366 NATURAL SCIENCE. June, 



More than twenty years ago Boehm came to the conclusion that 

 one of the functions of calcium was to assist the carrying of carbo- 

 hydrates. Working subsequently on the same subject, A. F. W. 

 Schimper showed that, in plants which normally contain crystals of 

 calcic oxalate, oxalic acid is a bye-product in the building up of 

 proteids, and that, in the absence of calcium, acid potassic oxalate 

 accumulates in the leaves and buds and acts as a poison. He con- 

 cluded that the calcium served to neutralise this salt, but played no 

 fundamental part in the conduction of carbohydrates, since these 

 were proved to travel without a corresponding movement of calcium. 



Groom suggests that the choking of the tissues with starch may 

 be due to the fact that potassic oxalate arrests the change of starch 

 into sugar, and shows by experiment that the diastatic action of 

 extract of malt upon arrowroot-starch is hindered by even very dilute 

 solutions of the acid salt ; also that the same substance retards the 

 process of the change of starch into sugar in the living leaf of the 

 Canadian water-weed (Elodea canadensis) ; and further, as the soluble 

 oxalate accumulates, that the manufacture of starch is retarded, and, 

 finally, the protoplasm is killed. The possibility of the diastatic 

 action in plants, which, like Oxalis, normally contain a considerable 

 amount of acid potassic oxalate in solution in their leaves, is explained 

 by the fact already elucidated by Giessler, that the salt is stored in 

 the epidermis, not in the assimilating tissue. Giessler suggested that 

 the object was protection from snails and the like, but Groom thinks, 

 from his own experiments, that the protective significance is at most 

 secondary, and that the primary reason of the superficial storage of 

 the oxalate is because its presence in the underlying tissues would 

 derange the metabolic processes. 



The Flora of the Soondreebun. 

 The issue of the Proceedings of the Linnean Society (from November, 

 1894, to June, 1895), which has recently appeared, includes an 

 interesting presidential address by Mr. C. B. Clarke on the Soondree- 

 bun of Bengal. This contains not only an account of the flora of the 

 district, but also notes on its geography and natural phenomena. 

 The derivation of' the name is a much disputed point ; Mr. Clarke 

 adopts the one which gives the word as Soondree-bun, meaning the 

 forest of " Soondree," or Heritiera Fomes, a prevalent tree in the salt- 

 water swamp-forests of the mouths of the Ganges, and important 

 from an economic point of view. The area included is about 8,000 

 square miles, and by no means uniform in character. There are 

 large tracts of mud flooded at high water, but becoming hardened in 

 the sun at low tide, when it is possible to walk for several hours 

 among the scattered and open mangrove vegetation. There are also 

 large open areas of grass, and, thirdly, the Soondreebun proper, with 

 dense jungles of Soondree on tolerably firm mud, broken in all 

 directions by creeks. The grass jungles are full of beasts ; the tiger, 



