606 Algae. — Fungi, Myxomyceten , Pathologie. 



Schmidle, W., Zur Kenntniss der Planktonalgen. (Hedwigia 

 XLV. Heft 1. p. 34—35. 5 Texttig. 1905.) 



Verf. beschreibt eine neue Algengattung Didymogenes, die im 

 Plankton von Roxheim in der Pfalz von Laute rborn gesammelt 

 wurde. Die Gattung steht Actiuastntui nahe. Die Art wird Didyiuo- 

 genes palatma genannt. In demselben Material fand sich auch Laii- 

 terhorniella elegantissinia. Von dieser gibt Verf. eine Abbildung nach 

 gefärbtem Material. Diese Alge stimmt im Zellbau und in der Zell- 

 teilung mit Didymogenes überein, sodass auch diese Alge in die 

 Nähe von Actinastrutn gehört. Heering. 



Yamanouchi, Shiqeo, The Life History of Polysiphonia violacea. 

 (ßotanical Gazette. Vol. XLII. p. 401-449. Plates' 19-28. 1906.) 



This remarkably detailed cytological investigation of the life 

 history of Polysiphonia shows a definite alternation of generations, 

 the antheridial and carpogonial plants constituting the gametophyte 

 and the tetrasporic plant the sporophyte. The authors own summary 

 of the evidence is as follows: "1. The carpospore on germination 

 shows 40 chromosomes, and 40 chromosomes appear in the vegetative 

 mitoses of the tetrasporic plant; so it may be inferred that tetra- 

 sporic plants come from carpospores. 2. The tetraspore on germination 

 shows 20 chromosomes, and 20 chromosomes appear in the vegetative 

 mitoses of the sexual plant; so it may be inferred that sexual plants 

 come from tetraspores. 3. The nuclei of the gametes (sperm and 

 carpogonium) contain each 20 chromosomes. The fusion nucleus 

 (sporophytic; in the fertilized carpogonium as a result has 40 chromo- 

 somes and gives rise to a series of nuclei in the central cell. Some 

 of these enter the carpospores, which are consequently a part of 

 the sporophytic phase to be continued in the tetrasporic plant. The 

 gametophyte nuclei in the central cell of the C3^stocarp with 20 

 chromosomes break down. 4. Tetraspore förmation terminates the 

 sporophytic phase with typical reduction phenomena, so that che 

 tetraspores are prepared to develop the gametophyte generation. 

 5. There is thus an alternation of a sexual plant (gametophyte) with 

 a tetrasporic plant (sporophyte) in the life history of PolysipJionia , 

 the cystocarp being included as an earh^ part of the sporophytic 

 phase". 



The trichogyne has a nucleus and should be regarded as much 

 more than a mere cytoplasmic extension of the carpogonium. 

 Chromosomes do not come directly from the nucleolus but from the 

 rearrangement of chromatin networks. There is present neither 

 centrosome nor centrosphere as such comparable with those of 

 Dictyota, Sphacelaria , Fuchs j Erysiphe and other forms. Cell division 

 is accomplished by a cleavage furrow which proceeds inward from 

 the peripher}^ of the cell. Charles J. Chamberlain (Chicago;. 



Istvänify, Gy. de, Sur le developpement du Botrytis cinerea. 

 (Aus den Res. sc. Congr. int. Bot. Vienne 1905. [Jena 1906] 

 p. 349—353.) 



Verf. giebt hier die Resultate seiner ausführlich in den Annales 

 de rinstitut central ampelologique royal Hongrois, Tome III Livr. 4 

 Budapest (1905) p. 183—360 veröffentlichten wichtigen Untersuchun- 



