358 BOTANICAL GAZETTE [November 



elongated basal cell. This condition occurs particularly on young 

 plants started on agar and subsequently transferred to water. If 

 sufficient moisture is present the same thing may take place directly 

 on the agar (figs. 4, 5). Zoosporangia may be produced singly or 



in 



The growth of the plant is rapid when the best external condi- 



tions are offered. Observations made relative to this 

 that in one case hyphae which were just emerging f 



day 



which 



with 



material 



Development of zoosporangia 



asm 



The zoosporangia are broadly oval to almost spherical, rarely 

 elliptical, smooth, hyaline, and fairly constant in form and size. 

 They may originate terminally or subterminally on the branchlets. 

 In the former case the first indication of such a development is a 

 slight swelling of the hyphal end accompanied by a well marked 



(fig. 11, a-c). Before reaching its normal 

 size, the zoosporangium becomes cut off from the hypha by a 

 septum, and papillae of dehiscence begin to appear. When pro- 

 duced subterminally, the mature zoosporangium may be borne on 

 a more or less elongated branchlet, as previously noted, which 

 originated from the parent branch directly below another repro- 

 ductive body (fig. 6) , may be sessile (fig. 12, b) , or even develop as 

 swollen segments cut off by septa (fig. 12, a). The latter method 

 when continued produces a chain of zoosporangia (fig. 59)- As a 

 result of cutting off the ends of fertile branches, zoosporangia may 

 bud out from the remaining parts in various places. In certain 

 instances the contents of the injured branches give rise to zoospores 

 without any modification in form. 



The zoosporangia of B. Pringsheimii, after discharging their 

 zoospores, drop from the plant, leaving numerous scars. This was 

 noted by Thaxter (9) and also by Petersen (4) • I have never 



observed this Dhenomenrm to taVf r»larp in E straneulata. Old 



