FRUCTIFICATION OF CHOANEPHORA. 417 
sporangia. 2. The cultivation of spores from a sporangium has resulted in the develop- 
ment of a mycelium bearing the conidial form of fructification. 3. Sporangial filaments 
have been traced to the same mycelial tubes as conidiiferous ones. 4. The conditions 
securing the development of sporangial filaments on a mycelium produced from conidia 
have been in a great degree determined. 5. Specimens of Zibiscus-decoction when 
exposed to the air, although they become the site of the development of various moulds, 
do not show any forms producing such sporangia save when the conidia of Choanephora 
have been introduced into them. 
The first thing to be noted in reference to the sporangial fructification is, that it does 
not appear to occur on the plant in its natural state. The conditions under which it 
occurs are those in which the poorer types of conidial fructification are produced. It 
occurs along with these:—1. On mycelia growing on an exhausted medium; 2. On 
mycelia developed from the conidia produced in artificial cultivations. The sporangial 
fructification has never been obtained apart from the conidial form ; but the proportions 
of the two forms on the same mycelium varies greatly in different instances. As a rule, 
however, the conidial heads on any mycelium considerably exceed the sporangial ones in 
number. Any cultivation in which conidial heads with very few or no capitella abound 
may be expected to produce sporangia. The two forms of fructification occur simul- 
taneously ; but in those cases where sporangia are produced on a mycelium derived from 
the natural plant, cultivated in a medium which was originally rich enough to secure 
the formation of well-developed conidial heads, the sporangia do not occur simultaneously 
with such heads, but along with the poorer types so frequently produced by those 
portions of mycelium which continue to grow and produce fructification on the partially 
exhausted medium. 
The sporangial filaments do not, asa rule, attain a length equalling that of the conidial 
ones with which they are associated, and are frequently somewhat curved at the apex. 
The superior extremity of each filament dilates into a small rounded sporangium, which, 
from the presence of numerous calcareous particles, is conspicuously tuberculated 
(figs. 9 & 10). The sporangia are separated from the filaments by a transverse par- 
tition, which is sometimes flat, at others arched upwards into a small prominent colu- 
mella (fig. 10). They vary somewhat in size, but, on an average, measure about 0:027 
millim. in diameter. When first formed they are pale yellow, but as the spores mature 
they assume a fine deep Vandyke-brown colour. This colour is, in any case, due to that 
of the contained protoplasm or spores; for on the evacuation of these the sporangial 
membrane is seen to be colourless. The sporangia at first present an even rounded 
outline; but as the spores enlarge and approach maturity, they come to fill the cavity 
completely, and pressing upon the walls of the sporangium stretch them tightly, and 
cause them to assume a nodulated contour, corresponding with that of the contained 
mass of spores (fig. 9). When mature the sporangia rupture irregularly, the line of 
fracture being in general more or less vertical; and subsequently they disintegrate and 
disappear, leaving the spores free. The number of spores produced within any spo- 
rangium is very limited, seven or eight being a common number, akhough in rare 
instances there may be various numbers up to seventeen or eighteen. The spores vary 
