826 SUMMARY OF CURRENT RESEARCHES RELATING TO 



closely entangled, but without an ascogonium being distinguishable ; 

 a small endogenous ball of slender hyphae being thus formed, which 

 continues to increase in size, and finally bursts through the cortical 

 layers which have bulged out into a spherical form. From this ball 

 a string of hyphae grows upwards, surrounded by a cylinder of thicker 

 hyphae derived, from the detached outer medullary layers of the sclero- 

 tium. These outer coarser hyphae form the cortical layer of the cup, 

 the inner bundle developes into the medullary layer of the stalk, and 

 later into the hymenium. The body thus formed is at first cylin- 

 drical ; the cortical hyphae diverge at their distal end, and thus form 

 a club-shaped structure; while the finer central hyphae converge 

 distally. In the middle of the bundle the hyphae cease after a time 

 to increase in length ; while the outer ones continue to grow, and 

 thus form an elongated cylinder. The wall of this canal is clothed 

 with the ascogenous ends of the hyphae. At a later period the canal 

 becomes wider above, becoming first funnel-shaped and the margin 

 then expanding flat, thus forming the well-known cups of Peziza 

 Fuckeliana. At first paraphyses only are visible on the disk ; the asci 

 are first formed in the centre, and gradually extend to the margin. 

 Usually several are formed on the thickened end of each hypha ; but 

 the ascogenous hyphae appear to have the same origin as the sterile 

 ones which become paraphyses. 



Development of the Sporangia of the Phycomycetes.* — M. Biisgen 

 describes the mode of development of the sporangia and of their zoo- 

 spores in the following genera of Phycomycetes : — Dictyuchus, Lepto- 

 vnitus, Saprolegnia, Achlya, Aphanomyces, Phytophihora, Cystopus, 

 Pythium, Peronospora, and Mucor. 



These exhibited several distinct modes of spore-formation. In 

 some cases a number of spores are developed within the sporangium 

 to more or less complete isolation. In these cases cell-plates are 

 formed, the entire contents of the sporangium dividing, but not always 

 simultaneously, into nearly equal portions. ■ The cell-plates then 

 partially or entirely deliquesce into a hyaline mass, finally disappear- 

 ing altogether. At the same time the structure of the protoplasm 

 contained in the sporangium changes ; it becomes more uniformly 

 granular and transparent, a large number of small round vacuoles 

 appearing at the same time. These partially disappear, and fresh 

 cell-plates are again formed. Each of the portions of protoplasm 

 separated by them contains one of the small vacuoles, and is the 

 protoplasm of the subsequent spores. The cell-plates either form 

 the cellulose-membranes of the spores or pass over into intercellular 

 substance. 



In Aphanomyces there are, however, no cell-plates ; and the mode 

 of formation of the intercellular substance presents a difficulty. It 

 may be produced in the way described by Strasburger in the case of 

 some swarm-spores, or it may be regarded, with de Bary, as a secretion 

 from the mature spores. 



An analogous production of temporary cell-plates has been 



* Pringsheim's Jahrb. f. wiss. Bot., xiii. (1882) pp. 253-85 (1 pi.). 



