ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 523 



destroyed all power of reaction, causing copious formation of sugar ; 

 absolute alcohol destroys life in an extremely short time. Exposure 

 for twenty-four hours to a stream of carbonic acid destroys the life of 

 the cells. Hydrochloric acid and citric acid produce an injurious 

 effect almost immediately. The power of resistance to alkalies is 

 much greater. Immersion for oue hour in a 10 per cent, solution of 

 sodium chloride destroys most of the cells. Metallic poisons act 

 more slowly ; some cells still show signs of life after immersion for 

 two hours in 1 per cent, solution of sugar of lead, or for twelve hours 

 in • 1 per cent, of arsenic acid, or for twelve hours in 1 per cent, of 

 zinc vitriol. Of organic poisons, gallic acid, pyrogallol, resorcin, 

 hydrochinon, in 1 per cent, solutions, act rapidly, destroying life in 

 a few hours, as also • 2 per cent, salicylic acid, and 1 per cent, 

 carbolic acid in one hour. Alkaloids, acetate of strychnin, chinin, 

 and very dilute veratrin do not prevent the reaction, although the 

 structure of the protoplasm is destroyed ; 1 per cent, sulphuric acid 

 destroys the power of reaction. 



Apical Cell-growth in Phanerogams.* — In order to determine 

 the much-disputed cause of the want of a special apical cell in 

 flowering plants, G. Haberlandt has closely investigated the process 

 of apical cell-growth in the following instances : the cell-divisions of 

 the cortical parenchyma in the laburnum and in the trichomes of the 

 leaf-stalk of Begonia Bex ; the formation of the stomatal apparatus 

 and neighbouring cells in Mercurialis and in Crassulacese ; the cell- 

 divisions in the formation of the hypodermal bast-cambium bundle 

 in the leaves of Typha latifolia ; the formation of the midrib of the 

 leaf of Elodea canadensis ; and the formation of the leaves and axillary 

 shoots of Ceratophyllum demersum. 



The general conclusions arrived at are, that in Phanerogams there 

 are tissues and masses of cells of very different extent and significa- 

 tion, which have been formed by apical cell-growth. It may be 

 either rows of cells only that increase by apical growth, as in the 

 first and second of the above instances, or plates of cells, as in the 

 third, or finally masses of cells may exhibit apical cell-growth, as 

 in the two last. Each of the three tissue-systems of Hanstein, der- 

 matogen, periblem, and plerome, grows at first by means of a single 

 apical cell. 



Development of Bordered Pits.t — E. Eussow has carefully in- 

 vestigated the development of bordered pits, and of the membrane of 

 wood-cells, more particularly in the Abietineae. The general con- 

 clusions at which he has arrived are the same as those of Sanio. 

 The growth of the wall of the border points to the interpretation of a 

 kind of secondary division-wall, as if a free membrane were excreted 

 on the upper side of the protoplasm. 



* Haberlandt, G., ' Ueber Scheitelzellwachstkuni bei den Phaneroganien,' 

 29 pp. (2 pis.). Graz, 1881. 



t SB. Dorpater Naturforsch.-Ges. Sept. 24, 1881. See Bot. Ztg., xL (1882) 

 p. 182. 



