HARDWICKE'S SCIENCE-GOSSIP, 



207 > 



As regards the first coil of mycelium, Mr. Plowright 

 writes : " I distinctly saw this curved in two 

 oospores, and I believe the mycelium comes out 

 with a curl." The same gentleman, under date 

 May 19, writes : " I saw a great many conidiophores 

 both with conidia in situ 

 and not ; most conidia had 

 fallen off; latterly I saw 

 plenty of convoluted bases.' 

 The evidence of identity 

 appears complete, and many 

 of the figures here pub- 

 lished, and others not pub- 

 lished, have been confirmed 

 by Messrs. Yize and Plow- 

 right. 



At q on fig. 11G may be 

 seen Peronospora mycelium 

 with a young plant (q 1 ) 

 growing from amongst the 

 starch of the Potato tuber, 

 the dark background show- 

 ing the cell-wall corroded 

 by the fungus, and at r a 

 similar fragment of myce- 

 lium upon the cuticle of a 

 potato-leaf : it is very com- 

 mon to see one cell of the 

 cuticle thus discoloured by 

 the corrosive mycelium, the 

 corrosion of the cell being 

 caused by the mycelium 

 passing over and upon 

 it. Both threads here 

 shown come direct from 

 last year's resting - spores. 

 At s is engraved a branch 

 of the Potato fungus, show- 

 ing the numerous parti- 

 tions with which the 

 threads are at times fur- 

 nished, and at t is a typical 

 well -grown branch of the 

 fungus, with a full-grown 

 conidium at the apex ; 

 this conidium may either 

 discharge zoospores, as at 

 v, or an irregular mass of 

 protoplasm, as at v, from 

 either of which a new plant 

 may spring, and in this 



habit the conidium agrees 

 well with the resting- 

 spore : the branch in this 

 figure is shown as con- 

 tinuous, and though furnished with the vesicular 

 swellings, no partitions are present ; the branches 

 are frequently so seen. At w is illustrated a small 

 weak plant, giving rise to a branch, which branch 



is developing into a large and strong plant : such a 

 phenomenon is by no means uncommon, and shows 

 how the fungus increases itself in every possible 

 way. I have frequently seen this secondary thread 

 branched. 



Fig. 116. Development of Resting-spores of Potato Fungus (see text). 



During the last hours of completing this, the last 

 engraving (fig. 116) illustrative of the Potato fungus, 

 a new and curious fact came to light. On examin- 

 ing the oospores in saccharine fluid, I observed some 



