ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 515 



plant. Further, the collodion film can usually be stripped off with ease 

 and examined under the Microscope, and inter alia it affords a trans- 

 parent and perfect cast of the epidermal cells, stoma ta, &c. And as 

 solutions, such as cobalt chloride, can be added to the collodion solution, 

 the moisture of transpiration can also be made to yield colour-reactions. 

 The authors publish the results they have obtained in connection with 

 cuticular and stomatic transpiration, the influence of light and of me- 

 chanical strain on the stomatic cells, the influence of drought and of 

 chemical vapours (ether, &c.) on transpiration, the structure of organs 

 of movement and of parts in course of growth, the behaviour of lenticels 

 and hydatodes. A long bibliography is appended. 



Function of Calcium Oxalate in Plant Nutrition.* — M. Amar, 

 working with various genera of Caryophyllaceas, finds that the deposits 

 of calcium oxalate crystals become less in quantity as the distance from 

 the blade of the leaf increases, in following the course of the elaborated 

 sap. This suggests that the crystals are formed at the expense of this 

 sap, and are deposited chiefly immediately after its elaboration, in the 

 cells near the assimilating and conducting tissues. The author also 

 shows that when once laid down the crystals remain and are not used 

 up when the plants are removed from the soil and grown in a culture 

 solution which contains no calcium compound ; that is to say, the calcium 

 oxalate is merely a product of excretion. By germinating seeds in a 

 similar culture solution seedlings with four or five pairs of leaves were 

 obtained which contained no calcium oxala?3. 



Periodicity of Morphological Phenomena in Plants.f — Under this 

 title Tine Tammes describes a number of observations on the influence 

 exerted by the presence or absence of leaves on the period of growth in 

 length of the intemodes, and the presence or absence of leaflets in the 

 growth in length of the intervening portions of the leaf-rhachis. He 

 has also studied the relation of variation or periodicity in certain 

 characters of the leaf and leaflet to the same phenomenon. 



Irritability. 



Stomata of Cotyledons.^ — GL B. Traverso has tabulated the results 

 of his observations on the influence of light upon the development of 

 stomata in cotyledons, and deduces the conclusions that the number of 

 both stomata and ordinary cells formed per unit of surface in cotyledons 

 grown in darkness is greater than in those grown in light. But the 

 proportion of stomata to ordinary cells in cotyledons grown in darkness 

 is less than in those grown in light, because in darkness the ordinary 

 cells are multiplied at a greater rate than the stomata. In other words, 

 the percentage of stomata is greater in light than in darkness, though 

 the actual number is less per unit of surface. 



Statolith Theory of Geotropism.§ — F. Darwin describes experi- 

 ments made by himself which are confirmatory of this theory, which 



* Comptes Kendus, cxxxvi. (1903) pp. 901-2. 



t Verhandl. Kon. Akad. Wetensch. Amsterdam, Sect. 2, Deel ix. No. 5 (1903) 

 pp. iv., 148 (1 pi.). 



% Atti d. IstiL. Bot. Univ. Pavia, vii. (1902) pp. 55-64. 



§ Proc. Roy. Soc. lxxi. (1903) pp. 362-73. See also Nature, lxvii. (1903) pp. 571-2. 



