222 THAXTER. — MONOGRAPH OF THE LABOULBENIACE^. 
l>e apparent between the male and female spores in dioecious genera. It may be here remarked that 
the cytological phenomena in this connection, which lead up to the sexual differentiation and pairing 
in the ascus of these male and female spores, is likely to prove of unusual interest. 
Moschomi/crx and Compsomyces remain the only genera in which the presence of octosporic asci 
has been definitely determined. The writer has been unable to satisfy himself, however, that this is not 
also the condition in Herpomycrs. If this were actually the case, it would involve the curious phenom- 
enon of absolute sex differentiation in the last mitosis, which would not necessarily occur in a four spored 
1ISCUS. 
In almost all the species the first step in germination consists, after the spore has become attached, 
or even before, in the formation of the familiar hoof-like organ of attachment and absorption, the foot: 
an indurated, firmly attached, blackened rim, surrounding a thin membrane which is in direct contact 
with the surface of the host and through which materials are absorbed into its cavity, the latter being, as 
a rule, in direct communication with that of the basal cell of the receptacle; although, in some instances 
at least, it is evidently separated by a septum, Plate XLIX, fig. 16. 
The nature of this foot may be somewhat variable. In Corcomyces, for example, it may be modi- 
fied to form a spreading, almost rhizoidal structure, Plate LXXI, fig. 14, of characteristic appearance 
somewhat similar to that of Zodiomyces, The most striking departure from the normal type, however, 
is seen in a relatively small number of species, and was illustrated in the writer's earlier Monograph (Mos- 
chomyrc,- and Ithizomyces). In these instances the parasite obtains its nourishment directly from the 
body-cavity of the host by means of a penetrating intrusion. Such intrusions a re usually associated with 
growth on a thin or soft integument. Thus Moschomyccs, in which the penetrating organ expands to 
form a cellular cushion, grows on the thin integument beneath the elytra, or at the bases of the legs of 
its othenv.se hard-shelled host. But the most striking instances of this nature are seen in forms which 
live on soft bodied Diptera, and produce a more or less well developed filamentous rhizoidal apparatus. 
In Dnncromycr* rhizophorus the thin skin on the under surface of the abdomen of a small fly is perforated, 
as is shown in Plate XXVIII, figs. 6-8, and a stout tapering filament extends some distance into the 
senu-fluid contents of the abdomen, furcate in the female, and simple in the male individual. A beauti- 
fully developed branching rhizoid is seen in Ceraiomyces Dahlii, Plate XLIII, fig. 4, and a still more 
copiously branched organ of this nature is present in the species of Arthrorhynekus, the copious and 
intricate branching of which is merely suggested in Plate XLVIII, fig. 2. 
It is a remarkable fact that the presence or absence of such penetrating organs is not necessarily an 
at nlnue of all the species of a given genus, or even of those which grow on the same, or similar hosts. 
1 ins (;erai/Ym*w .Q„Z^ in?- . _ ° ' 
'atomy ce 
i all the other 
r„Tl I v"? rhiz ° phorous - *>*—»«■ rHzo,,, m , ,„„ r ,„v, r , is the only specie, in n 
con , Me gcnus , ,„,,, has tI]is character; a]thoug|| fc ^^ i|||ir 
r, ::"":' °tz i ". ,he ■— p,,sition - • ***» ** ^ *«■ & *• «z «*«*. 
In 1 v 2 " 0r IT y. H " ; ' e " ! ' ° n " ,e ddirate ""'»«'"""' » f «*^ bodied Tenaites, 
Z X 7- T T al foot figurcd - tmm w ~. ta P ^ '«■ ■» '■ - *■ *>«- M — 
genus Ucrpomyces 
* 
penetrate 
