CHAPTER V. COMPARATIVE REVIEW. ASCOMYCETES. ASCOBOLUS. 



a series of simple apparently similar cells rich in protoplasm which grow to be about 

 as long as broad, and then a preliminary cessation of this growth takes place. Slender 

 branches which spring from the mycelium near the archicarp, and also branch 

 themselves, now grow in the direction of the archicarp and apply themselves and 

 their branches closely to its free extremity (Fig. 95 /). They behave in this respect 

 like the antheridial branches of Eurotium and Erysiphe and may therefore receive the 

 same name. Their contact with the archicarp is followed at once by the formation 

 of a large number of fresh branches on the hyphae which produced them and on 

 adjacent mycelial hyphae, and all these later branches grow closely interlaced round 

 the archicarp and the first antheridial branches, which from this time cease to be 

 distinguishable. The archicarp is thus at once inclosed in a compact hyphal coil, 

 the envelope, which then grows considerably, partly by the introduction of new hyphal 

 branches partly by the increase in size of those previously formed, the cells of which 

 become vesicular and for the most part 

 continue united together into a dense 

 pseudo-parenchyma. A few peripheral layers ' 

 of these cells form a thick-walled rind, 

 which is yellow in Ascobolus furfuraceus 

 from the colour of the membranes but is 

 differently coloured in other species, and 

 which sends rhizoid-hyphae into the sub- 

 stratum at the points of contact, while in 

 many species, but not in A. furfuraceus, it 

 produces spreading hairs of peculiar form 

 and arrangement. With all these changes 

 the sporocarp assumes a spherical shape, 

 and the course and direction of its growth 

 are such that the archicarp remains in- 

 closed in the basal portion of the sphere 

 where it rests on the substratum. The 

 formation of paraphyses begins at the same 

 time as the differentiation of the rind in 

 the opposite apical region, and their first 



beginnings appear as branches from a zone of narrow cells still rich in protoplasm 

 in the tissue of the envelope, the subhymenial zone, which passes across the apical 

 region beneath the rind. The paraphyses are formed as slender hyphal out-growths 

 in this region ; each of them can send out new and similar branches of more than 

 one order near its point of origin. But the ends of the branches of every order grow 

 into slender long-celled filaments which constitute the paraphyses, and converging at 

 first have all a direction from the subhymenial zone towards the apical region of the 

 rind and end below it. In proportion as they elongate and increase in number 

 by the introduction of new branches from the subhymenial region and whilst the 

 surrounding parts follow these processes of growth, the space between the rind and 

 the subhymenial layer grows broader, but is always being filled up by the paraphyses 

 which are arranged close beside one another as the first commencement of the hymenium. 

 It may be observed here by anticipation that the growth of the hymenium continues 



FIG. 95. Ascobolus furfuraceus. Median longitudinal 

 section of a young fructification ; m mycelium, c archicarp, 

 with the ascogenous hyphae s spreading in the sub-hymenial 

 layer and the asci a dark, / antheridial branch, f r tissue 

 of the envelope from which the paraphyses h spring. Dia- 

 grammatically represented by Sachs after Janczewski. 



