340 Cytologie und Befruchtung. 



wurde die Art aber untersucht weil in Petrischalen, welche um- 

 gekehrt hingestellt wurden (also mit der Gelatineplatte nach 

 oben, dem Deckel nach unten gerichtet), ein Bild der Culturen 

 auf dem Deckel entstand. Die Ursache dieser Erscheinung 

 wurde theilweise in Verflüssigung der Gelatine, theilweise in 

 Gasbildung gefunden. Näheres mag in der Originalarbeit nach- 

 gelesen werden. Went. 



Land, W. J. G., Spermatogenesis and Oogenesis in 

 Ephedra trifurca. (Botanical Gazette. Vol. XXXIII. 1904. 

 p. 1 — 18. Plates I— V.) 



Beginning with the organogeny of the flowers, the writer 

 gives a detailed account of spermatogenesis and oogenesis up 

 to the shedding of the pollen and formation of the egg. When 

 the pollen is shed, the male gametophyte consists of two pro- 

 thallial cells, a stalk cell, a body cell, and a tube nucleus. Both 

 prothallial cells are presistent but only the first is cut off by 

 a wall. The primary spermatogenous is surrounded by a mem- 

 brane and when the nucleus divides, the resulting stalk cell and 

 body cell continue to be surrounded by the membrane but do 

 not become separated from each other by a wall. 



The megaspore mother-cell gives rise to three or four 

 megaspores, the lower one of which is functional. At the first 

 division of the megaspore nucleus the daughter nuclei show 

 polarity. Nuclei are parietally placed from the first and simul- 

 taneous, free nuclear division continues until there are 256 free 

 nuclei before walls begin to appear. The archegonial region 

 consists of loose and rather large cells, while the antipodiat 

 region is more compact and serves as an haustorial and storage 

 tissue. No wall is formed between the ventral nucleus and the 

 egg. The egg nucleus takes a position midway in the cyto- 

 plasm of the archegonium and surrounds itself with a mem- 

 brane comparable to that which invests the egg in Angiosperms. 

 The gametophyte number of chromosomes is twelve. 



The apex of the nucellus breaks down, forming a pollen 

 Chamber and exposing the necks of the archegonia to the air, 

 so that the pollen is brought into direct contact with the female 

 gametophyte. 



A succeeding paper will deal with fertilization and embryo- 

 geny. Charles J. Chamberlain (Chicago). 



Ruhland, W., Studien über die Befruchtung von 

 Albugo Lepigonl und einiger Peronosporeen. (Jahrb. f. 

 wiss. Bot. Bd. XXXIX. 1904. p. 135.) 



Albugo (Cystopus) Lepigoni ist diejenige Art der Gattung, 

 bei welcher die Reduction in der Zahl der Eikerne am weitesten 

 fortgeschritten ist, indem nur einer der zahlreichen Kerne aus 

 dem Periplasma in die Oosphaere übertritt, während bei andern 

 Arten der Gattung entweder sehr zahlreiche weibliche Kerne 



