238 



MONOGRAPH OF THE LABOULBENIACE^E. 



tion of accessory perithecia. This abnormal condition has been seen several times in the 

 genus Ceratomyces (Plate XXV, fig. 7), and occurs also in Choatomyces, Corethro- 

 myces, Stigmatomyces, and a few others. In Rhachomyces is found the most frequent 

 and remarkable instance of this nature, the accessory perithecia arising in this in- 

 stance in two distinct ways. In the one case, two 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 

 (Plate XII, 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 plate. 

 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. In the species referred to 

 [P. geminaia, Plate VI, fig. 7), the receptacle usually bears a terminal pair of perithecia. 

 When, however, the individuals have grown under rather unfavorable conditions, as, 

 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 with the others. 



To a similar failure of fertilization is also to be attributed the usually marked increase 

 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 II, 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 the 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 examples well illustrate the fact that the cell 

 series of the perithecium proper are merely eight modified, but independent, filaments 



