POTATO-FUNGUS. 



123 



fig. 13, p. 69, of *'Gard. Chron." [Journ. Bot., p. 340, fig 2],* for 

 fig. 9, p, 68, of the same, and also the figure on p. 397 of the 

 "Journal of the Royal Agricultural Society," represent things which 

 on the face of them show that the preparation could not possibly have 

 had the appearance given to it in the illustration. It will, therefore, 

 be better to leave them out of consideration, especially as, in regard 

 to the question at issue, I should adduce the same objections against 

 them as against fig. 13. 



The principal objections are the following: — Fig. 13 represents 

 two kinds of mycelium threads — thick ones and much thinner ones — 

 which are in local, but not in anaiomical relation to each other. Tint 

 extremities of the branches of both kinds support globular cells rich 

 in protoplasm ; larger ones (m) on the thick, and smaller ones (n) 

 on the thinner threads. The former are called " oogonia " ; their 

 protoplasm afterwards withdraws from the original wall, and collects 

 itself into a globular cell enclosed within a special membrane, the 

 " oospore." The globular cells on the thin threads rise mostly free 

 in the surrounding space, many even lie there separated from their 

 pedicels ; some are attached to the " oogonia," and on this account 

 they are called " antheridia." The interpretation expressed by these 

 names is based on their supposed similarity to the oogonia, oospores, 

 and antheridia of other Fungi, say of Peronospora, which are accu- 

 rately and definitely known. But on closer examination one sees that 

 there is very little similarity. The form, perhaps the structure also, 

 of the " oogonia " may correspond, but these are unimportant, since 

 they suit also the reproductive cells of different morphological value, 

 in a variety of Fungi, as already shown. The same may be said of 



* For the convenience of our readers we here reproduce the figure in question, 

 in order that Prof, de Bajy's criticisms may be more readily ft)llowed. — [AV. 

 Journ. Bot.l 



