238 MONOGEAPn OF THE LABOULBENIACE^. 
tioii of accessory peritliecia. This abnormal condition has been seen several times in the 
genus Ceratonijces (Plate XXV, fig. 7), and occurs also in Chcetomyces, Corethro- 
injces, Stigmatomyces, and a few others. In Rhachomyces is found the most frequent 
and remarkable instance t)f this nature, the accessory peritliecia arising in this in- 
stance in two distinct ways. In the one case, t\vo may occur side by side as is repre- 
sented in Plate X, fig. 22, or, through the proliferation of the receptacle below the 
base of the perithecium first formed, a second may arise a short distance above it 
(Phite XIT, fig. 2). The same process may even be repeated, so that two or even 
three accessory perithecia may succeed one another, as in fig. 14 of the same 
In the last mentioned cases the proliferation, usually, if not invariably, follows the 
abortion of the perithecia first formed, the trichogynes of which have, for some reason, 
failed to become fertilized. 
One further instance of the abnormal occurrence of perithecia may be mentioned 
which has several times been noticed in the genus Peyritschiella. In all but one of 
the known species of this genus, the receptacle is terminated by a single perithecium 
(Plate VI) which may exceptionally be replaced by two. lu the species"- referred to 
(P.^emma^«,Plate VI,fig. 7),the receptacle usually bears a terminal pair of perithecia. 
When, however, the individuals have ij-rowm 
favorable cond 
for instance, near the extremities of the anterior pair of legs of their host, the lower 
transverse cell rows of the receptacle may give rise externally to several additional 
perithecia, which develop normally witli the others. 
To a similar failure of fertilization is also to be attributed the usually marked increasb 
in the production of antheridia in such cases, which has been previously noted. Such 
antheridia are, as a rule, formed normally on the appendages; but in certain instances, 
on the other hand, this increase is effected by an abormal process, as a result of which, 
accessory antheridial branches take the place of the perithecium, growing from the 
cells at its base (Plate 11, fig. 8). In some cases the branches produced under these 
circumstances may grow up through and within the atrophied perithecium, emerging 
between its terminal cells, as is represented in Plate II, fig. 9. A condition similar to 
this IS figured by Peyritsch (1873, Plate II, fig. 11), the protruding filament having 
been mistaken by him for a trichogyne. A specimen in which a similar growth from 
within the base of the perithecium has resulted in tlie production of large numbers 
of branches is represented in Plate II, fig. 10. In this instance the abnormal growth 
had apparently followed an injury, by which the upper half of a normally matured 
perithecium had been destroyed. Such exampl 
the f 
of the perithecium proper are merely eight modified, but independent, fil 
■si, 
