166 FUNGI. 



enlarges, the wall of the arcuate cells becomes coloured brown. 

 This colouring is more marked on the convex side, and it shows 

 itself first in the cell on which the dichotomous branches are 

 first produced, and which retains the darker tint longer than the 

 other. The zone from whence the processes issue, and also the 

 processes themselves, have their walls blackened deeply, while 

 the walls of the conjugated cells, which continue to clothe the 

 zygospore during the whole of its development, are bluish-black. 

 By pressure, the thin brittle coat which envelopes the zygospore 

 is ruptured, and the coat of the zygospore exposed, formed of a 

 thick cartilaginous membrane, studded with large irregular warts. 



The germination of the zygospores in this species has not as 

 yet been observed, but it is probably the same or very similar to 

 that observed in other species of Mucor. In these the rough 

 tuberculate epispore splits on one side, and its internal coat 

 elongates itself and protrudes as a tube filled with protoplasm 

 and oil globules, terminating in an ordinary sporangium. 

 Usually the amount of nutriment contained in the zygospore 

 is exhausted by the formation of the terminal sporangium, ac- 

 cording to Brefeld ; * but Van Tieghem and Le Monnier remark 

 that in their examinations they have often seen a partition 

 formed at about a third of the length of the principal filament 

 from the base, below which a strong branch is given off, and- 

 this is also terminated by a large sporangium. 



De Bary has given a precise account of the formation of the 

 zygospore in another of the Mucors, JRkizopus nigricans, in which 

 he says that the filaments which conjugate are solid rampant 

 tubes, which are branched without order and confusedly inter- 

 mingled. Where two of these filaments meet each of them 

 pushes towards the other an appendage which is at first cylin- 

 drical and of the same diameter. From the first these two 

 processes are applied firmly one to the other by their extremities ; 

 they increase in size, become clavate, and constitute together 

 a fusiform body placed across the two conjugated filaments. 

 Between the two halves of this body there exists no constant 

 difference of size ; often they are both perfectly equal. In each 

 * Brefeld, "Bot. Unt. uber Schimmelpilze, " p. 31. 



