204 



HARDWICKE'S SCIENCE-GOSSIT. 



floats within from side to side, as the object hap- 

 pens to be moved under the microscope. J shows 

 the contents of oospore being broken up into zoo- 

 spores; k. shows the zoospores within still more 

 clearly, and where they are giving an echinulate 





.0, 







H 



Fig. 113. Various stages in the Development of the Resting Spore of Potato Fungus 



appearance to the bladder within (an appearance 

 adverted to lately by Mr. Berkeley) ; l shows the 

 bladder from within the oospore being discharged 

 from the oogonium after the manner of Cystopus, 



with the contained zoospores: this bladder fre- 

 quently breaks up into dust, as at m, setting the 

 zoospores which are at present quiescent free, as 

 at N ; two tails shortly appear on these latter bodies, 

 and at a certain period of their growth the anterior 



cilium, or tail, is pushed 

 straight out, as seen at 0; 

 the posterior tail then 

 quivers with an undulatory 

 movement, and the zoo- 

 spores sail out of the field 

 of the microscope. How 

 long the zoospores live it is 

 difficult to say, but probably 

 somewhere between twelve 

 hours and a week ; at length 

 they come to rest, as at p, 

 when the tails fall into fine 

 dust. Some zoospores burst 

 and at once perish, as at q, 

 whilst others throw out 

 threads of mycelium, k, 

 which threads are destined 

 at length to bear the 

 conidiophores of the Potato 

 fungus in its new genera- 

 tion. The zoospores thus 

 obtained were planted on 

 the foliage, and upon thin 

 slices of potato supplied 

 from a frame by Mr. Alfred 

 Smee. On these materials 

 they at once produced 

 mycelium and small coni- 

 diophores, which, without 

 doubt, belonged to Perono- 

 spora ; but as better results 

 were afterwards obtained 

 from resting-spores similar 

 to 1, fig. 113, the figures are 

 not here engraved. 



The Rev. J. E. Vize, Eor- 

 den Vicarage, Welshpool, a 

 gentleman who has made a 

 special study of microscopic 

 fungi, has had some of my 

 living material under exami- 

 nation during the past win- 

 ter and spring, and when the 

 first signs of germination 

 showed themselves in my 

 oospores, I wrote him to 

 keep a good look-out for 

 results. He wrote me as 

 follows, under date of April 

 21 :— " My idea certainly is that the oospores are ger- 

 minating : bottle No. 1 had a thin film on it which 

 developed into a lot of mycelium and threads of Pero- 

 nospora." I, too, observed the same fact in London. 



