ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 427 



well as by night, but is not tbe result of previous insolation. The 

 author regards it as due not to any parasite or other extraneous organism, 

 but to a process of oxidation in the tissue itself, dependent either 

 directly on respiration or on a secondary process intimately connected 

 with respiration. 



Hymenoconidium.* — Under the name Hymenoconidium petasatum 

 Herr H. Zukal describes a remarkable hymenomycetous fungus, found 

 on rotten olive-berries and leaves, in which the formation of the stipe 

 is sometimes entirely suppressed, but the spores are still formed in the 

 normal manner, the hymene being then sessile upon the substratum and 

 remarkably resembling the aggregation of stylospores in the Uredineas. 



M. V. Fayod f believes the fungus thus described to be simply a 

 young state of Marasmius hygrometricus. 



Mycetozoa. 



Tylogonus Agavse. J — Under this name M. S. Miliakaris describes 

 an organism endophytic in the leaves of an Agave. It is found in the 

 form of a white plasmode in the palisade-tissue beneath the epiderm, 

 which the author believes to belong to a Myxomycete. The threads of 

 which the plasmode is formed are surrounded by a gelatinous envelope, 

 and the author states that the spores are formed and multiply by 

 division within the cells of the host. 



Protophyta. 

 a. Scliizopliycese. 



Scenedesi]ius.§ — M. E. De Wildeman reviews the described species 

 of this genus, which are very difficult to define, from the number of 

 intermediate forms. The presence or absence of horns cannot be re- 

 garded as a specific character. One or two forms display a rose-tint in 

 the cell-membrane, similar to that of some species of Pediastrum. 



Mediterranean Diatoms.]] — M. Peragallo describes in detail the 

 diatoms found by him in the bay of Villafranca on the coast of 

 the Department of Alpes-Maritimes, obtained from the deep-sea, from the 

 bottom by dredging, from algae to which they adhere, and from the 

 stomachs of fishes and other marine animals. The deep-sea species are 

 characterized by the comparatively small development of the siliceous 

 coat, and consequently by their susceptibility to be destroyed by acids. 



In the division of the Diatomaceae into the larger groups, the author 

 holds it to be a mistake to depend too much on the characters to be 

 drawn from the endochrome, as proposed by Petit. These characters can 

 only be used with great caution in the case of marine diatoms, and not 

 at all in fossil species. If also, as stated by M. Petit, the differences in 

 the arrangement of the endochrome are always correlated with differ- 

 ences in the structure of the valves, this renders the former unnecessary. 

 The author prefers a combination of the systems of classification of 

 Petit and Pfitzer with those of H. L. Smith, Grunow, and Cleve, based 



* Bot. Ztg., xlvii. (1889) pp. 61-5 (1 pi.). Cf. this Journal, ante, p. 99. 

 t T. c, pp. 158-9. 



X 'Tylogonus Agavse. Ein Beitr. z. Kenut. d. niedern endophytischen Pilze,' 

 4to, Athens, 1888, 14 pp. and 1 pi. See Bot. Centralbl., xxxvii. (1889) p. 84. 

 § Bull. Soc. E. Bot. Belg., xxvii. (1888) part i., pp. 71-9 (1 pi.). 

 II Bull. Soc. Hist. Nat. Toulouse, xxii. (1888) pp. 13-100 (5 pis.) 



