228 



THAXTER. — MONOGRAPH OF THE LABOULBENIACEjE. 



which the appendage is remarkably developed, yet the host is a fly which may be assumed to spend most 

 of its life, at least, in the free air, although it is said to be riparian. 



Male Sexual Organs. A general division of the Laboulbeniales was formerly made by the writer 

 on a basis of the differences which appeared to exist in the method of abj unction of the sperm-cells; those 

 in which the latter were endogenously formed, being discharged free from a specialized antheridial cell, 

 "Endogeme", and those in which they appeared to be exogenous branchlets, or segments of branchlets, 

 separated from the appendages, "Exogeme". It appears somewhat doubtful, however, Whether this 

 distinction can be as clearly drawn as was at first supposed, in view, particularly, of the conditions seen 

 in Coredmyces, a genus very remarkable in its structure and development. The antheridial cells in this 

 instance, are merely undifferentiated cells of secondary appendages arising as branches from special 

 cells of the receptacle lying below the origin of the procarp, and not corresponding to any portion of the 

 primary appendage, which is wholly obliterated during the development of the perithecium. As in 

 Rliynchophoromyccs rostratus, (Monograph, Plate XXIV, figs. 21-24), the antheridial cells are in- 

 tercalary as well as undifferentiated; but in the present instance develop a short cylindrical neck through 

 which free sperm-cells are discharged very much as in the endogenous forms. That there is a gradual 

 transition, rather than a sharply defined line of demarcation between these two general types, is further 

 suggested by the conditions seen in Hydrophilomyces, the species of which were formerly included in 

 Ccratomyccs. If the structures represented on Plate LXVIII, figs. 3-4, are in reality antheridia, we have 

 here a type that, although in many respects it corresponds closely to that of the Ceratomyces-group 

 which is likewise aquatic, discharges its sperm-cells free, from cells which are almost as distinctly spe- 

 cialized as are those, for example, of Compsomyccs or of Ecteinomyces, Plates XLIII, fig. 12 and LI, fig. 

 18. The antheridia of Kainomyccs and Euzodiomyccs, genera the near relationship of which to Zodi- 

 omyces may be assumed, are as yet unknown, owing to the imperfect character of the material available. 

 Neither is the nature of the male elements absolutely determined in Ceratomyces, or in Autoicomyces, in 

 both of which they appear, however, to be segments of certain slender branchlets. The conditions exist- 

 ing in the genus Misgomyccs also, which may be related to these forms, are still unknown; so that, as far 

 as any definite production of exogenous male elements is concerned, it must be confessed that it is defi- 

 nitely known only in Rliynchophoromyccs and Zodiomyccs. Until the exact conditions can be determined 

 in the cases above referred to, this general distinction must remain of doubtful value, and in attempt- 

 ing to construct a key which should at the same time indicate in a general way the relationships of the 

 genera, the main divisions have been based on the differentiated or undifferentiated character of the antheri- 

 dial cells, a distinction which, however, can be considered by no means absolute, since it might exclude 

 from the latter class Hydrophilomyces, a genus, as above suggested, apparently most nearly related to the 

 Ccratom yces-gvowp. 



A further general distinction was made in the group of so-called Endogenae, based on the compound 

 or simple nature of the antheridia: the simple type consisting of cells indeterminately placed, or more 

 or less definitely associated, free, or at least with free and independent efferent tubes; the compound 

 type involving not only the definite association of several or many antheridial cells in a determinate group, 

 specific in its character, but also a different method of discharge; the efferent tubes of all the antheridial 

 cells composing such an antheridium, opening into a common cavity, whence the sperm-cells make their 

 exit through a single opening or passage. Although this distinction appears to be almost absolute, and 



