234 BOMBAY NATURAL HISTORY SOCIETY» 
use mango or limes to remove the acidity. They have found by 
experience that kokum and tamarinds will not answer for this 
purpose. I find by experiment that calcic oxalate is soluble ina solu- 
tion of citrates but not in a solution of tartrates and malates, to 
which the acidity of tamarinds and kokumisdue. Schima Wallichii, 
a tree of Nepal belonging to the Ternstreemiaces, affords us an 
excellent example of a very starchy bark protected from the attacks 
of animals by a peculiar development of the liber, which resembles 
sharp glistening white needles, and causes much irritation when 
handled, The Nepalese call the tree chilawnt, or itch tree, and 
makkarchal, or spider’s itch tree. The liber cells are about +5 
of an inch long, translucent, and sharp-pointed at both ends; the 
bulk of the parenchyma consists of cells containing starch and a 
red colouring matter; by macerating the bark with water, the liber 
cells are easily separated and may then be examined under the 
miscroscope. 
The bulbous roots of squillsand many of the Liliacew are protected 
by the presence of irritating raphides, the effects of which are well- 
known to those who have to slice these bulbs preparatory to drying 
them for medicinal use. The raphides, like those of the aroids, 
consist of calcic oxalate deposited in cells containing mucilage and 
forming bundles of necdle-shaped crystals or large solitary square 
prisms. Oxalate of calcium is generally associated with mucilage 
in most plants, and this fact is remarkably evident in the squill and 
other lily bulbs. If these bulbs are finely sliced and shaken in a 
bottle with water, a quantity of the crystals will be deposited, and 
are clearly visible to the naked eye, but it must not be supposed 
that every plant which contains calcic oxalate has acrid properties. 
This depends entirely upon the shape of the crystals, of which 
thirty-four forms at least have been observed iu European plants. 
Ina recent number of the Dutch journal, Maandblad voor Natwur- 
wetenschapen, J. H. Wekker, in an article upon “De vorming 
der kristallen von oxalzure kalk in de plantencel, ”’ shows, that 
even in the youngest cells the crystals are always found in the 
vacuole, and if the microscope be inclined, they will show by gra- 
vitation that they are free and not embedded in the protoplasm. 
Wekker found this to be the case in twenty-nine different plants 
examined by him, only occasionally a crystal adheres to the proto- 
plasm bordering the vacuole and is set in motion by it. These 
observations explain the rapidity with which the irritating effects of 
