MILK-PRODUCING PLANTS. 
51 
and hydrocyanic acid.* These mixtures vary not only in 
the different families, but also in the species which belong 
to the same genus. Sometimes it is morphine or the nar- 
cotic principle, that characterises the vegetable milk, as in 
some papaverous plants ; sometimes it is caoutchouc, as in 
the hevea and the castilloa ; sometimes albumen and easeum, 
as m the cow-tree. 
Ihe lactescent plants belong chiefly to the three families 
ot the euphorbiacese, the urticese, and the apocinetct- Since, 
on examining the distribution of vegetable forms over the 
g o e, we find that those three families are more nume- 
I??? 11 s i )eci , es , m the low regions of the tropics, we must 
i , e , conc lude that a very elevated temperature contri- 
Cal) ?f ltl0u of tho milky juices, to the formation 
albumen, and caseous matter. The sap of 
de ? aca ^mshes unquestionably the most striking 
example of a vegetable milk m which the acrid and de- 
not llrlited ™th albumen, easeum, 
ever a euphorbia and asclepias, how- 
ever though generally known for their caustic properties 
already present us with a few species, the juice oi P which 
Cam™ tT* r rm .°- S t S,,ch are *be Tabayba dulce of the 
anary Islands, which we have already mentioned,! and the 
Asclepias kctifera of Ceylon. BurmV relates that, in the 
latter country, when cow s milk is wanting, the milk of this 
nfTV* U - S6d 1 ; aud tbat tlie Aments commonly vve- 
paitd with annual milk are boiled with its lenvps if 
be possible, as Deed* bss wdl iisemd ftot £ 
natives employ only the juice tbst Sow, fi™, the “ouuJ 
piant, at a period when the acrid principle is not yet‘deve & 
eSn inleve*! %&**' «*• *»"*— • ™ 
+ ?S iu “. C0B ^“ ns “OfpWne, caoutchouc, &e. 
racese the inhcU * am ’^ 8s fo 'l° w the papaveracese, the chico- 
tacese.’ Th , b ? aCei8 ’ , the “mpanulacese, the sapotes;, and the cucurbi- 
dalacese Tn fh c ^ amc acl ^ J s peculiar to the group of rosaceo-amyg- 
the peris, Jm of monocotyledonous plants there is no milky juice; but 
emulsions contai^ pal “ s >, whlch y le lds such sweet and agreeable milky 
mushrooms? 1 ’ doubt> caseum ' 0f what “Cure ia the milk of 
+ Euphorbia balsamifcra. 
equally sweet. 
The milky juice of the Cactus maraillaris Lr 
E 2 
