498 H. MAESHALL WARD. 



into the surrounding water and form racemose systems of 

 branches; the ends of the main, secondary, and tertiary branches 

 then swell up as before into ])yriform or oval zoosporangia, 

 each of which becomes cut off by a septum, and then commonly 

 puts forth a short necklike process or beak before it separates 

 and falls from the plant (fig. 11). The formation of this beak 

 may, however, be deferred until after the dormant period. 

 The branch, at the end of which such a sporangium has arisen, 

 then frequently puts forth a lateral branchlet beneath the 

 sporangium, the latter thus appearing to be placed laterally 

 on the hypha (fig. 11). 



The fallen zoosporangium may either remain dormant for 

 weeks or months or germinate at once ; its behaviour in this 

 respect apparently depending simply on the fitness of the 

 environment: germination, or the formation of zoospores, is 

 not, however, necessarily preceded by the falling of the 

 sporangium, as will be seen in examples to be studied imme- 

 diately. 



In fig. 11^ are depicted zoosporangia which had been kept 

 dormant many months in a cool cellar; the thick outer wall, 

 short beak-like process, and large central vacuole are character- 

 istic. INlingled with these one often observes oospores and 

 empty zoosporangia (fig. 12), the necks of the latter having 

 become prolonged and open to admit of the emission of the 

 contents; soon after adding fresh water to sporangia in the 

 condition shown at fig. 11^, very many of them become thus 

 emptied of their contents. Others, however, instead of be- 

 coming thus emptied germinate in the ordinary manner by 

 throwing out a simple tube as in P. De Baryanum. I have 

 carefully observed both processes. 



The zoosporangium (fig. 13 a) was drawn at 12.30, several 

 hours after the addition of pure oxygenated water; from the 

 condition shown in fig. 11^ the contents had not much changed 

 excepting that the vacuole had become broken up into several 

 smaller ones distributed in the active granular protoplasm; the 

 beak, which was not formed immediately after the separation 

 of the sporangium, now commenced lo appear as a faint 

 papilla, laterally situated near the point by which the spo- 



