544 LEGUMINOS 4. 
yields metagummic acid (Frémy) ; this is dissolved by solutions 
of the alkalies and alkaline earths with the reproduction of 
arabic acid. (Rhem. in Ding. Pol. Journ. 216, 539.) Gum even 
in small quantities injected into the blood diminishes the elimina- 
tion of urine; large doses completely stop the secretion, with a 
marked increase of blood pressure (Richet e¢ Montard-Martin 
Compt. Rend. 90, 88.) Gums yary much in the character of 
the solutions they yield, some give a thin syrupy solution, 
others a thick and jelly-like one; this is due to the varying 
proportion of the acid naturally converted into the meta modi- 
fication—the gums which yield the thinnest solution are those 
which contain the greatest amount of ash. Gums from the 
same source have not always the same optical activity. (Watt's 
Inet. of Ch. by Morley and Muir, ii., 296.) 
Susstirutes For Gum ACACIA. 
Weare indebted to Mr. J. G. Prebble of Bombay for the 
following :-— 
The exports of Indian gums for use as substitutes for gum 
arabic, have during the last few years obtained considerable 
proportions, and there is every probability of a steady increase 
due to the improvements in communication between the ports 
and the interior of the country, and the supplies promise to rival 
in the near future the large exports of gum from Senegambia. | 
The gums here described include the majority and the most — 
important of those known to be yielded by Indian trees; and 
most of them have been personally collected by the writer; 4 
few have been kindly forwarded by Mr. Duthie of Saharanpur 
and some by Mr. Cameron of the Lal Bagh, Bangalore. 
Nearly all the gums have been examined under the microscope, 
and in connection with this subject some account should 
perhaps be given of the recent interesting researches of Bei- 
jerinck and Wiesner. All gums were formerly supposed to be 
the dried mucilaginous sap secreted by a natural or physiolo~ 
_ gical process in the life of the plants yielding them. It was — 
first clearly shown by Mohl, that, in the case of tragacanth, — 
eae is = by a metamorphosis of the cell membrane pe 
