HARDWICKE'S SCIENCE-GOSSIP. 



1S1 



106) has produced no hybernating resting-spore. An 

 opinion has been expressed that there is no differ- 

 ence between De Bary's P. vexans and the organisms 

 described by me ; but De Bary himself says, in 

 criticising me, that I have described ' two forms of 

 fungus — both different from the Potato fungus, and 



\ D 



Fig. 106. Pythium vexans, De Bary. a, a, oogonia; b, b, 

 antheridia ; c, oogonium discharging its contents in the 

 form of zoospores ; d, oospore germinating by sending out 

 mycelium. Enlarged 400 diameters. From De Bary's 

 illustration and slide No. 8. 



possibly also from each other,' and that my resting- 

 spores may rather be compared with the 'thin- 

 walled oospores of Peronospora vilicola,' than 

 P. armaria, to which I compared them. 



Fig. 107. Peronospora in/estans. Conidiophores, repi'oduced 

 from the Gardeners' Chrunh-le, July 24, 18/5. Enlarged 

 250 diameters. 



" Pythium proliferum* De Bary, is reproduced 

 from De Bary's original plate, because Max 

 Cornu, on examining my preparations, wrote 

 me that he had seen very similar resting-spores 

 with mine in P. proliferum. This latter plant 

 is more like my organisms than either of the 

 others just described, but it differs totally in its 

 general habit and non-septate threads. Max Cornu 

 wrote me that my oogonia also reminded him of 

 those found in the genus Myzocytium of Schenk. 



* A large figure of this fungus appeared in the G'irdeners' 

 Chronicle. 



" Dr. Wittmack, together with Professor Kny, Dr. 

 Oscar Brefeld, and Dr. Magnus, all of Berlin, have 

 examined my preparations, and write of the resting- 

 spore -. 'We all don't venture to say what it is. It 

 looks so much like a Pythium, and has also so many 

 resemblances of [to] Peronospora, that without 

 studying the whole evolution, it is too difficult to 

 decide the matter. Most oospores of Peronospora 

 are a little larger , yet I find those of P. pygmcea 

 of the same size nearly as on your slide.' Unlike 

 my other critics, De Bary will not accept my obser- 

 vations; he even prints 'oogonia' and 'antheri- 

 dia" in inverted commas ; he says no botanist could 

 accept the mycelium of Peronospora as I show it ; 



Fig. 108. Peronospora infestuns. Conidiophore, from De 

 Bary, " Ann. des Sc. Nat.," ser. 4, vol. xx. pi. 5, fig. 2. 

 Enlarged 250 diameters. 



that it is better to leave my figures out of con- 

 sideration, and that I do not even accurately know 

 the conidiophores (threads which support the 

 spores). In support of the latter statement, he 

 refers to the Gardeners' Chronicle, July 24, 1875» 

 fig. 19, and says the conidiophores ' present an 

 important difference from those of the real P. in- 

 festans.' The conidiophores from that figure arc 

 here reproduced (fig. 107). A momentary view will 

 show that I never intended to illustrate typical 

 fruiting branches of the fungus, but just any such 

 accidental ill-grown pieces as happened to be on the 

 preparation. But if these two outlines are to con- 

 clusively show my ignorance of the conidiophores 

 of the Potato fungus, what are we to say to De 

 Bary's own figure— also here reproduced, fig. 108, and 

 taken from the 'Annalesdes Sciences Naturelles,' 

 series i, vol. xx. plate 5, fig. 2 ? If one figure is 

 correct, the 'important difference ' of the other is 

 not very apparent, especially when the conidio- 

 phores were not described by me at all, but a refer- 

 ence was merely made to the secondary condition of 

 the Peronospora. 



