68 THE NATURAL HTSTOEY EEYIEW. 



and the small clavate cells to be antheridia. The spore- cells in their 

 early stage exhibit an accumulation of granular matter in their 

 interior, not at first clothed by a membrane. As soon as this ball 

 of granular matter is formed, the antheridium emits a delicate pro- 

 longation (similar to those of the antheridia of Saprolegnia) which 

 pierces through the wall of the oogoniam, and reaches the granular 

 ball. The latter then becomes immediately clothed with a delicate, 

 colourless membrane, and thus forms an oospore. The contents of the 

 prolongation are similar to those of the main body of the antheridia, 

 and no traces of spermatozoa are visible. He then describes the 

 production of the outer membrane of the oospore of P. alsinearum^ 

 which is formed from the surrounding plasma within the oogonium. 



Pringsheiin*s Jahrbiicher flir wissenschaftliche Botanik, Vol. ii., 

 contains some observations by Hofmeister, with regard to what he 

 considers indications of sexuality in Tiiber. He noticed that the 

 terminal cell of the delicate threads which surround the ascus in 

 Tuber, and which appeared to him to spring from the stalk of the 

 ascus, became firmly united to the outer membrane of the ascus 

 itself. At the point of junction, and sometimes at other points also, 

 he observed a depression in the membrane of the ascus ; and he 

 suggests the possibility of the terminal cell being, in fact, an 

 antheridium. In the Selecta Eungorum Carpologia,* the MM. 

 Tulasne, in noticing these observations of Hofmeister, say, " We 

 " remember, whilst studying the Truffles, having often observed 

 " very delicate filaments which adhered so pertinaciously to the asci 



" that it was difficult to detach them what these fila- 



" ments were, we did not then imderstand, we now agree v>ith 

 " Hofmeister in looking to Saprolegniaf for an explanation of the 

 " phenomenon." He Bary, in his recent work — " IJeber die Prucht- 

 entwickelung der Ascomycelen" — suggests doubts as to the sexual 

 nature of the threads in Tuber ; but although his doubts may be 

 valid, his reasons for them have not been considered conclusive. J 



Eurther indications of sexuality have also been suggested by He 

 Bary as occurring in Erysijphe cicJioracearum, HC. In his work just 

 mentioned — " Ueber die Eruchtentwickelung der Ascomyceten" — 

 he traces the origin of the perithecium of ErysipJie ciclioracearum, 



* Vol. i. p. 176, 177. 



f As to Supvoleonia, see the latter part of this Report. 



X Sec Nat. Hist. Rev. Vol. iv. p. 231. 



