 

 angium remaining attached, the beak was formed, and by 

 4.30 (fig. 17, g) was completed. During the next ten minutes 

 the processes of formation of the zoospores figured in fig. 16 

 took place as already described, and the zoospores became 

 developed in the gelatinous vesicle at the apex of the beak (i) ; 

 the rupture of the vesicle, and escape of the reniform bi-flagellate 

 zoospores took place as before, and at 5.5 the only remains of 

 the vesicle were attached to the end of the empty beak {k). 



Meanwhile, shortly after the passage of the protoplasm 

 through the beak into the vesicle, the septum separating the 

 zoosporangium from the hypha became protruded into the 

 cavity of the former (i), and soon attained a considerable 

 development as a vesicular swelling, in which the granular 

 contents of the hypha were slowly accumulating {k). From 

 5.40 to 6.20 (k and /) this went on gradually and continu- 

 ously, until a new sporangium had become formed in the 

 cavity of the old one. In this instance, the new zoospor- 

 angium ceased to develop during the night; but in other 

 examples it followed the usual course. This proliferation of 

 the hypha is the characteristic which gave P. proliferum its 

 excellent specific name. It is very common to find the second 

 zoosporangium thus developed into the old cavity, where it 

 forms the beak and large central vacuole before passing into 

 the dormant state, behaving as before on the renewal of favor- 

 able conditions. The beak of the new sporange is not 

 always coincident with that of the older one, and may stretch 



