226 Fortpflanzung. 



point is that in the hybrid P. floribunda isaheUina x P. kewensis, althongh the form er 

 has 9 chromosomes as the x number and| the latter 18 as x number, yet the ofi"spring 

 have only 18 chromosomes as 2 a; number. It appears probable that the 9 extra cbro- 

 mosomes are extruded from the nuclei of the embryo, as is known from the work of 

 Herbst and others to take place in Echinoderm hybrids. Gates (London). 



634) Farmer, J. B. (London, Royal College of Science), Telosynapsis and 

 parasynapsis. In: Annais of Botany, Bd. 26, Heft 2, S. 623—624, 1912. 

 This note points out the essential differences between the telosynaptic and 

 parasynaptic accounts of meiosis. It is no longer a matter of fundamental sig- 

 nificance whether the actual pairing of the chromosomes is end-to-end or side- 

 by-side. The important question at issue concerns the interpretation of the much 

 earlier stages of the heterotypic prophase. Are the parallel threads observed at 

 this time due to a split or an approximation ? The former view is supported by 

 the fact that 1. similar parallel threads are found in postmeiotic prophases where 

 they must be due to a split, and 2. that the parallelisms of the heterotype pro- 

 phase are very similar to those of the archesporial prophases. Gates (London). 



G35) Melhiis, I. E., Experiments on Spore Germination and Infection in 

 certain Species of Oomycetes. In: Wisconsin Agr. Expt. Stat. Research Bulletin 

 No. 15, S. 25—91, 1911. 



"The results obtained suggest that a chose relation exista between host vigor and 

 susceptibility (in infection) in that healthy plants are more susceptible than sickly or 

 abnormal ones." Bibliography. Pearl (Orono). 



636) Pearson, H. H. W. (South African College), On the microsporangium and 

 microspore oi Gnetum, with some notes on the structure of the inflores- 

 cence. In: Annais of Botany, Bd. 26, Heft 2, S. 603—620, 1912. 



Three species of Gnetum were studied. The inflorescence and the poUen develop- 

 ment are described. The reduced number of chromosomes appears to be 12 as in other 

 Gymnosperms. Gates (London). 



637) Foex, Les conidiophores des Erysiphacees. In: Reyue generale de Bota- 

 nique, Bd. 24, Heft 280, S. 210—207, 1912. 



L'auteur a e'tudie la formation des conidiophores chez les Erysiphacees, et il rapporte 

 ces organes ä quatre types. 1°. La cellule-base est ä la fois pedicelle et cellule gene- 

 ratrice de cellule-mere de conidias. 2". Un pedicelle unicellulaire porte une cellule mere 

 au-dessus de laquelle se trouve une chaine plus an moins longue de cellules destinees 

 ä se diflferencier directement en conidiee. 3"^. Le pedicelle est assez grele, et souvent plu- 

 ricellulaire. — Pour ie reste, la structure est comparable ä celle du 2. type. 4". Le pe- 

 dicelle, generalement pluricellullaire, peut bourgeonner pour constituer des conidiophores; 

 de plus, Tappareil conidien primaire s'insere, non pas au dessus d'un filament mycelien 

 externe et perpendiculairement ä la direction de ce dei-nier, ce qui est le cas chez toutes 

 les Erysiphacees, mais ä Fextretnite ou pres de l'extremite d'une hyphe endophytique. 



C. L. Gatin (Paris). 



638) Vill, K., Die Trüffeln. In: Naturwissenschaftliche Zeitschr. für Forst- und Land- 

 wirtschaft, Bd. 10, Heft 1, S. 22—43, 1912. 



Herleitung des Wortes „Trüffel". Arten, welche bei der Anzucht in Betracht kom- 

 men. Entstehung der Trüffeln, Versuche zur künstlichen Anzucht (Sporen, Zwischenwirte, 

 Trüffelammen, Kultur der Trüffeln), Eigentümlichkeiten im Leben der Trüifeln. 



Eckstein (Eberswalde). 



{>39) Yiala, P., et Pacottet, P. (Institut Agrouomique de Paris), Les ChlamydosporeB 

 du Black rot. In: Annales de la Soc. agrouomique, Bd. 29, Heft 4. Avril 1912. 

 Le Guignardia Bidivelli, Champignon qui cause la maladie du Black rot, presente 

 les modes de reproduction les plus varies. Les Chlamydospores, trös rares dans la nature 

 sont au contraire aisemeut obtenus dans les cultures de laboratoire. Les auteurs eta- 

 olissent que, dans la nature, la production de chlamydospores comcide toujours avec 

 des temperatures froides persistantes au moment de la vendange; de plus, ils n'appa- 



