on 



62 SUMMARY OF CURRENT RESEARCHES RELATING TO 



permeated by canals, which in the central portion are parallel to the 

 longitudinal axis, in the peripheral portion vertical to the surface. The 

 ultimate branches of the canals dichotomise freely. 



Platydorina, a New Genus of Volvocineae.* — Dr. C. A. Kofoid finds, 

 in the plankton of streams in Illinois, a colonial alga, which he makes 

 the type of a new genus of Volvocineae, under the name Platydorina 

 caudata g. et sp. n. The coenobe or colony is composed of 16 or 32 

 biflagellate cells, and is of a horseshoe shape, somewhat twisted on its 

 axis, and is remarkable for having at one end 3 or 5 projections or 

 tails, which are extensions of the gelatinous sheath. The following is 

 given as the diagnosis of the new genus :— Colony flattened, the two 

 faces compressed, so that the cells of the two sides intercalate ; flagella 

 upon both faces of alternate cells ; anterior and posterior poles of major 

 axis differentiated by the arrangement of the cells and by the structure 

 of the envelope ; long and short transverse axes differentiated by the 

 flattening of the colony ; cells similar, biflagellate, each with stigma, 

 chromatophore, and pyrenoid ; non-sexual propagation by repeated 

 division of all the cells, each forming a daughter-colony. The loco- 

 motion is chiefly in one direction. The author regards the ccenobe as 

 really a unit rather than a colony. 



A clavis follows of the genera of Volvocineae, Gonium, Stepha.no- 

 sphsera, Pandorina, Eudorina, Platydorina, Pleodorina, and Volvox. 



Fungi. 



Nitrogenous Constituents of Fungi, f — According to Herr E. 

 Winterstein, the chemical composition of Fungi differs in several 

 important points from that of flowering plants. In addition to carbo- 

 hydrates, the membranes contain a nitrogenous substance, chitin. Neither 

 in fresh nor in dried fungi (Boletus edulis, CantJiarellus cibarius, Agaricus 

 cawpestris) was the author able to isolate proteids. From B. edulis and 

 A. campestris leucin was crystallised, and the presence of tyrosin was 

 demonstrated by Millon's reagent. 



Effect of Deleterious Agents on Fungi.J — Mr. J. F. Clark has a 

 lengthy article on the toxic effect of deleterious agents on the germi- 

 nation and development of certain filamentous Fungi. Among the more 

 important results may be mentioned the following. 



Fungi are in general much more resistant to most deleterious agents 

 than the higher plants. In the case of mineral acids, a concentration 

 of from 200 to 400 times the strength fatal to the higher plants is 

 required to inhibit the germination of mould-spores under otherwise 

 favourable conditions ; but different species of fungi present very great 

 differences in their power of resistance to the various agents. Even 

 spores taken from the same pure culture may differ from one another in 

 this respect. The protoplasm of moulds is in general most sensitive to 

 the action of deleterious agents in the conidial stage. Hydrocyanic 

 acid is a very violent poison to moulds, while strychnine is nearly in- 

 nocuous. 



» 



* Bull. Illinois State Lab., v. (1899) pp. 419-40 (1 pi.). 



t Hoppe-Seyler's Zeitschr. f. Phys. Chem., xxvi. (1899) p. 438. See Beili. z. Bot. 

 Centralbl., ix. (1900) p. 167. 



% Bot. Gazette, xxviii. (1899) pp. 289-327, 378-404 (10 diagrams). 



