56 VAN TIEGHEM AND LE MONNIER. 



shown that it only occupies a small part of this r>pace, and 

 projects externally. The zygospore is therefore, like the 

 asexual spores, endogenous in its origin. 



It does not germinate till it has undergone a desiccation 

 and has experienced a certain period of rest. Placed in a 

 moist atmosphere it produces at once, without the inter- 

 vention of mycelium, a sporangial system possessing all the 

 characters which belong to that of the species which pro- 

 duces it. The asexual spores which these contain develops 

 a mycelium, in their turn producing sporangia, chlamydo- 

 spores, and zygospores. 



In the actual state of our knowledge it is difficult to affirm 

 that all these kinds of reproductive apparatus exist in every 

 representative of the group. In point of fact, only one — the 

 sporangial — has been observed in all the species. Zygospores 

 are only at present known in the genera Sporodinia, Rhizo- 

 pus, Mucor, Phy corny ces, ChcBtocladium, and Piptocephalis. 

 Brefeld does not admit that Chcetodudium and Piptocephalis 

 possess sporangia, but only conidia. According to his views, 

 therefore, the term Zygotnycetes is more expressive than 

 Mucoritii, wdiich he restricts to the sporangiferous Zygomy- 

 cetes. This, however, appears to us founded on an error, 

 and there appears, therefore, no reason for changing, on this 

 ground, the old and .established name of the group. 



PiLOBOLUS. 



J. Klein ^ has been led, owing to a faulty method of obser- 

 vation, to the erroneous result that Piloholus is capable of con- 

 version into Mucor. It is quite true that he sowed the spores 

 on a slide, but he used a drop of fruit juice covered with a piece 

 of thin glass, and it was on the uncovered edges of the drop, 

 exposed to every source of error and inaccessible to rigorous 

 examination, that he observed the development and fructifi- 

 cation of Mucor. 



It is rather remarkable that the suspicions of Klein were 

 not aroused by the unexpected nature of his results. Thus 

 the spores of P. crystallinus sown in a watchglass produced 

 a Mucor with sporangia. Spores of the same crop of P. crys- 

 tallinus sown in horse-dung decoction produced the fructifi- 

 cation of P. crystallinus. Spores of this second generation 

 sown on saccharine fruit juice produced, in their turn, a 

 Mucor, but one different from the first. We therefore arrive 

 at the result, not a little surprising, that Pilobolus-s])ores 



^ " Zur Kenntniss des Pilobolus," ' Pringsh. Jahrb. f. w. Bot.,' viii, pp. 

 362—372. 



