23 4 THAXTER. — MONOGRAPH OF THE LABOULBENIACE.E. 
developed aquatic species of the genus Laboulbenia. It is therefore among the Ceratomycetinese, of 
the accompanying Key, that one would look for suggestions in this connection. That the vegetative 
characters of this series, far from being simple, are quite the reverse, might have no significance in this 
respect; but if one presupposes an origin for the group from aquatic types near the simpler Florideae, it 
is evident that in these water forms, the antheridial characters, which afford by far the most reliable and 
fundamental characters for general groupings in these plants, are more unlike the antheridia of the red 
algffi than those of the more highly developed terrestrial genera. In any attempt to arrive at a conclusion 
concerning these matters, several fundamental questions need answers which are not as yet forthcoming. 
First, has the un specialized antheridial cell of Rhynchophoromyces or Zodiomyces, for example, become the 
specialized cell of the Laboulbeniacese, through conditions which may be suggested by those found in 
Coreomyces; or has the passage been in the reverse direction, resulting as an adaptation more likely to 
insure fertilization under the conditions of aquatic life. The second supposition, indeed, seems by no 
means an unlikely one, and Ceratomyces, which is assumed, at least, to produce its sperm-cells in coherent 
threads, would represent the culmination of this tendency in a modern genus. 
Again it may be asked whether the simple antheridium has been derived from the compound, as 
might be suggested by the conditions seen in Dutichomyces, or by a reduction to one cell of such a com- 
pound antheridium as is found in Rickia: or, as seems more probable, has the reverse process actually 
occurred. Furthermore it is by no means evident whether the unisexual, or the hermaphrodite condition, 
which arc associated with both the simple and compound type of antheridium, is primitive or the reverse. 
Although the general tendency in upward series appears to be toward a separation of the sperm- and 
egg- -ell-function on different individuals, and this condition has no exceptions in the highest plants, by 
far the most highly developed and apparently modern genera of Laboulbeniales are hermaphrodite: 
but if we look for what is absolutely the simplest condition found in this group, we find it without question 
in the genus Amorphomyces, a unisexual type with simple antheridia. And here it may be pointed out 
that all the forms which grow on Blattid*, supposed by entomologists to be among the most ancient types 
of insects, are unisexual, with simple antheridia. 
The not uncommon phenomenon already mentioned above, and formerly illustrated in Laboulbenia 
inflata, Monograph, Plate III, fig. 5, which involves the atrophy of one member of the usual spore- 
pair, may be perhaps significant in this connection; in that it suggests the survival of a tendency to form 
two kinds of individuals, one of which had become superfluous after the appearance of antheridia on the 
female individual. This is still more strikingly suggested by instances such as the one illustrated here- 
with, on Plate XLIX, figs. 16-17, which, although rare in general, are common in this and a few other 
species. Here one member of the spore-pair, becomes not only a dwarf individual, but is absolutely 
Uiusexual, bearing a well developed and normally functional antheridial appendage. Yet here also, 
the monopolization of food supply by one member of the spore-pair, may have led to a dwarf habit and 
partial loss of function in the other, and it is not by any means inconceivable that, through gradual loss 
o its male function by the vegetatively vigorous individual, a unisexual condition might become a fixed 
phenomenon, m both members. 
Since the series may thus be read upward or downward as one prefers, and Amorphomyces is quite 
» ike y to ,1 ustrate a last step in retrogression as a first in evolution, one may be pardoned, if like the 
nter he coni sses his complete agnosticism in these matters, an agnosticism which embraces the question 
