ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 671 



tlic change proclucecl by res[)iration being compensated by other changes 

 resulting from diffusion. In addition to bubbles disengaged from inter- 

 cellular spaces in the interior of the plant, there are often others, always 

 very small, on the surface of submerged plants; tlicse result entirely 

 from the air dissolved in the water, and occur only on 2)lants without 

 intercellular spaces, especially on Algfe, The air in the intercellular 

 sjjaces is subject to constant variations of pressure. These intercellular 

 spaces are formed in the tissue at a very early period, occurring even 

 near the extremity of the cone of growth of the stt m. 



As a general result, the author states that there always exists air 

 dissolved in all the constituent parts of a submerged jjlaut, and that the 

 gas in every cell is subject to a uniform pressure, corresponding nearly 

 to that of the surrounding air. 



Absorption of Water by Leaves.* — In order to determine whether 

 plants can absorb water through their leaves, Herr W. Chmielewskij 

 arranged branches of a number of shrubs and trees, so that a portion of 

 their leaves was immersed in water, the remainder being exposed to the 

 air. In all cases except one, the leaves immersed in water remained 

 fresh for a longer period than those exposed to the air. The absorption 

 of water does not take place through the stomates, but equally through 

 both surfaces of the leaf ; the stomates remained filled with air. 



Changes of Substance and Force connected with Respiration.f — 

 Pursuing his investigations on this subject, Dr. H. Eodewald again finds 



CO 



the average value of the relationship — — ^ to be very near unity. In 



the case of the cabbage, which was especially the subject of investiga- 

 tion, the author believes deviations from this average to be due to 

 other chemical processes going on side by side with that of respiration. 

 An absorption of energy must necessarily take place in the conversion 

 of cellulose or phellog(;n into grape-sugar, since the heat evolved in 

 combustion is greater in the case of cellulose than in that of grape- 

 sugar. The same must be the case when grape-sugar is converted into 

 starch, and possibly also in the splitting up of albuminoids. 



y. General. 



Chlorosis.| — The disease of chlorosis, characterized by the pale 

 yellow colour of the leaves and the stunting of the branches, which is 

 very destructive to vineyards, is attributed by M. E. Petit to an excess 

 of moisture in the soil, tilling the cavities which ought to be full of air. 

 It is, in fact, the outward manifestation of the choking of the roots. 

 Various remedies are discussed. 



Vuillemin's Vegetable Biology.§— This work is divided into three 

 parts : — The life of the cell ; the life of the individual ; and the social 

 life of plants. The first chapter is devoted to the cell in general. The 

 cell is formed by two kinds of microsomes, cytosomes and caryosomes, 



* Arb. Neu-russ. Natuif. Gedell., xiii. (1888) pp. 128-31:. See Bot. Centralbl 

 xxxviii. (1889)p. 790. 



t Jahrb. f. Wiss. Bot. (Pringsheim), xx. (1889) pp. 261-91. Cf. this Journal 

 1888, p. 771. 



X 'La clilornse: Rech. d. ses causes et rl. ses remedes,' Bordeaux 1888 See 

 Bull. See. Bot. France, xxxvi. (1889), Rev. Bil.]., p. 84. 



§ ' La Biulogie ve'getale,' 16mo, Pans, 1888, 360 pp. and 82 figs. 



