MODERN RESEARCHES INTO THE NATURE OF YEAST, 155 
the intermediate portions of the mycelium remaining empty, 
and the resting-spores do not become detached. 
These bodies have long been known; Berkeley described 
them as long ago as 1838,! and Zabel and Bail’ subsequently, 
giving them the unfortunate names “‘ gemme,” “ Kugelhefe,” 
and ‘ Gliederhefe.” Bail refers them to Mucor, which is, 
however, in his view identical with Saccharomyces ; Hoffmann 
described them as “Mucor-hefe,” distinguishing them from the 
ordinary yeast which according to him was derived from 
Penicillium; De Bary and Woronin referred them to Mucor 
Mucedo and racemosus ; Reess and Fitz to M. Mucedo only. 
Brefeld points out that the division of the originally uni- 
cellular mycelium of Mucor by septa is a phenomenon com- 
mon to all the species when the mycelium is sufficiently 
large, the only difference in the case of M. racemosus being 
the great number of these septa, and the consequent very small 
size of the sporangiophores ; the resting-spores being produced 
only when the formation of the sporangiophores is rendered 
impossible. He concluded, therefore, that if these cells (rest- 
ing-spores) are removed from the fluid and exposed to air, 
they will produce sporangia in the ordinary way ; and this he 
found to be the case. Under these circumstances a vigorous 
germination took place after from one to three days, a small 
sporangiophore and sporangium developing from each cell, 
their sizes varying according to that of the resting-spore which 
produces them, as also does the number of spores found, 
which varied from four to twenty-four. These sporangiophores 
presented in every respect the characters of those of Mucor 
racemosus. Kach sporangium was furnished with a very 
small “columella,” the nearly horizontal septum which 
separated it from the receptacle; the wall of the sporangium 
containing in some cases small deposits of calcium oxalate. 
From every spore proceeded an ordinary mycelium. It would 
appear therefore that the resting-spores of Mucor racemosus 
are portions of the mycelium destined for development into 
receptacles, but which pass into the resting state when air is 
excluded, and in this condition may produce the plant 
under water, but when exposed to air produce the normal 
receptacles. 
Mucor racemosus is the only species that thrives under 
water, and hence the only one, with the exception of the 
nearly allied forms, that produces these peculiar resting-spores. 
In M. Mucedo small pieces of the mycelium were noticed, 
* * Magazine of Zoology and Botany,’ vol. ii, p. 740. 
2 Flora,’ 1857, p. 417. 
VOL. XV.——-NEW SER, L 
