POTATO-FUNGUS. 



121 



sufficient evidence to prove that they are sexual organs or oogonia. 

 There is no reason whatever to consider them as belonging to the 

 Potato-fungus, unless we base it on the fact that I found them close to 

 that Fungus in the course of experiments in search of its oospores. 



It is impossible to assign its systematic position to the Fungus 

 which bears the star-shaped bodies, owing to our defective knowledge 

 of its development. It, however, received a name, if I am not mistaken, 

 more than thirty years ago. In 1845, or perhaps earlier, Montague 

 found, in a sprouted, but not diseased, Potato, a Fungus which he 

 called Artotrogus hydnosporus, and of which Mr. Berkeley* published 

 a short description and engraving in 1846. A dried original specimen 

 of Montague's which I have examined presents the following cha- 

 racters : — On a sheet of mica is an entirely colourless section of a 

 Potato, dried up, the walls of the cells mostly quite empty, but some 

 still retaining starch grains. Many slender threads of Fungus, in which 

 for the most part no distinct structure can, be any longer recognised, 

 pass through the preparation, and there are besides numerous globular 

 bodies of two kinds abounding in protoplasm strewn over it. The one 

 kind cannot with certainty be distinguished from those star-shaped 

 bodies I have described, in which the prickly envelope is entirely filled 

 by the smooth globule. They present no oi'ganic connection with the 

 other forms of Fungus, but lie free amongjthem. Montague draws 

 them as isolated organisms, both in the sketch published by Berkeley, 

 and in another which he sent me in 1863. In the second place, the 

 preparation exhibits globular or oval cells with very dense protoplasm, 

 which are somewhat larger in diameter than the prickly one, and are 

 always distinctly supported on septate Fungus threads, mostly inter- 

 calated, seldom apparently terminal. The wall of these cells is in 

 many cases moderately thick ; in others it appears to be very thick, 



shining, and gelatinous. The 

 granular protoplasm is sur- 

 rovinded, at least in the moist- 

 ened specimens, with a broad, 

 shining, colourless border, which 

 I can regard only as such a 

 membrane (see Fig. 8). Mon- 

 tague and Berkeley have ex- 

 plained the globular cells of both 

 kinds as exhibiting progressive 

 steps in their development, the 

 smooth ones being the younger. 

 For this no reason is given, nor 

 have 1 found any in the renewed 

 examination of the specimens. 

 And one can scarcely conceive, 

 from the known phenomena 

 of development, how the 

 smooth thick-walled cells could 

 become the smaller star-shaped 

 ones. But thefactis, that we have 

 here two forms of Fungus, which 



Fii?. 8. 



Smooth globules on thin mycelium 

 threads, from Montague's original speci- 

 men of Artotrogus. Magn. 375 diam. 



" Journal of the Horticultural Society," i., p. 27, pi. 4. 



