HARDWICKE'S SCIENCE-GOSSIP. 



205 



Throughout May the habit of the oospores ap- 

 peared to remarkably change, for instead of pro- 

 ducing zoospores they protruded a thick and 

 generally jointed thread, this thread agreeing 

 exactly in size with average Peronospora infestans 

 threads. On May 13th I 

 observed on the prepara- 

 tions treated with ex- 

 pressed juice of horse- 

 dung threads similar to the 

 very long branched thread 

 shown at s, s, s, fig. 114 ; 

 these threads were so long 

 that they traversed the 

 entire slide, and I could 

 only detect a single septum 

 or joint, and frequently 

 none, t, tj, v are charac- 

 teristic : the latter shows 

 two septa, which is a 

 common condition at this 

 stage of growth ; and all 

 three figures show the pro- 

 toplasm of the oospore 

 coiled up within the walls 

 of the latter, w shows an 

 oospore germinating with 

 the antheridium (a) 

 attached to the oogonium, 

 and still upon its last year's 

 thread ; x is a germinating 

 oospore with a thread 

 showing the first septum ; 

 and Y shows two germi- 

 nating oospores emerging 

 from one oogonium, each 

 thread showing the first 

 •septum ; the old male 

 •organ (antheridium) is still 

 attached to w, x, and y. 

 The figure at z, drawn on 

 May 12, is characteristic, 

 and shows three septa ; the 

 specimen was sent on to 

 the Rev. M. J. Berkeley, 

 who feplied: "I found 

 the germinating oospore 

 exactly as you figure it. 

 There can be no doubt 

 about the matter." Mr. 

 Broome, who was examin- 

 ing similar material of his 

 own, wrote on May 4 : "It 

 only remains now ap- 

 parently to see the Perono- 

 spora arising from the threads which proceed from 

 the oogonia to prove the identity " ; and again on 

 May 20 : "I do not see any attached conidia, but 

 the space between the sections of potato is covered 



with long threads resembling the conidiophorous 

 threads, but I could not see any with the spores on 

 them." It may be said here that no other known 

 fungus has conidiophorous threads similar to those 

 of the Potato fungus. 



Fig. 114. Development of Resting-spores of Potato Fungus. (For details see text.) 



At the beginning of May, whilst observing the 

 habit of Pusisporium and its resting state, I ob- 

 served typical Peronospora infestans growing upon 

 the drier parts of the previous year's crushed and 



