322 



Mycologia 



swelling of this jelly that ejects the spores from the sporangium.'^ 

 Very often the spores do not come out, but either emerge 

 through short individual tubes as in Dictyuchus, or sprout at once 

 into hyphae as in Aplanes/ In fig. 7 the spores are emerging 

 simply through holes ; in fig. 8 they are escaping through tubes of 

 considerable length. Some were seen in the act of escaping in 

 both of these cases. ^ The passage of the protaplasm through the 

 opening is at first very slow, but when about half way through 

 the flow becomes much more rapid and the escape quickly follows. 

 When free the spore scarcely shows any motion for several 

 minutes, only a barely perceptible and uncertain rocking. Soon 

 the motion becomes more active and in about five or ten minutes, 

 depending on the temperature, the spore swims briskly away. In 

 the case shown in fig. 7, the spores before emergence contained a 

 good-sized vacuole. At the moment of complete emergence this 

 vacuole became suddenly much smaller, probably by contracting 

 and discharging as in the case of Amoeba. This was clearly dis- 

 cerned a number of times under the high power. The little 

 depauperate sporangia shown in figs. 7 and 8 were formed imme- 

 diately from spores sprouting in a large sporangium. When a 

 small insect was placed near them, the end cell was sent out as a 

 long and very delicate hypha that reached the insect and pene- 

 trated it. The spores in the sporangia were in a resting condition, 

 but when deprived of air by being covered with a glass for a 

 while, the spores began to emerge as shown. By this method 

 sporangia of Dictyuchus and other species that have been resting 

 for some time may be made to empty themselves whenever 

 desired, as I have repeatedly demonstrated. 



The oogonia are racemosely borne on straight or bent branches 

 that vary greatly in length. Sometimes they are not one half as 

 long as the diameter of the oogonia ; again they may be four times 

 as long. These extremes in length are rare and they usually vary 

 from about one and one half to two and one half times the 



^ For Humphrey's argument against the mechanical expulsion of the spores 

 in Achlya, see his Saprolegniaceae of the United States, page 66. 



' Such variations occur in most of the species of Saprolegniaceae that I have 

 studied. See Lechmere. The New Phytologist 9: 308. 1910; and 10: 167. 191 1. 



*This phenomenon was also observed for this species by Ward. See Quart. 

 Journ. Micro. Scien. 23 N-S : 272. 1883. 



