342 COMPARATIVE MORPHOLOGY OF FUNGI 



parthenogamous scheme. In Ascobolns glaber, the "transition of the 

 ascogonium to the main hypha is very gradual. Perhaps this degenera- 

 tion in morphological differentiation is related to the degeneration of 

 function. Conversely, the archicarp coils more than in A. citrinus, so 

 that it forms a helix of two or three turns; when mature it consists of a 

 two- to three-celled stipe, a two- to three-celled ascogonium, and at most 

 a three- to four-celled trichogyne. In Ascophanus carneus, it is more 

 strongly developed and consists of a three- to twelve-celled stipe, a three- 

 to seven-celled ascogonium and a three- to five-celled trichogyne. Occa- 

 sionally the latter is absent. Differing from A. citrinus, the nuclei do 

 not migrate toward a single central cell, but the pairing is divided between 

 two to three cells which usually lie near the top; consequently ascog- 

 enous hyphae develop from more than one ascogonial cell. 



Similar differences in the number of privileged sexual cells appear in 

 a third autogamous group. In Ascophanus ochraceus, Saccobolus 

 violascens (Dangeard, 1907), Thelebolus stercoreus (Ramlow, 1906, 1915) 

 and Lasiobolus pulcherrimus (Delitsch, 1926), the nuclear pairing takes 

 place {mutatis mutandis) as in Ascobolus citrinus, in only one cell of the 

 ascogonium; in others e.g., Rhyparobius (Thecoteus) Pelletieri (Barker, 

 1904; Overton, 1906), as in Ascophanus carneus, several of them are shared 

 in the formation of ascogenous hyphae. 



In the form of its archicarp Ascophanus ochraceus connects directly to 

 Pyronema confluens. On a single hypha (or on a few of them), there arises 

 a small group of up to 15 stipitate, swollen unicellular ascogonia, each of 

 which is provided with an occasionally branched trichogyne. Antheridia 

 are no longer formed, the female nuclei pair, as occasionally in Pyronema 

 confluens, within one ascogonial cell and migrate into the ascogenous 

 hyphae. 



Saccobolus violascens and Rhyparobius Pelletieri represent the type of 

 multicellular ascogonium which we have come to know as the rule in the 

 Ascobolaceae. In the former, however, nuclear pairing takes place in a 

 single cell which alone functions as a mother cell of the ascogenous 

 hyphae. In the latter, pairing may occur in any cell of the ascogonium, 

 and the ascogenous hyphae develop from several cells of the ascogonium. 



Thelobolus stercoreus, finally, forms an isolated, peculiarly reduced 

 type which at present cannot be satisfactorily interpreted. The myce- 

 lium consists of uninucleate cells; out of one of these grows the ascogonium 

 in a thick uninucleate branch. Later it becomes bi- to quadri- to octo- 

 nucleate and then separates into several uni- and one binucleate cell. 

 Ascogenous hyphae are not formed, but both nuclei of the single binucle- 

 ate ascogonial cell fuse in the mother cell and go through several mitoses 

 (up to ten), whereby the number of nuclei mounts to over 1,000. Mean- 

 while this fertile ascogonial cell has developed to a thick-walled ascus, 

 which at maturity contains over 1,000 ascospores, and whose top shows 



