146 DIVISION IL—-COURSE‘ OF DEVELOPMENT OF FUNGI. 
zygospores, these organs have never yet been observed ; and since some of the species 
have been frequently and carefully examined, it may perhaps be conjectured that they 
do not at present produce zygospores, but only gonidia. 
The members of the group of Mucorini, with the exception of the doubtful 
genus Zygochytrium, which will be considered in a later page, are plants of the dry 
land, and grow most of them on dead organic bodies (especially animal excrements), 
some being parasitic on other Mucorini. 
A spore gives rise to a mycelium having the form of a much-branched unicellular 
tube, as may be seen most readily by cultivating the plant in drops of fluid or in 
mucilage on a microscopic 
slide (Fig. 71 2), and it 
is not until gonidiophores 
begin to be produced that 
the tube is in a condition to 
form the transverse septa 
which then usually appear in 
it. The Zypical gonidiophores 
(Fig. 71 g) begin after one 
or more days’ time to shoot 
upwards from the mycelium 
which has spread in the 
substratum; they appear in 
the form of branches which 
are usually erect, and, like 
the parent-tube, are at first 
without transverse septa. In 
some species, as Mortierella 
and Syncephalis, they are al- 
most microscopically small ; 
in most cases, however, they 
are of considerable size,from 
one to several centimetres 
in length, in Phycomyces 
10-30 cm. Older or im- 
perfectly nourished mycelia 
may subsequently produce 
a fresh crop of accessory 
Nae 
= 
N 
I 

FIG 71. B. Phycomyces nitens. Plants three days old grown from a gonidium in rel . 
gelatine with decoction of plums; the mycelium 2 has spread horizontally, g a gonidio- gonidial Sor MS. But in all 
‘phore. A,C, D Mucor Mucedo highly magnified. 4 sporangium in optical longitu- = . 
dinal section. In C the germinating zygospore z is borne on suspensors; K germ-tube, SPECIES which have been 
it D j i bb slightly, 4, C and D more = 
thoroughly examined the 
mycelium under favourable 
circumstances completes its development by forming zygospores. Finally the 
ripe zygospore, after remaining dormant for several months, puts out one or 
more strong germ-tubes, which develope at once without mycelial formation 
into the typical gonidiophores which are characteristic of the species (Fig. 71 C). 
The gonidia of every species invariably produce, if the conditions are suitable, a 

& 5 aa g P 
highly magnified. After Brefeld from Sachs’ Lehrbuch. 
