ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 93 



a phenomenon which continues after the death of the plant ; (6) active 

 decomposition of albumen takes place in the ordinary atmosphere in the 

 dark, beginning even during the first 24 hours. 



•y. General. 



Parasites on Trees.* — Freiherr C. v, Tubeuf describes the diseases 

 produced in a number of trees by parasites, both phanerogamic and 

 cryptogamic. These include Botrytis Douglasii on Pseudotsuga Dou- 

 glasii ; Arceuihobium Douglasii and americanum on Pseudotsuga IJouglasii 

 and Pinus Murrayana ; the Japanese Loranthacese ; a new parasitic fungus 

 Trichosphseria parasitica on several conifers ; the witch-broom of Alnus 

 incana caused by Taphrina horealis ; Pestalozzia conorum Picese n. sp. ; 

 and the mycorhiza of Pinus Cenibra. 



Protection of Plants against Snails.j — Herr E. Stahl goes in great 

 detail into the means of protection exhibited by many plants against the 

 attacks of snails, whether land or fresh-water species. These may be 

 classed under two categories — substances contained within the cells, and 

 external morphological protection. 



Among the former may be named tannin, an acid cell-sap, especially 

 if due to calcium binoxalate, volatile oils, bitter substances, as in 

 Gentiana, Polygala, &c., and the oil-receptacles of some Hepaticee, &c. 



Among external protections are stiff hairs, impregnation of the 

 epiderm with lime or silica, and the formation of mucilage or jelly (this 

 applies especially to water-plants). Eaphides also protect plants, both 

 by their poisonous properties, and by the injury inflicted by the sharp 

 crystals on the internal organs of animals ; some animals, however, such 

 as the caterpillars of Deilephila, consume greedily plants which contain 

 raphides. 



B. CBYPTOGAMIA. 



Cryptogamia Vascularia. 



Chlorophyll-bodies of Selaginella.J — Herr G. Haberlandt describes 

 the structure of the chlorophyll-bodies in several species of Selaginella. 



In the cells which are specially connected with assimilation in many 

 species of Selaginella, there is only a single chlorophyll-body, resembling 

 the similar arrangement in Anthoceros, and this has frequently somewhat 

 of a cup-form ; but in its finer structure it agrees completely with the 

 chloroplasts of the higher plants, showing distinct granulation. In the 

 cells of the base of the leaf there is usually either one irregularly lobed 

 chlorophyll-body, or several of different forms. In the parenchymatous 

 cells of the cortex of the stem are a number of chloroplasts, usually more 

 or less of a spindle-form. They are united together by delicate colour- 

 less strings of protoplasm forming a continuous branched or unbranched 

 chain in each cell. The substance of these chains does not belong to 

 the cytoplasm, but to the chlorophyll-bodies. Some of the chloroplasts 

 in these chains are usually transformed into leucoplasts. The stai'ch in 

 them occurs in the form of either minute grains or rods. 



As regards their history of development, Haberlandt finds even in 



* ' Beitr. z. Kenntniss d. Baumkrankheiten,' Berlin, 1888, 58 pp. See Bot Zto-., 

 xlvi. (188S) p. 659. 



t Jenaische Zeitschr. f. Naturw., xxii. (1888) 126 pp. See Bot. Centralbl , 

 xxxvi. (1888) p. 164. J Flora, Ixxi. (1888) pp. 221-308 (1 pL). 



