226 Algae. — Fungi, Bacteria und Pathologie. 



reactions for chromatin and may be a modification of that sub- 

 stance. The heterocyst oi Cylindrospermiim will develop into 

 a Spore if it gets sufficient nutriment and hereditary material 

 passed into it irom the other cells. 



14. Spores are formed in Oscillarla from groups of cells, 

 usually two, but it may be one, three or four. These fuse by 

 the absorption of their partition walls. The growth of the spore 

 is effected by substances passed into it from the other cells. 

 The spores of Cylüidrospennum are formed from a single cell 

 which divides, the end cell becoming a heterocyst and the se- 

 cond cell the spore. It also receives substances from the other 

 vegetative cells. 



15. The cell wall is composed of ceilulose in its earlier 

 stages, but iater becomes impregnated with or modified into 

 some substance akin to fungus ceilulose. 



16. The cell wall is laid down as microsomata, in lamellae 

 on the inside of the cell wall. One such lamina is laid down 

 at each division. Thus every succeeding lamina from within 

 outward will Surround twice the number of cells as the pre- 

 ceding one, as shown in Fig. 94. 



17. In Oscillarla the outer laminae are dissolved off by 

 the water. In Nostoc they swell collectively into a jelly which 

 is permanent, while in Lyngbya the jelly remains as it was 

 deposited, in thin tough layers. J. M. Macfarlane. 



BOURQUELOT, Em. et H. Herissey, Sur la trehalase; sa pre- 

 sence generale dans les Champignons. (C. R. 

 Acad. Sc. Paris. T. CXXXIX. 21 nov. 1904. p. 874—876.) 



Le trehalose est aussi generalement repandu chez les 

 Champignons que le sucre de canne chez les Phanerogames, 

 les Fougeres et les Miisclne'es. L'utilisation du premier est 

 subordonnee ä la presence de la trehalase, comme celle du 

 second Test ä la presence de l'invertine. L'analyse des diverses 

 parties des fruits des Hyme'nomycetes demontre, en effet, que la 

 trehalase est un enzyme generalement present dans les tissus 

 des Champignons; l'epoque de sa presence et celle de sa 

 disparition sont souvent en rapport etroit avec Celles de l'utili- 

 sation du trehalase ou de l'emmagasinement de ce dernier sous 

 forme de matiere de reserve. Paul Vuillemin. 



QuiLLiERMOND, A., Recherches sur la germination des 

 spores chez quelques Levures. (C. R. Acad. Sc. 

 Paris. 5. dec. 1904. T. CXXXIX. p. 988—990.) 



La conjugaison des spores, frequente chez les Saccharomyces, fait 

 defaut chez les Schizosaccharoniyces, oü la conjugaison precede la for- 

 mation des asques. Lepeschkin avait cru observer une exception 

 chez le Seh. Mellacei. C'etait, selon Guiliiermond, une illusion 

 produite par l'emission d'un bourgeon abortif en un point de la spore 

 plus ou moins distant du tube gerniinatif principal. 



La fusion de 2 spores et de leurs noyaux , reguliere chez le 

 Saccharomyces Ludwigii, n'interesse plus que la moitie des spores chez 



