RESEARCHES ON THE MUCORINI. 65 



Phycomyces nitens from all others which are at present known. 

 The previous connection of the two conjugating hyphae and 

 their terminal curvature in the form of a vice grasping the 

 zj'gospore can only he compared with the arrangement in 

 Plptocephalis which Brefeld has made us acquainted with. 



The mode in which the processes are developed indicates 

 that there is a difference in the age and properties of the two 

 teeth of the vice, similar as they appear in other respects, and 

 similar as are the conjugating cells. We may trace in this 

 dissimilarity a first step in the differentiation of the two ele- 

 ments whose union forms the germ-cell, an indication as yet 

 feehly marked, but still very distinct, of sexuality in the 

 process of conjugation. 



We have not yet succeeded in making these zygospores 

 germinate ; but it is probable that the process is similar to 

 Avhat takes place in the case of zygospores of which we know 

 the mode of germination, especially those of Mucor fusiger 

 and M. Mucedo. We were the first to describe the zygospores 

 of this last plant. ^ A short time after we discovered their mode 

 of germination. Brefeld has also recently figui-ed and described 

 these organs and their germination.^ We shall not touch on 

 this point, therefore, except to detail some new observations. 

 The black membrane, which is generally regarded as belong- 

 ing to the zygospore, of which it forms the exospore, is really 

 absolutely foreign to it, since it is nothing more than the 

 original cell-walls of the cells which have conjugated. This 

 black membrane ruptures in germination. The thick, black, 

 cartilaginous, colourless, tubercular coat splits also on one 

 side, and its delicate internal coat elongates itself externally 

 as a tube which is filled with protoplasm and oil-drops ; it 

 is covered in its lower third with granules of calcium oxa- 

 late, while it is smooth higher up ; it attains a height of 

 three centimetres, and terminates in an ordinary sporan- 

 gium. Thus, the zygospore produces directly, not a myce- 

 lium, but an asexual reproductive apparatus. The axis of 

 this apparatus — that is to say, the axis of growth of the new 

 individual plant, is perpendicular to the line joining the 

 centres of the two conjugating cells — that is, to the coales- 

 cent axes of growth of the two sexual branches. Tn the 

 zygospore, therefore, the protoplasm has, so to speak, a 

 polarity {est orietite), the direction of which is at right angles 

 to the line joining the centres of the two conjugating masses 

 of protoplasm, or oospheres. It is also probable that each 

 oosphere is polarised in a direction at right angles to the 

 > ' Coraptes Rendus/ Ap. 8, 1872, vol. hxiv, p. 1000. 

 ' • Bot. Unt. ub. Scbimmelpilze,' p. 31, pi. ii. 



VOL. XIV. NEW SER. B 



