ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 547 



which were watered with tap-water. Sodium fluoride acted as a stimulus 

 to pea-seedlings in water-culture ; the optimum concentration lies be- 

 tween 0-0021 and 0*00021 p.c. A concentration of 0'02 p.c. had a 

 poisonous effect. 



Chemical Changes. 



Occurrence of Invertase in Plants.* — J. H. Kastle and Mary 

 E. Clark have examined nineteen species representing fourteen families of 

 plants, and find invertase abundantly in each and more constant in its 

 occurrence than diastase. Contrary to the views of Bechamp, it occurs 

 abundantly in the leaves ; it also occurs in some rather unexpected 

 associations — for instance, in the growing tubers of the potato and arti- 

 choke, where we should be inclined to expect the occurrence of relatively 

 large amounts of inulase and diastase respectively, these ferments are 

 present but in less quantity than invertase. It is of interest to note 

 that invertase is not confined to those plants which store cane-sugar as 

 the characteristic reserve material. The fact that it occurs so generally 

 in foliage leaves, and is so widely disseminated throughout the various 

 plant organs, lends support to the view of Brown and Morris that cane- 

 sugar is the first product of photosynthesis, and the fact that it is also 

 present in the reserve organs of plants storing inulin as well as those 

 storing starch would seem to point to cane-sugar as the substance 

 immediately antecedent not only to starch but to other reserve materials. 



Zymase and Alcoholic Fermentation. f — P. Maze continues his 

 researches on this subject. The production of the zymase has hitherto 

 been considered as limited to a larger or smaller number of living cells, 

 and forming generally a kind of anomaly. The author has shown that 

 the conversion of sugar into alcohol and C0 2 is very general in living 

 cells under normal conditions. Zymase is a diastase formed in aerobic 

 conditions, and its action on sugar must be regarded as a phenomenon 

 of digestion. Hence the alcoholic fermentation in absence of oxygen so 

 often observed in plant and animal tissues, must be regarded as the 

 continuation of a diastatic action which has its origin in normal life. 

 The general poverty in zymase of plant and animal cells is due to its 

 rapid destruction, probably by an oxidation process. 



General. 



Botany of Belle Isle.* — Emile Gadeceau gives an exhaustive account 

 of the botany of this small Breton island. After a general account of 

 the topography, climate, geology and cultivation, he gives a catalogue 

 of the vascular plants found on the island, with notes on their habitat. 

 The third part of his paper is devoted to plant-geography or cacology ; 

 here the author discusses the influence of climate, of soil, etc., on the 

 distribution of the plants, and describes the various plant-associations. 

 Finally he tabulates the following general conclusions. Climate exer- 

 cises a strikingly preponderant influence on the dispersion of species, 



* American Chem. Journ., xxx. (1903) pp. 422-7. 

 t Comptes Rendus, cxxxviii. (1901) pp. 1514-17. 



X Mem. Soc. Sci. Nat. & Math. Cherbourg, xxxiii. (1903) pp. 177-368 (3 pis. and 

 map). 



