LABOULBENIALES 375 



H. Periplanetae the basal cells of the primary and secondary receptacles 

 develop fine rhizoids which penetrate the host wherever they are in 

 contact with it. 



In Stigmatomyces, the appendages are only slightly developed (Fig. 

 248, cell b) and may grow from either the cells of the ascospore or their 

 derivatives; those from the upper cell of the ascospore are called primary 

 appendages, all others secondary appendages. They attain their greatest 

 development in some species of Rhachomyces where they seem to surround 

 the whole plant (Fig. 249, 1) and occasionally project above the peri- 

 thecium. They probably serve for protection and the holding of 

 condensed water. 



In most genera the antheridia are localized in a definite manner in 

 certain positions on the appendage, e.g., at the base, somewhat as in 

 Rhizomyces crispatus (Fig. 250, 2). These simple antheridia may stand 

 in a definite order, as in vertical rows in Stigmatomyces, three vertical 

 rows in Idiomyces, four in Arthrorhynchus, or they may be entirely irregu- 

 larly arranged and (as in certain cases where the perithecium fails to 

 develop) may subsequently multiply in number (Fig. 250, 3). In still 

 other species, as Laboulbenia Gyrinidarum and L. chaetophora, no sper- 

 matia have been observed. 



The Laboulbeniaceae show some variations in perithecial development. 

 The direction of the rows of wall cells may twist in age (Fig. 249, 2), or the 

 perithecial tip may bear appendages known as trigger organs (Fig. 250, 

 1 ) or the number of wall cells in a row may exceed four (in Moschomyces 

 and Compsomyces five, in other genera entirely variable). 



The archicarps of the Laboulbeniaceae have very uniform relation- 

 ships. In all forms studied, the division into the trichogyne, trichophoric 

 cell and carpogenic cell has been observed. Often the trichogyne attains 

 a higher development than in Stigmatomyces. Thus in Amorphomyces, 

 it is still unicellular, but definitely lobed (Fig. 245, 1). In most other 

 genera it is multicellular, at times much branched, either straight, more or 

 less as in Laboulbenia Gyrinidarum (Fig. 252, 1) or helical, as in Comp- 

 somyces verticillatus. How fertilization and nuclear migration occurs in 

 these tufted trichogynes, is still unknown. In some of these forms with 

 complicated trichogynes, as L. Gyrinidarum, spermatia have not been 

 seen and the asci perhaps may develop parthenogamously as in Poly stigma 

 rubrum and various species of Pezizales. 



These relationships were cytologically studied in two very closely 

 related species, Laboulbenia Gyrinidarum and L. chaetophora (Faull, 1912) 

 on the elytra of Gyrinus sp. Fig. 252, 1 shows the archicarp mature for 

 fertilization; it suggests Stigmatomyces Baeri (Fig, 248, 5) and consists 

 of carpogenic cell, trichophoric cell and trichogyne. All of these cells in 

 the Laboulbeniales are uninucleate. The nuclei of the carpogenic cell 

 and the trichophoric cell (Fig. 252, 2) each divides. The septum is dis- 



