ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 77 



Sauvageau, C. — Le verdissement des huitres par la diatomee bleue. (The green 

 coloration of oysters by the blue diatom.) 

 [A long treatise, dealing exhaustively with all past work on the subject, 

 and giving a bibliography of 91 works.] 



Soc. Sci. d'Arcachon, x. (1907) 128 pp. 



Fungi. 



(By A. Lorrain Smith, F.L.S.) 



Cytology of Synchytrium.* — S. Kusano selected for this research a 

 still undescribed species, Synchytrium Purerar'm. He devoted his 

 attention to the relation between parasite and host, and comparisons 

 are drawn between the results obtained and those of other workers in 

 the same field. In the species examined no resting spores are formed, 

 but sporangia can pass the winter within the tissue of the hosts and 

 produce swarm-spores in spring. These spores probably enter by the 

 stomata and find their way to non-chlorophyll, sub-epidermal cells. 

 The parasite grows within the cells of the host, absorbing the walls and 

 those of the neighbouring cells, or compressing them to make room for 

 its large size, and thus, from being intracellular, comes to occupy an 

 intercellular lysigenetic space. When growth finishes, a hyaline mem- 

 brane is formed round it, and the whole contents break up into spores, 

 which are ejected by the swelling up of the surrounding host-cells. 

 Kusano found that the cytoplasm and nuclei of the host remained 

 healthy, and though they eventually disappear, that is due probably to 

 self -disorganisation . 



l &^ 



Specialisation in Erysiphacese.-f — G-. M. Reed selected Erysiphe 

 Oichoracearum for a series of experiments in this field. He recalls the 

 work done on these lines, and gives his own results. The spores of the 

 fungus were sown on 23 varieties of Cucurbitaceae belonging to three 

 different genera. There was no difficulty in obtaining inoculation in 

 any instance ; the fungus spores taken from any species when trans- 

 ferred, grew at once on any other species. He contrasts his results 

 with those of Salmon, who found some five physiological species in 

 Erysiphe graminis. He considers that the species he was dealing with 

 probably represents a less primitive form than the one on grass, and 

 that it has become adapted to a larger number of hosts. 



Parasitism of Valsa.J — Spieckerman examined a number of pear- 

 trees that had died, and found the branches beset with Valsa cincta. 

 In cultures he produced pycnidia, but attempts at infection in the open 

 gave only negative results. He concludes that the Valsa is a wound 

 parasite, that it gains entrance, and then penetrates deeply into the 

 sound tissue. The affected trees were all in a moist locality. An 

 epidemic among cherry-trees was traced to the action of a Cytospora, 

 also a "weak parasite," and the author includes these, and probably 



* Centralbl. Bakt., xix. (1907) pp. 538-43 (1 pi.). 



t Trans. Wis. Acad. Sci. Arts and Letters, xv. (1907) p. 527. See also Bot. 

 Centralbl., cv. (1907) p. 536. 



X SB. Nat. Ver. Preusz. Rheinl. Westf., 1907, pp. 19-27. See also Ann. Mycol., 

 v. (1907) pp. 379-80. 



