416 DR. D. D. CUNNINGHAM ON THE CONIDIAL 
prominences now appears on the dilatations, and each of its members, after growing ` 
outwards for a short distance, in its turn becomes dilated apically, accumulates proto- | 
plasm, and is ultimately converted into one of the capitella previously described. Over | 
the upper hemisphere of each capitellum sterigmata are now developed, and the forma- _ 
tion of conidia follows in due course (fig. 3). The only feature distinguishing the 
capitella of cultivated from those of natural specimens of the plant lies in the fact that 
the lower barren hemispheres of the former do not become so thickened as to form the ` 
distinct funnel-shaped structures so characteristic of the natural specimens subsequent 
to the fall of the conidia. | 
Such are the characters of the conidial fructification developed on a mycelium derived ` — 
.from the conidia of the natural plant cultivated in a medium affording abundant — 
nutritive material. Where, however, a weak medium is employed, or where too many E 
conidia are sown in a strong medium, or where the mycelium continues to produce 
fructification after the nutritive properties of the medium have been exhausted during | 
the course of the cultivation, various abortive forms are developed deviating con- a 
siderably from the normal type. In the natural plant the heads, as previously men 
tioned, frequently produce thirty or even more sterigmatous capitella, and those arising ` 
from a well-nourished mycelium in artificial cultivations may produce as many as | 
fifteen or twenty. In those cases, however, in which nutrition is imperfect, only a small 
number of capitella are produced, and filaments are encountered with numbers dimi 
nishing through various degrees until we find specimens with only two capitella. The 
process of abortion does not, however, reach its climax here; for a further stage occurs in 
which no capitella are produced, and in which the dilated extremity of the filament gives. 
direct origin to the sterigmata (fig. 5). 
Numerous cultivations of conidia obtained in primary auem always gave a like 
result, however strong a nutritive medium was employed. Abundant fructification was | E 
frequently produced; but the heads were invariably of a poor type and the conidia of — 
small size. Only a few capitella were produced in any case, and the proportion of heads ` 
failing to produce capitella at all was very large. Tertiary cultivations of conidia 
obtained from the previous series usually failed entirely to produce fructification. The E 
conidia in many cases germinated, but the mycelium was, as a rule, very feeble and 
soon ceased to grow. Cultivated under the artificial conditions which were employed, - 
the plant appears to undergo a progressive loss of vigour with each generation, leading ` 
to the dying out of the members of the third generation without any provision for 
reproduction. í 
The conidial form of fructifieation was, however, not the only one developed i in these 
cultivations. On the contrary, two other forms, one sporangial the other chlamydo: 
sporous, were obtained. 
The former of these occurs very frequently, and, in fact, under conditions to be pre- 
sently described, it appears almost invariably. That this fructification really belongs to 
the same plant as the zygosporic and conidial forms previously described, there can, 
I believe, be no doubt. The grounds for this belief are as follow :—1. Numerous careful — 
cultivations of limited numbers of conidia have given a mycelium producing such 
