368 



MONOGRAPH OF TEE LABOULBENIACE^E. 



MOSCHOMYCES Thaxter. Plate XT, figs. 16-18 and 26. 



Proc. Am. Acad. Arts and Sci. Vol. XXIX, p. 97. 



Receptacle composed of a sucker-like compacted mass of parenchymatous cells penetrating 

 the softer chitin of the host and giving rise above to numerous free cells from the distal ends 

 of which are produced solitary stalked perithecia and appendages. Perithecium very large, 

 sub-conical, pointed, the apex symmetrical, borne on two simple superposed stalk-cells followed 

 by three small basal cells ; the basal stalk-cell bearing from its distal end a single simple sterile 

 appendage. Appendages septate, sparingly branched or simple, the fertile ones stouter, bearing 

 the antheridia on short branchlets. Asci sub-cylindrical, eight-spored, arising in great numbers 

 and in many rows from a single ascogenic cell. Spores minute, once-septate. 



This genus, although at first sight so remarkably distinguished from all others by its habit 

 of penetrating its host and by a cellular base, may yet prove merely a well-marked species of 

 the preceding genus. This suggestion is made on the supposition that an " individual " such 

 as is represented by fig. 16 is in reality an aggregation of as many individuals as there are cells 

 in its penetrating base. The spores are discharged in enormous numbers from the perithecium, 

 and show a marked tendency to adhere in masses (fig. 18). It is a question, therefore, 

 whether the " individual " as figured does not represent the product of one of these masses and 

 not the product of a single spore. Apart from this apparently compound habit, the essential 

 characters of the genus are very similar to those of Compsomyces. If this supposition is 

 correct, the sucker-like base is morphologically a compound foot, while the " numerous free 

 cells " above described as rising from it represent the sub-basal cells of the true receptacle. 

 Whether the latter has a basal cell distinct from the intruded cells cannot be seen in the speci- 

 mens examined. 



The antheridia are flask-shaped cells borne at the tips of short branches, which arise 

 near the ends of the stouter appendages (fig. 26), and are unlike those of Compsomyces. 

 In one specimen, unfortunately destroyed, several trichogynes were observed, which though not 

 as luxuriant as is often the case in Compsomyces, were terminated by the same regularly coiled 

 spiral branchlets. As far as can be determined, the asci arise from a single ascogenic centre, 

 apparently a single large cell, but possibly a coherent group of cells. The asci (fig. 17) are sub- 

 cylindrical, with a long, slender pedicel (partly broken in the figure), eight-spored and produced 

 in very great numbers. The ascus mass is a most remarkable object, when viewed in fresh 

 material under the microscope. What may be called the dorsal view of this mass (represented 

 in the second perithecium from the right in fig. 16) shows with great distinctness the round ends 

 of a multitude of asci with their contained spores, projecting towards the observer and gradually 

 losing themselves above in the mass of spores, which must be counted in a single perithecium 

 almost by thousands. The structure of the perithecium is, like that of Compsomyces, unusual, 

 there being five transverse series of wall-cells, the lower four marked by singular ridges. 



