ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 337 



described. Claussen follows Harper in deciding that the formation of 

 the fruit is due to a sexual process. Ascogonia and antheridia are formed, 

 and numerous nuclei pass over from the antheridium to the ascogonium 

 and pair with the female nuclei. No fusion takes place, but the con- 

 jugate pairs pass into the numerous hyphae that arise from the ascogonium 

 with subsequent conjugate division. Tlie descendants of the two nuclei 

 finally fuse in the ascus, but a conjugate pair remains behind, which 

 may divide again, furnishing nuclei for another ascus, with, in addition, 

 a reserve pair. There is no second fusion in the life-cycle of Pyronema. 

 The first division in the ascus is heterotypic. There is alternation of 

 generations in Pyronema as in other plants. Spore, mycelium, and 

 sexual organs represent the gametophyte. As Pyronema does not form 

 gamete cells, the ascogenous hyphre or sporophyte generation is not 

 sharply differentiated from the gametophyte. Instead of one nucleus 

 with the double number of chromosomes, the sporophyte has a pair of 

 nuclei, male and female, that divide conjugately ; the two together 

 represent the doubling of the chromosomes. A young ascus, with the 

 fused nuclei, is to be regarded as a spore-mother-cell. And in the 

 nucleus there are as many double chromosomes as there were single 

 chromosomes in the gametophyte. The further nuclear divisions in the 

 ascus are without signification from the point of view of alternation of 

 generations. 



Biological and Morphological Study of Aspergillus.* — G-. Bainier 

 and A. Sartory have made elaborate cultural studies of three species of 

 Aspergillus that form coloured pigments : A. mollis is a well-developed 

 form with fairly large conidia ; the perithecia were produced in large 

 numbers. It grows on all the usual media employed in the culture of 

 fungi. It does not liquefy gelatin, etc., and secretes a red pigment. 

 A. mutabilis also grows in the usual media. It undergoes manv colour 

 changes from canary yellow to a deeper colour, then to green, finally to 

 greenish-black. The peritliecia are freely formed. It does not liquefy 

 gelatin, secretes iuvertin, and does not form alcohol. It secretes a red 

 pigment. A. repandus is at first green, becortiing darker, and later 

 coloured violet in spots \vhere the pigment which it forms has become 

 fixed in the filaments. It \z a vigorous species which also forms 

 perithecia. Full details are given of the different cultures. 



Monograph of Erysiphacese.f — Gino Pollacihas made a study of the 

 Italian representatives of this family of Pyrenomycetes. He divides 

 them into two sections, Erysiphacefe with five families, and Phyllactinia 

 with one only. They are easily distinguished by the base of the appen- 

 dages which in the latter are inflated. Pollaci has redescribed all the 

 genera and species, giving careful measurements of spores, etc. The 

 synonymy is full, and a copious bibhography is published. The plate 

 contains drawings of each genus described. 



Study of Gloeosporium fructigenum.| — 0. Schneider-Orelli has ex- 

 amined and contrasted the growth of this fungus on apples in Switzerland 



* Bull. Soc. Mycol. France, xxvii. (1911 j pp. 453-68 (3 pis.). 

 t 1st. Bot. Univ. Pavia, ser. 2, ix. (1911) pp. 151-81 (1 pi.). 

 X Centralbl. Bakt., xxxii. (1912) pp. 459-67. 



