IQ [I Morphologie, Physiologie, Biologie, Teratologie. 229 



685. Bonnier, G., Matrnchot, L. et Combes, R. Recherches sur la 

 dissemination des germes microscopiques dans l'atmosphere 

 (G. R. Acad. Sei. Paris, CLII, 1911, p. 652—659, 1 fig.) 



Eine Vorrichtung zum Zählen der in der Luft suspendierten Pilzkeime 

 wird beschrieben. Im Walde werden mehr Keime gefunden als auf offenem 

 Terrain; nach oben nimmt die Zahl der Keime ab, jedoch nicht so schnell wie 

 die der Bakterien. Küster. 



686. Brown, W. H. The development of the ascocarp of Lachnea 

 scutellata. (Rotan. Gazette, LH, 1911, p. 275—305, tab. IX, 51 fig.) 



Verf. fasst die Ergebnisse seiner interessanten Studie wie folgt zu- 

 sammen : 



The nature ascocarp of Lachnea is disk-shaped. The hymenium forms 

 the upper surface, while the rim and lower surface are covered by a thick- 

 walled cortical layer. The center is composed of rather loosely interlacing 

 hyphae. 



The ascogonium is the penultimate cell of a row of about nine. 



The ascogonium in early surrounded by vegetative hyphae, the outer 

 of which from the first part of the cortex, while those around the ascogonium 

 remaine active and give rise on one side to more of the cortex and on the 

 other to hyphae which will produce paraphyses. "When a part of the cortex 

 is once formed, the developmeut of the hyphae composing that part ceases. 

 The cells between the cortex and hymenium, however, remain active and add 

 to the cortex and to the hyphae which produce paraphyses. 



The ascogonous hyphae are large and brauch profusely. At the ends 

 of these are formed typical hooks, consisting of binucleate penultimate and 

 uninucleate ultimate and antepenultimate cells. The two nuclei of a penulti- 

 mate cell may fuse to form the nucleus of an ascus, or they may divide and 

 give rise to the four nuclei of another hook. The uninucleate ultimate cell 

 usually grows down and fuses with the antepenultimate cell, after which the 

 two nuclei may give rise to the nuclei of another hook, or they may fuse to 

 form an ascus. 



When the hymenium is first formed, it is covered by the younger setae 

 of the cortex, but as its diameter is increased and its level raised by the 

 multiplication of the number of asci and paraphyses, it comes to be exposed. 



No fusion of nuclei was observed in either the ascogonium or asco- 

 genous hyphae, except where two nuclei fuse to form the primary nucleus of 

 an ascus. 



The nuclei of the ascogonium and ascogenous hyphae appear to be 

 entirely similar except for size, and the same number of chromosomes, five, 

 persitst throughout their divisions. When the chromosomes are first formed, 

 they are frequently grouped in a mass resembling a second nucleus. The 

 chromosomes become connected with a centrosome which was not apparent 

 during the resting stage. This centrosome divides, and the two daughter 

 centrosomes come to be situated at the poles of the spindle. At metaphase 

 the five chromosomes divide, and at anaphase five pass to each pole. The 

 daughter nuclei are usually organized at some distance from each other, but 

 sometimes they are so close together that they resemble fusing nuclei. 



The first division in the ascus is teterotypic. Synizesis is produced by 

 the contraction of a Single spireme. After synizesis the spireme splits longi- 

 tudinally. The two halves come together again, after which the spireme 



