ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 247 



Reproductive Organs of Ascomycetes.* — C. Fiscli has made a 

 careful examination of the structure and development of the perithecia, 

 asci, and other reproductive organs of the following fungi : — Poly- 

 stigma rubrum and fulvum, Xylaria jpolymorpha, Claviceps purpurea, and 

 Cordiceps ophioglossoides, militaris, and capitata. The following are 

 the general results at which he has arrived. 



In the two species of Polystigma, the author has no doubt that in 

 the ascogonium with its trichogyne-threads on one hand, and in the 

 spermogonium on the other hand with its abstriction of spermatia, 

 we have sexual organs. The degeneration of the trichogyne, however, 

 takes place in a somewhat different way from that described by Stahl 

 in the case of Gollema. But at present we have no direct evidence 

 of any actual act of conjugation in the case of Polystigma. 



In Xylaria the asci are unquestionably formed in the perithecia 

 without the operation of any sexual organs ; they are purely vegetative 

 offshoots. This process is always preceded by the formation of 

 Woronin's hyph^e, which appear at first sight to have some analogy 

 with the scolecite of Ascoholus ; but in Xylaria these certainly have 

 no sexual function. 



In Claviceps and Cordiceps the complete disappearance of the 

 rudimentary and functionless ascogonium indicates the last stage to 

 complete apogamy. Claviceps does not show the least trace of sexual 

 organs ; the asci are formed within the perithecium by a true vege- 

 tative process. But this genus differs from all other stroma-forming 

 Pyrenomycetes that were examined, by a formation of true tissue in 

 the construction of the asci, analogous to that described by Bauke in 

 Pleospora. 



The Pyrenomycetes may be regarded as forming a series, the 

 highest forms of which exhibit a complete differentiation of sexual 

 organs, ascogonium, trichogyne, and spermatia ; while the lowest 

 forms are strictly apogamous. The function of the conidia, which 

 also occur in some simple Pyrenomycetes and Discomycetes, and 

 which are often confounded with spermatia, must still remain in 

 doubt. 



Fecundation of Achlya and Saprolegnia.f — N. Pringsheim 

 claims to have detected the mode in which the actual fecundation 

 of the oospheres of Achlya and Saprolegnia takes place. The fer- 

 tilizing tubes are stated by de Bary to remain always closed, and not 

 actually to coalesce in their growth with the oospheres. Pringsheim 

 states, however, that an intimate coalescence between the two does 

 take place. In the protoplasm of the antheridia and fertilizing tubes 

 are peculiar protoplasmic bodies distinguished by their greater 

 refrangibility ; they are larger than the fusiform nucleus, and 

 exhibit extremely slow and sluggish amoeboid movements. They 

 closely resemble the spermatozoids of MonohlepJiaris described by 

 Cornu, and are called by Pringsheim spermamoehce. They eventually 



* Bot. Ztg., xl. (1882) pp. 851-70 ; 875-97 ; 899-906 (2 pis.). 

 tISB. K. Akad. Wiss. Berlin, 1882, pp. 855-88. See Bot. Centralbl., xii. 

 (1882) p. 322. 



