IIG 



rOTATO-FUNODS. 



remained liealthy they sent out many alioots, mostly healthy, but 

 also some affected by the Fungus, which will afterwards be described. 

 They were examined one by one, according to their different stages, 

 the last on the 5th of July, with the result that the phenomena 

 already described presented themselves successively in the interior. 

 Oospores were not found. Other Fungi, not belonging to Fhyto- 

 phtJiora, were often found growing abundantly in the collapsing 

 watery-tissues ; animals of the kinds already mentioned and infusoria 

 were also observed. 



6. A great abundance of Fungi was developed in the tissues of the 

 outer portion of the I'otato, which are known to resist decay very 

 long, but which were discoloured by Phitophthora. The Fungi were 

 developed while the tubers were still in the ground. These Fungi 

 were chiefly of the kinds that have long been known to attack sickly 

 tubers, such as Fusisporium and Spicaria ; it has also been long known 

 that these have no morphological relation to Fhytophthora. But in 

 several tubers which had sprouted in the ground, and were very much 

 collapsed in the interior, there was found, not only in the experiments 

 made in 1874, but also this summer, in the discoloured tissues con- 

 taining Fhytophthora, a form of Fungus, the first sight of which 

 showed that it must be either a Feronospora or Sciprolcgnia, with 

 oogonia, antheridia, and oospores (see fig. 6). The suspicion readily 



Fig. 6. 



Pythium vexans, De Bary. 1. A mycelium-tubo with two oognnia (ti and b) 

 almost mature, with antheridia, n. In a the attachments of the oofj;onium and 

 antheridium are not seen, being behind ; in h the insertion is somewhat oblique. 

 Magn. 600 diam. 2. Germinating oospore sending out mycelium. 3. The 

 same forming zoospores. 2 and 3 a little less magnified than I. 



suggested itself that the organs of Fhytophthora which had been so 

 long looked for were at last found. However, in this case a closer 

 examination showed that this was a mistake. It will, however, be 

 instructive for my purpose to enter here into some details. The pre- 

 sumed oospore-heariug Fungus was found, as has been said, in the 



