a Fungus causing a Disease of the Sugar-cane . 527 
Microconidia. 
This form of reproduction is a modification of the one last 
described, developing from the same hyphae, and owing its 
structural peculiarities to exposure to light and air during 
growth ; thus illustrating from an unexpected quarter, a 
general rule amongst groups of Fungi showing a transition 
from a subterranean to an aerial condition. The various 
stages are clearly developed in sequence in the Gastromycetes, 
where, from the subterranean Hymenogastreae with an un- 
differentiated indehiscent peridium, very large spores, and 
without any arrangement for spore-diffusion, we pass to the 
above-ground Lycoperdeae with a differentiated peridium, 
capillitium, and small spores, the modifications being for the 
purpose of facilitating spore-dispersion by wind ; and finally 
in the Phalloideae we find the mature sporophore elevated 
into the air at the top of a long stem-like receptacle, usually 
furnished with bright colours and a penetrating odour, for 
the purpose of attracting insects by whose agency the very 
minute spores are dispersed. 
In the present instance, the advance made in the general 
structure of the microconidia over the macroconidia tends 
in the direction of favouring the dispersion of the conidi a 
by wind ; the entire fructification is developed in the air, the 
conidiophores are elongated, and the conidia are comparatively 
minute (Fig. 7, c, d.) 
Preceding the formation of microconidia, the hyphae in the 
tissues concentrate at those points where the surface of the 
cane has been recently wounded and form a dense weft ; the 
hyphae becoming thinner as they approach the surface. From 
this weft the aerial conidiophores originate in immense num- 
bers, forming a velvety pile on the surface of the wounded 
portion. The conidiophores when mature are of a pale grey 
colour, sparingly septate, and vary from 150-220 fx in length, 
become swollen to a breadth of 12-16 /u at a short distance 
from the base, and gradually taper to the apex where they 
are about 6 ju in diameter. The conidia are developed in 
