164 FUNGI. 



views of M. A. S. CErsted,* which have not since been con- 

 firmed, but which have been cited with some approval by Pro- 

 fessor de Bary, as to a trace of sexual organs in Hymenomycetes. 

 He is supposed to have seen in Ayaricus variabilis, P., oocysts 

 or elongated reniform cells, which spring up like rudimentary 

 branches of the filaments of the mycelium, and enclose an abun- 

 dant protoplasm, if not even- a nucleus. At the base of these 

 oocysts appear the presumed antheridia, that is to say, one or two 

 slender filaments, which generally turn their extremities towards 

 the oocysts, and which more rarely are applied to them. Then, 

 without ulteriorily undergoing any appreciable modifications, the 

 fertile cell or oocyst becomes enveloped in a network of fila- 

 ments of mycelium which proceed from the one which bears it, 

 and this tissue forms the rudiments of the cap. The reality of 

 some kind of fecundation in this circumstance, and the mode of 

 the phenomena, if there is one, are for the present equally un- 

 certain. If M. CErsted's opinion is confirmed, naturally the 

 whole of the cap will be the product of fecundation. Probably 

 Karsten (Bonplandia, 1862, p. 62) saw something similar in 

 Ayaricus campeslris, but his account is obscure. 



In Phycomyces the organs of reproduction have been subjected 

 to close examination by Van Tieghem,f and although he failed 

 to discover chlamydospores in this, he describes them in other 

 Mucors. In this species, besides the regular sexual develop- 

 ment, by means of sporangia, there is a so-called sexual repro- 

 duction by means of zygospores, which takes place in this wise. 

 The threads which conjugate to form the zygospores are slender 

 and erect on the surface of the substratum. Two of these 

 threads come into close contact through a considerable length, 

 and clasp each other by alternate protuberances and depressions. 

 Some of the protuberances are prolonged into slender tubes. At 

 the same time the free extremities of the threads dilate, and arch 



* (Eersted, ia "Verhandl derKonig. Dan. Gesell. Der Wissensc h," 1st January, 

 1865; DeBary, " Handbuch der Physiol. Botanik" (1866), p. 172; "Annales 

 dcs Sci. Nat." (5 me ser.), vol. v. (1866), p. 366. 



t Van Ticglicmand Le Monnier, in "Annales des Sci. Nat." (1873), vol. xvii. 

 p. 261. 



