ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 83 



a plant partially illuminated it is present, though in smaller quantities 

 than in a plant cultivated entirely in the light. The carbohydrates 

 elaborated in the leaves exposed to light may accumulate in the parts 

 ■of the plant which are not directly exposed to light. 



Influence of the different Solar Rays on the Form and Structure 

 •of Plants.* — M. E. C. Teodoresco gives a review of the literature of this 

 subject, and of the general conclusions that can be drawn iu the present 

 state of our knowledge. He then recounts the results of his own obser- 

 vations made in two different ways, by the use of coloured screens and 

 by the spectroscope. With regard to the leaf, he finds the various 

 coloured rays less favourable to their development than total light. The 

 palisade- and air-tissues have a minimum development in the green ; 

 more in the red ; most in the blue. The chloroleucites are smallest 

 and least numerous in the green ; the stomates are more numerous in 

 the green than in the red, and in the red than in the blue. The results 

 obtained in the root and in the stem confirmed the general conclusion 

 that green light is least favourable to the development of the plant ; the 

 maximum development of all the tissues being, on the other hand, most 

 promoted by the most refrangible ravs of the spectrum, viz. the blue and 

 the indigo. 



Influence of Electricity on Plants.-f — Herr H. Euler gives the 

 result- of previous investigations on this subject, and of his own obser- 

 vations, chiefly on Elodea canadensis. He states that the electrical 

 processes in the atmosphere can only slightly change the amount of 

 dissolved gases in water which does not contain bacteria. Atmospheric 

 electricity can therefore have no direct action on the growth of plants 

 or of the parts of plants in water or in damp places. 



Grafting of Monocotyledons on themselves.} — M. L. Daniel has 

 been attempting for a long period the hitherto unsolved problem of 

 ■^rafting a Monocotyledon on itself, and with a large amount of success 

 in the cases of a species of Vanilla and a species of Philodendron. The 

 grafts are of the nature previously termed by the author "mixed 

 grafts." 



Germination of Seeds. § — From a long series of experiments on the 

 germinative power of the seeds of a large number of American plants, 

 mostly belonging to the order Compositae, Prof. Stanley Coulter has 

 arrived at the following general conclusions. The germinative per- 

 centage in the Compositae is smaller than in the other families examined. 

 In most cases the achenes show the highest germinating percentage if 

 collected at about the middle of the flowering season. For the most 

 part the central achenes of the head are not viable, and the same con- 

 dition is frequently found in the outer rows. The seeds of all species 

 of Compositae studied were found to be particularly sensitive to changes 

 in temperature and moisture. Cotyledons of nearly related species 

 closely resemble each other, a resemblance often carried on to the 



* Ann. Sci. Nat. (Bot.), x. (1899) pp. 141-263 (4 pis. and 18 figs.), 

 t Ofv. k. Vetensk. Akad. Forhandl., lvi. (1899) pp. 609-30 (1 fig.) (German). 

 t Comptes Rendus, cxxix. (1899) pp. 654-6. Cf. this Journal, 1898, p. 101. 

 § Proc. Indiana Acad. Sci., 1898, pp. 215-22. 



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