SECT. I 



CRYPTOGAMS 401 



Order 8. Laboulbeniaceae (*^) 



The Laboulbeniaceae are a group of minute Fungi occupying an isolated 

 position ; our knowledge of them is largely due to the work of Th.vxtick. Their 

 thalhis consists of two to a number of cells, and is attached to the body of the 

 insect, most commonly a beetle, on which it is parasitic by means of a pointed 

 process of the lowest cell inserted into the chitinous integument of the insect 

 or by means of rhizoids which penetrate more deeply. Sticjmatomyces Baeri 

 which occurs on house-flies in Europe may be taken as an example. The bicellular 

 spore (Fig. 332, A), which has a mucilaginous outer coat, becomes attached by its 

 lower end (5), and divisions occur in both cells (C). From the upper cell an appendage 

 is developed bearing a number of unicellular, flask-shaped antheridia {D, an) from 

 wliich naked spherical spermatia without cilia are shed. The lower cell divides 

 into four {D, a, b, c, d), and the cell a projects and gives rise to the multicellular 

 female organ. The true egg-cell [E, ac), which is called the carpogonium, is 

 suri'ounded by a layer of cells. Above the carpogonium come two cells {E, tp, t) 

 the upper of which is the freely projecting trichogyne or receptive organ for the 

 spermatia. The behaviour of the nuclei has not yet been followed, but probably 

 a fusion of male and female nuclei takes place in the carpogonium. The latter 

 becomes divided into three cells, of which the uppermost disappears, the lowest 

 {F, st) remains sterile, while from the middle cell the asci grow out. Each ascus {G) 

 produces four spindle-shaped, bicellular spores. The similarity of the sexual 

 organs to those of tlie Florideae and of the lichen-forming Ascomycetes is of great 

 interest. 



Sub-Class II. — Basidiomyeetes (-'■'' ^^' ^-' ^^' ^^) 



The Basidiomyeetes no longer possess sexual organs ; only in 

 the Uredineae or Rust-fungi are structures found which can be 

 regarded as persisting though functionless male organs, and cells 

 which appear to correspond to the carpogonia of Ascomycetes. In 

 place of asci, basidia are present which produce by a process of 

 budding in most cases four basidiospores. The basidia agree with the 

 asci in containing when young two nuclei, which fuse with one 

 another. The reduction division appears to follow on this nuclear 

 fusion or karyogamy. The resulting nucleus undergoes two 

 divisions, and the four resulting nuclei pass into the spores which 

 are budding off (I'ig. 333) {^^). A mycelium with uninucleate cells 

 develops from the spore. 



The basidia present three distinct types. In the orders Uredineae 

 and Auricularieae the upper portion of the basidium is divided by 

 transverse walls into four cells ; each cell bears on a thin stalk 

 (sterigma), arising near the upper end, a single spore (Fig. 334, A). 

 In the Tremellineae, on the other hand, the basidium is divided by 

 longitudinal walls into four cells, each of which continues into a 

 long tubular sterigma (Fig. 334, B). The basidium in the Hymeno- 

 mycetes and Gasteromycetes is unicellular, and bears as a rule four 



2d 



