FRUCTIFICATION OF CHOANEPHORA. 415 
tinct rupture of the exospore occurs, the line of fracture being distinctly evident against 
the budding-tube (figs. 7,8). As the latter increases in age, and as its walls become 
distinctly differentiated from its contents in the form of a definite membrane, this line of 
demarcation is gradually obscured, and finally disappears, the two membranes apparently 
being fused together. | 
The germinal tubes generally arise from the sides of the conidia, so that the axis of 
growth of the new plant is at right angles to that of the parent; occasionally, however, 
the tubes are emitted from one or other extremity (fig. 7). They are thick, and are 
usually undivided for some distance; but in some cases, as they escape from the conidia, 
they form a more or less marked dilatation, from which two filaments of equal size arise. 
The streaming of the protoplasm is very active in the young filaments, and, as the latter ` 
grow, more and more of the contents of the conidia pass into them. As the process 
continues, the conidia are gradually emptied, for some time, however, retaining a narrow 
peripheral layer of protoplasm, and ultimately being left as brown sacs full of watery 
fluid (fig. 8). The filaments continue to grow and ramify rapidly; and from the main 
system of tubes thus produced short lateral filaments are developed. These give off 
several branches, and, soon becoming emptied of their protoplasmic contents, are shut off 
at their origins by transverse septa. The main tubes are at first entirely devoid of 
septa; but, as they increase in length, the protoplasm advances within them, so as to 
leave large tracts occupied by watery fluid only; and in such tracts septa are occa- 
sionally formed. | 
After the mycelium has continued to grow for some time, fructification, in the form of 
aerial conidiiferous filaments, begins to be produced. The filaments, in the artificial 
cultivations, may be traced directly to the parent tubes, no intermediate dilatations, such 
as occur in the natural plant, being formed. Where the conditions of nutrition are very 
highly provided, the formation of reproductive bodies is delayed, and the mycelium con- 
tinues to grow luxuriantly for a considerable time. Under fair nutritive conditions— - 
where the decoction is a strong one—a crop of fructification is usually produced within 
twenty-four hours from the commencement of the cultivation ; but this is more or less 
determined by the time of day at which the sowing of the conidia is effected, as it is only 
during the hours of darkness that the aerial filaments are produced. Supposing the 
sowing to have taken place at 10 a.m., the germinal tubes will generally have been 
emitted within an hour; and by sunset an abundant mycelium will have been developed. 
On the following morning at dawn (say at 5 a.m.) a crop of young conidial heads will be 
present; and this will mature during the course of the next few hours. The rapidity 
with which the conidia are formed and matured is very remarkable, and is rendered very 
manifest by the great change in colour which the heads undergo during ripening. 
The conidial heads, when the plant is well nourished, are precisely similar to those of 
the uncultivated specimens; but the capitella are generally fewer in number, and the 
conidia of comparatively smaller size than in the latter. Every step in the development 
of the heads can here be accurately followed, and the nature of the process is seen to 
be as follows :—The aerial filaments swell out at the apex, and the protoplasm, which is ` 
.— niin ually streaming into them, accumulates in the dilated extremities. A series of 
