RESEARCHES ON THE MUCORINI. 63 



astonishing if one compares it with the conditions of the 

 inedium ordinarily aifected by the plant, since nothing can 

 be more different than a mass of some greasy substance and a 

 drop of our saline solution. 



In orange juice, which is evidently more nutritious, the 

 mycelium developing at first moi'e vigorously, fructifies rather 

 later, about the third day; but the branches first formed 

 are stronger, taller, and the sporangia larger, although having 

 wholly spherical spores and a depressed columella. Just as 

 with the saline solution a progressive increase takes place, 

 and the last hyphse which form in the moist chamber in 

 Avhich the growing cell is placed attain a length of as much 

 as ten centimetres. 



Sexual reproduction ; Zygospores. — In the cell-cultures, no 

 doubt owing to the unsuitableness of the medium, and even 

 on fruit in pan cultivations, we have failed to obtain the 

 sexual apparatus. On crushed cochineal and on cochineal dye, 

 on the contrary, we have repeatedly obtained it in the greatest 

 abundance. The mycelium produces at first its forest of 

 sporangiferous hypha?, shining and iridescent. If, when new 

 hyphae cease to be developed, we remove the whole of this 

 forest of hyphse, we see on the surface of growth large black 

 grains, which catch the eye at a first glance on the red back- 

 ground: these are the zygospores. It is easy then to meet with 

 them in all the states of development about to be described. 



The hyphse which conjugate to form the zygospores are 

 slender and stand erect on the surface of the substratum; they 

 are analogous to the hyphse forming the tufts which we de- 

 scribed in the cell-cultures. Two of these hyphse come into 

 close contact through a considerable length, and dovetail 

 with one another by alternate protuberances and constric- 

 tions. Some of the protuberances are frequently prolonged 

 into slender tubes (fig. 4). At the same time the free 

 extremities of the hyphse dilate and arch one towards 

 the other until their tops touch, forming a kind of vice, of 

 which the teeth rapidly increase in size. Each tooth forms 

 a partition which cuts off a cell, at first hemispherical 

 (fig. 5), and afterwards becoming cylindrical by pressure 

 (fig. 6). In each of these discoid cells the protoplasm 

 aggregates itself into a mass. The double membrane at the 

 point of contact is absorbed, and the two confluent masses of 

 protoplasm form a zygospore, which is invested with a tuber- 

 cular coat, and enveloped by the primary wall of the two 

 conjugating cells (figs. 10 and 11). 



While this is taking place the two arched cells develope 

 on the zone adjoining the walls which separate them from 



