274 



Fig. 131. — Diagram showing stages in the development of an angiocarpic apothecivim, 

 e.g. that of Ascobolus stercorarius. The hyphae are represented by short hnes 

 the direction of which indicates the course of the main hyphae in the different 

 tissues. The ascogenous hyphae are represented by short thick hnes diverging 

 from the ascogonium which is drawn as a circle near the base of the apothecium 

 solely for reference ; actually it is obliterated by the growth of the surrounding 

 tissue at an early stage in development. Asci are drawn in successive stages 

 at the margin of the hjTnenium in g and h to indicate the radial growth of the 

 ascogenous hyphae, but no attempt has been made to show similarly their 

 intercalary growth. The cortical parenchjTna is shown by means of thick 

 well-spaced lines without special direction except at the margin, for the palisade 

 arrangement is commonly lost in the mature tissue. Hyphae which grow from 

 the miderside of the apothecium as excrescent cells into the substratum and 

 which constitute a secondary mycelium are shown by means of a few longer 

 lines, a and b, hyphae growing upwards and env-eloping the ascogonium ; c, 

 a ball of interwoven hyphae surrounding the ascogonium ; d, tissue differentia- 

 tion has begun, the cortex is distinguishable ; e, a mucilage cavity has formed 

 in the upper part of the spherical mass internal to the cortex, and a palisade 

 layer of hyphae is growing upwards into it, also ascogenous hyphae are growing 

 from the ascogonium toward the palisade layer ; /, the palisade layer can now 

 be seen not only on the floor but on the sides of the mucilage cavity, and the 

 hyphae which compose it are being converted into paraphyses ; g, the internal 

 tissues, by expanding, have now ruptured the cortical sheath which formed the 

 roof of the mucilage cavity, the hymenium has thus become exposed, and the 

 ascogenous hyphae have given rise to asci which are pushing upwards among 

 the paraphyses ; the primary parts of the apothecium have now been com- 

 pletely formed ; h, the secondary period of development has begun for marginal 

 growth is now taking place, the marginal hyphao are developing sympodially 

 giving rise to paraphj'ses above and cortical cells below. Drawni by E. J. H. 

 Comer and published by him in Trans. Brit. Myc. Soc., Vol. XIV, 1929. 



