~ \ Matte Rr ida’ Sy eae ' Ve Ge ee - 
“. Pata oa 3 Pe, ve 
J * i . A My Wie Pent ty we bi 
‘ P a mem “ ov Oe Ee AW ey, Ue ete 
i : ; Meh “tT aera ea yi 
. 4 ~ p; 
280.0 Structural and Physiological Botany. 
he mycelium, while others direct themselves upwards, and 
constitute the aerial hyphze, which break up into conidia. 
In AZucor the spores, instead of being naked exposed 
cells, are produced within special bodies known as sforangia 
or asci, roundish heads borne at the extremity of filaments 
which rise vertically into the air from the hyphe. ‘The wall 
of the sporangium is rough from minute particles of calcium 
oxalate. ‘The sporangium is easily ruptured, dispersing the 
spores; the greater part of its wall then disappears, but a 
small collar frequently adheres to the filament. The cavity 
of the filament does not communicate with that of the 
sporangium, but is separated from it by a partition which ~ 
bulges into the cavity of the sporangium, forming a central 
pular or projection. and termed the columella. The germina- 
tion of the spores resembles in all essential points that of 
Penicillium, the organism remaining for a time truly uni- 
cellular. The sforangiophores, or filaments which bear the 
sporangia, are given off vertically ; the free end dilates into 
a rounded head which developes into the sporangium, and is 
separated by a septum which constitutes the columella. 
The protoplasm in the sporangium becomes gradually sepa- 
rated into a number of masses by free cell-formation, each of 
which excretes a cellulose coat, and becomes an ascospore. 
Mucor 1s also propagated sexually by conjugation, z.e by 
the production of zygospores in the manner already described 
(p. 271). The cell-wall of the zygospore becomes separated 
into two layers, an outer one of a darker hue, the exosfore, 
and an inner colourless layer, the evdospore. ‘The germina- 
tion of the zygospore, which takes place only after a period 
of rest, resembles that of an ordinary spore.—ED. | 
The classification of Fungi is still in process of continual change 
and improvement. The foliowing is that adopted by De Bary :— 
I. PHYCOMYCETES., 
a, Saprolegniee. b. LPeronosporee. c. Mucorini. 
The vegetative part of the Fungus which does not subserve the pro- 
cess of reproduction consists, in many forms altogether, in others at 
