ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 273 



phenomena of this plant, which he finds to agree in every important 

 point with those of P. vulgaris. The glands are of two kinds, stalked 

 and sessile. The stalked glands consist of a basal cell projecting 

 above the epidermis, a 1-4-celled stalk, and a hemispherical columella, 

 to which is attached the glandular structure, in the form of a cap, and 

 consisting of a layer of cells arranged radially. The sessile glands 

 have a similar structure, but want the stalk ; the columella is conical, 

 and the gland does not project above the epidermis by more than one- 

 half. They occur also on the under side of the leaf, but are there 

 not so fully developed. 



Asparagin.* — According to M. Meunier, if asparagin is heated 

 with strong potash-ley, a portion of the nitrogen is eliminated as 

 ammonia ; and the quantity of asparagin can be determined by the 

 estimation of this ammonia. By this method the author claims to 

 have confirmed some previous statements with regard to the physio- 

 logical purpose of asparagin. The quantity formed on germination 

 varies with the duration of the germination, and with the nature of 

 the seed. In the first period of germination, the same quantity 

 of asparagin is formed in the light and in the dark ; subsequently it 

 accumulates in etiolated plants, and disappears in those exposed to 

 light. 



Diseases of Plants.f— Professor B. Frank has published the first 

 portion of a very useful and complete handbook on the diseases to 

 which plants are subject ; those caused by fungi being treated with 

 especial detail, and with regard to all the newest observations. 



B. CRYPTOGAMIA. 



Classification of Thallophytes.f — Professor De Bary reviews the 

 classifications of Thallophytes proposed by Cohn, Sachs, Winter, 

 Eichler and others, and suggests a new scheme differing somewhat from 

 them all. Sachs's system, depending on the one character alone of the 

 sexual organs, he considers too precise and artificial, like that of 

 Linnaeus for flowering plants; while Cohn's primary division into two 

 groups only will not bear examination. De Bary's proposed classi- 

 fication is into eight primary groups, viz. : — ■ 



1. Chlorophycece (corresponding nearly to Thuret's group of that 

 name); including all chlorophyll-green thallophytes with polysym- 

 metrical zoospores, and reproduced also by zygospores or oospores; 

 including Hydrodictyon, Ulothrix, Botrydium, Acetabularia, (Edogonium, 

 ColeocJicete, &c. The structure of the thallus is extremely variable, 

 and the sexual reproduction is either isogamous, by the conjugation of 

 similar gametes, or oogamous, by the fecundation of an oosphere by 

 antherozoids. Between these two modes there is every stage of 

 transition ; nearly allied forms, like Eudorina and Pandorina, some- 

 times differing in this respect. The highest position among the 



* 'Annales agronomiques,' vi. (1880) p. 275. See Bot. Centralbl., i. (1880) 

 p. 1461. 



t Frank, Dr. B., ' Die Krankheiten der Pflanzen.' IteHiilfte. Breslau, 1880. 

 See also infra, p. 282. 



X Bot. Ztg., xxix. (1881) pp. 1-17 and 34-6. 



