RESEARCHES ON THE MUCORINI. 69 



under this form that Thamnidium was discovered by Link, 

 which explains how this author came to describe the spo- 

 rangia as spores. 



Cell-culture has shown that, on the first appearance of the 

 mycelium, there are innumerable transitions between the two 

 forms of sporangia sown in a cell; in ordinary water the, 

 spores did not germinate ; in the saline solution, on the 

 contrary, they germinated, but their hyphse speedily became 

 empty, owing to the protoplasm concentrating itself at 

 certain points and forming isolated chlamydospores, but not 

 producing fructification. In horse-dung decoction and orange 

 juice, on the contrary, it succeeds well. 



The oval spore at first swells, becomes spherical, and 

 continues to increase for some time ; then, without the least 

 trace of a ruptured exospore, it puts out one or two hyphae, 

 Avhich ramify progressively, and form here and there on its 

 principal ramifications attenuated branches, divided into 

 tufts of radicles, and separated from the main branch by a 

 partition near their base. After forty-eight hours the 

 mycelium thus formed has produced in the air within the 

 cell a large number of erect sporangiferous branches. They 

 bear sometimes a single sporangium, variable in size (fig, 18, 

 a, g), spores of which may, if the nutrition be insufficient, be 

 reduced to two or even a single one, sometimes two or three, 

 or four to thirty-two or more sporangia (fig. 18, b, c, d, e). 



In proportion as the dichotomy increases, the size of 

 the sporangia and the extent to which their septum 

 bulges iuAvards decrease, and finally they only have four 

 spores. The earliest fructification produced by the young 

 mycelium presents all possible transitions between the two 

 kinds of hyphae and sporangia. Amongst these transitions 

 small sporangia without a columella terminate simple hyphse, 

 and large sporangia with a distinct columella terminate 

 dichotomies, in which case the spores are often very unequal 

 in size ; and all these transitions occur not only on a 

 mycelium, which is the product of numerous spores, but even 

 upon that which is derived from a single one. One branch of 

 a mycelial hypha, for example (fig. 19), will produce a single 

 large sporangium, while another will terminate in a system 

 three times dichotomous with eight moderate-sized spo- 

 rangia. 



We have also observed on the branched hyphse horizontal 

 branches, usually also dichotomous, develope with or without 

 a septum, and bearing sporangia both smaller and more 

 numerous than those of the terminal dichotomy (fig. 19). lu 

 such cases it often happens that when the sporangia of the 



