124 rOTATO-FTTNGUS. 



the anthcridia in reference to their form ; though I mi;jjht object that 

 in no known Peronospora or S(q)rolegnia do the antheridia possess bo 

 regular a globular form as the bodies to which this name is given 

 in the Fungi here cited. In all known Peronoftporea and Saproleyniece 

 the antheridia are not formed until after the extremity of the branch 

 which supports them, and from which they are afterwards separated 

 by a septum, has attached itself to the oogonium, and this attachment 

 takes place in the early stage of both organs. Antheridia originating 

 freely in the surrounding space are, as regards the known forms, at 

 least a great rarity, if indeed they ever occur, but this is a point which 

 I will not here decide. Fig. 13 represents nine "antheridia"; of 

 these, two are attached to the " oogonia " ; five others, equally large, 

 rise from their pedicels, and are free in the surrounding space ; and 

 two lie beside them quite free. These phenomena entirely disagree 

 with all that is yet known of Peronosporece and Saprolegniecs. 



It is equally opposed to knowu phenomena that the " antheridia" 

 in question originate from a mycelium which is luxuriantly ramified, 

 and is throughout diflterent and indeed anatomically separate from 

 that which supports tlie " oogonia." It is true that the branches of 

 Peronosporece and Saprolegniece are often of very unequal thickness, and 

 those which support antheridia often thinner than others. But when 

 the relation between the two kinds of branches are traced, it is found 

 that those which support antheridia almost always dcvelope in proxi- 

 mity to the insertion of the oogonia belonging to them, and con- 

 sequently a special antheridian mycelium by the side of one sup- 

 porting oogonia would be an unheard-of coincidence in the familied in 

 question. 



One cannot, it is true, say that such phenomena are impossible in 

 these families. They would, however, require to be regarded as pecu- 

 liarities in the highest degree remarkable in the Potato-fungus if the 

 explanation of the doubtful organs were otherwise beyond question ; 

 taken by themselves, they not only do not confirm this explanation, 

 but go decidedly against it. 



I look in vain for other reasons in support of this explanation, or 

 to establish even its probability. Grant that those warty bodies 

 which resemble the oospore of P. Arenarm are really oospores, it was 

 surely necessary, at the least, to give a detailed account of their de- 

 velopment from the supposed oogonia and antheridia of the macerated 

 preparation in order to establish the correctness of the explanation 

 given of these doubtful bodies ; but that has not been done. 



1 have myself endeavoured to fill up this lacuna by examining pre- 

 parations of Mr. Smith's, which he has been so good as to com- 

 municate to me through Mr. Carruthers, but I have come to an opposite 

 result. The two preparations which I examined were mounted on glass, 

 and bore the inscription ^^ Pcronospora infestans, Mont. Resting- 

 spores and oogonia." Both contain, in the liquid in which they are 

 preserved, much granular detritus, obviously the product of the mace- 

 ration of the Potato ; then there are distinctly septate threads of myce- 

 lium, which, from their form, I should class with Oidiiim lactis, the 

 more so because there likewise exist in the preparations conidia of 

 this common mould, which also grows under water ; and lastly, nume- 

 rous isolated globular bladders, somewhat larger than the oogonia of 



