ZOOLOGY AND BOTANY, MICKOSCOPYj ETC. 389 



called the transpiratory reserve, it might be better to term the vas- 

 cular transpiratory reserve. I propose to publish a work on vrater 

 reservoirs in general. A study of this apparatus very often gives the 

 key as to the resistance of certain plants to certain surroundings, and 

 permits us to indicate at once the conditions under which we must 

 cultivate plants. Anatomy, I am convinced, will open the way to 

 rational culture." 



Permeability of Wood to Water.* — Examination of the structure 

 of the wood in a number of gymnospermous and angiospermous trees 

 and shrubs has led F. Elfving to the conclusion that the wood loses its 

 permeability for water as soon as the cell-cavities become completely 

 closed. The water of transpiration cannot therefore be conducted 

 through the cell-walls, but filters from cell to cell. In the tracheides 

 of the Conifers it is clear that the largest part of the cell-wall serves 

 as a support for the separate tracheides ; while the filtration can take 

 place only at definite spots, viz. the bordered pits. 



Trichomatic Origin and Formation of some Cystoliths. t — 

 J. Chareyre saw in a very young leaf of Morus alba that the hairs, 

 which were very long and a little swollen at their base, were gradually 

 filled with a striated mass incrusted by calcareous matter. With age 

 these hairs become absorbed, their extremity undergoing atrophy, and 

 their lower portion swelling and becoming globular. The cystolithic 

 mass became detached from their walls, and, in the adult leaves, the 

 extremity of the hair disappearing entirely, the basal portion, now 

 inclosed in epidermis, formed a true cystolithic cell. We here, 

 then, have cystoliths which are of epidermal origin and are most 

 frequently developed at the expense of a hair, though in rarer cases 

 from the outer wall of an epidermal cell. There is another category, 

 examples of which are to be found in some Acanthacese and Procrideae, 

 in which the cystoliths exist in all the tissues, and are developed 

 at the expense of the cell which contains them. The two categories 

 may perhaps be connected together by the linear cystoliths of some 

 Ortige. 



Formation of Starch out of Sugar.J — J. Boehm contests the 

 ordinary view that the starch formed in chlorophyll-grains is a direct 

 result of the decomposition of carbon dioxide ; he believes it to be in 

 many cases formed out of other organic substances, especially sugar, 

 which have found their way into the chlorophyll-grains. Starch is in 

 this way often formed in the absence of light in grains of chlorophyll 

 or of etiolin. In order to confirm this hypothesis, leaves and pieces 

 of the stem of the scarlet-runner, containing no starch, were exposed 

 to the action of a solution of sugar, when they were found, after twenty- 

 four hours, to contain abundance of starch ; the quantity depending 

 on the concentration of the solution of sugar ; the temperature, 

 between the limits of 10° and 20° C, appearing to make no difierence. 

 In leaves of Galanthus, Hyacinthus, Iris, &c., starch was produced in 



* Bot. Ztg., xl. (1882) pp. 707-23. 



t Comptes Kendus, xcvi. (1883) pp. 1073-5. 



X Bot. Ztg., xli, (1883) pp. 38-8, 49-54. 



