Cytologie und Befruchtung. — Descendenz und Hybriden. 165 



In the present paper the results of a further investigation 

 are recorded, the species studied being A. De Baiyana 

 Humphrey and A. polyandra Hildebrand. The author shows 

 fertilization to take place in both, and in A. De Baryana he 

 traces the entry of the sperm nucleiis into the oosphere, and 

 the fusion of the male and female nuclei. 



In the oogonium and antheridium a first mitosis is known 

 to take place, the discovery of a second division of some of 

 the daughter nuclei is recorded. At this stage the number of 

 chromosomes is apparently rediiced from 8 to 4. The oogonium 

 contains many oospheres; the supernumerary nuclei undergo 

 degeneration before the oospheres are distinctly formed. Each 

 oosphere is uninucleate and possesses a well defined centro- 

 some, astrophere, and coenocentrum-like body designated the 

 ovocentrum. 



A distinct centrosome and astrophere is acquired by the 

 sperm nucleus, soon after its entry into the oosphere; as the 

 sperm moves inwards towards the nucleus these bodies are 

 directed outwards. The fusion of the gametonuclei takes place 

 after the disappearance of the ovocentrum, chromosomes and 

 astropheres. 



Of special interest is the presence of the centrosome and 

 astrophere of the male nucleus though no significance is traced 

 to it in the act of fusion. A. D. Cotton (Kew). 



TSCHERMAK, E., UeberkünstlicheAusIösungdesBlühens 

 beim Roggen. (Ber. d. d. bot. Ges. 1904. Heft 8. p. 

 445—449.) 



Die Lodiculae bewirken bei Roggen das Oeffnen der Spelzen 

 auch schon nach mechanischer Reizung^ sie sind ein mechanisch 

 reizbares Turgescenzorgan. Oeffnen der Blüthe, Austreten der 

 Staubblätter und Platzen der Beutel kann bei blühreifen Aehren 

 einige Stunden bis 1 — 2 Tage vor dem unbeeinflussten Aufblühen 

 von gleich entwickelten Aehren durch Streichen der Aehren 

 zwischen den Fingern, Schütteln der Halme, Aneinanderschlagen 

 der Aehren etc. bewirkt werden. Unterbleibt mechanische Reizung, 

 so tritt doch auch Aufblühen ein. Ein Weizen-Roggenbastard 

 verhielt sich künstlichen Eingriffen gegenüber so wie Roggen. 

 ^ C. Fruwirth. 



Shull, G. H., Place-constants for Aster prenantholdes. 

 (Bot. Gaz. Vol. XXXVIII. p. 333—375. fig. 1 — 18. Nov. 

 1904.) 



Statistical study of the .,place mode" of the bracts, rays, 

 and disk-florets of the inflorescence of this plant. Twelve 

 successive collections were made from the same spot in the 

 season of 1903 and it was found that the earliest collections 

 had low mean numbers, that the mean values then leaped 

 <iuickly to a maximum, falling off gradually to near the end of 



