ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 223 



of different grasses, Prof. F. Darwin * has been able to localise the geo- 

 tropic sensitiveness chiefly, though not exclusively, in the cotyledon. 



Miss D. F. M. Portz f confirms Czapek's statement J that the maxi- 

 mum of geotropic curvature is reached when an organ deviates from the 

 horizontal at an angle of 45° in a downward direction. 



Motile Apparatus of Mimosa.§ —According to Prof. A. Borzi, the 

 roots of Mimosa pudica are capable of transmitting movements of irri- 

 tation although destitute of any special organs of sensitiveness; and the 

 same is the case with the leaves of some Leguminosae. In the tissue 

 of the motile organs of the leaves of Mimosa is a structure not found 

 elsewhere in the plant. The protoplasts are surrounded by peripheral 

 fibrillar extensions, which penetrate through the delicate orifices in the 

 cell- walls, placing them in intimate connection one with another. This 

 motile apparatus is attached to every leaf of the plant, and sends out 

 prolongations which extend to the whole plant, even to the root-system. 

 But it is in the leaves only that the sensitive apparatus comes into 

 contact with the environment. The only way here for the conduction 

 of the irritation is through the epiderm, whether of the leaflets, of the 

 mid-rib, or of the cushions. The minute structure of these various 

 parts is described in detail. The protoplasm of the sensitive organ 

 contains a large amount of saccharose in solution, which accounts for its 

 high osmotic properties. 



(4) Chemical Changes (including Respiration 

 and Fermentation). 



Synthesis of Albuminoids. || — Herr W. Palladin asserts that the 

 nitrogenous organic substances in plants may originate in several ways. 

 Besides the intermediate products of the primary synthesis of albu- 

 minoids, we may also have products of the decomposition of albuminoids ; 

 intermediate products of the regeneration of the decomposition-products ; 

 and various special products of the breaking up of albuminoids. The 

 decomposition of albuminoids takes place only in growing organs. In 

 Viva Lactuca and Enteromorpha intestinalis he found asparagin, but no 

 tyrosin. Tyrosin cannot, therefore, be the first stage in the primary 

 synthesis of albumen. Asparagin and tyrosin are simply products of 

 the decomposition of albuminoids. In Salicornia herbacea he found 

 neither asparagin nor tyrosin ; in the leaves of Bobinia Pseudacacia 

 very little asparagin and no tyrosin ; in the leaves of Dahlia variabilis 

 (in August) neither asparagiu nor tyrosin. 



Enzymes.1T — Herr J. Griiss gives further details of the properties of 

 the enzyme of Penicillium glaucum. It possesses the power of energeti- 

 cally splitting up cane-sugar, but has a less powerful action on starch 

 and reserve-cellulose ; it has not the properties of an oxydase. Malt- 

 diastase, on the other hand, plays the part of a y-oxydase ; it acts 

 energetically on starch, less so on cane-sugar, and only very slowly on 

 reserve-cellulose. 



* Arn. of Bot., xiii. (1899) pp. 567-74 (1 pi.). t Tom. cit., p. B20. 



t Cf. this Journal, 1895, p. 454. 



§ Kiv. Sci. Biol. Palermo, 1899. fasc. 4, 39 pp. See Bot. Centialbl.. lxxx. (1899) 

 p. 351. || Russian, Oliarkow, 1898. See But. Centralbl. lxxx. (1899) p. 17. 

 f Festschr. f. Scliweiulener, 1899, pp. 184-201. (1 pi.). 



