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XXXVI. The EffeEls of the Opuntia, or 
Prickly Pear , and of the Indigo Plants 
in colouring the Juices of living Animals . 
Communicated by H. Baker, F. R. S. 
June 23d, 1757. 
Read June 23, 'll /TR. Baker received a letter yefterday 
from Dr. Alexander Garden, of 
Charles Town in South Carolina, part of which he 
hopes he fhall be excufed for laying before the Royal 
Society. 
The Doftor writes thus : <c As you defired, I 
“ tried the effedts of the prickly pear in colouring 
“ the urine. A few days after your letter, I went 
“ down to one of the iflands, and gathered fome of 
“ the fruit, and gave four of the pears to a child of 
<{ three years of age, and fix pears to one of five. 
tc The next morning I examined the urine of both, 
“ and it appeared of a very lively red colour, as if 
<c tent-wine had been mixed with clear water. The 
“ urine of the eldefi: was deeper coloured, and of a 
“ darker look: the youngefl (who always naturally 
“ made clear urine) was of a more lively and beau- 
“ tiful red. Next day I gave fix pears to a Negroe 
“ wench, who gave fuck, and ftridtly forbad her 
“ fuckling her child for fix or eight hours ; and 
4t then taking fome of her milk in a tea-cup, and 
“ fetting it by for fome hours, the cream had a red- 
“ difh luftre, tho’ it was very faint. 
“ I was led to this lafi: experiment by an obferva- 
“ tion, which I made on the milk of cows, who 
“ had 
