EXPERIMENTS ON LIVING CINCHONA. 
7 
These analyses lead to some conclusions of importance. The alkaloid first found in 
the freshly forming tissues is quinine, although the tree is of a kind producing mainly 
cinchonidine. As first formed, however, the quinine refuses to form crystalline sulphates ; 
it is “ uncrystallizable quinine.” After two months more growth a third part of this 
quinine has obtained the ability to form crystallizable salts, and a small amount of cin- 
chonidine and cinchonine are formed, both of which are recognized by their crystalline 
form under the microscope. These latter constantly increase ; and in the above and 
other similar experiments the increase seems made at the expense of the crystallizable 
quinine, which simultaneously diminishes. The order of formation in point of time is 
thus shown to be, 1st, uncrystallizable quinine; 2nd, crystallizable quinine ; 3rd, cin- 
chonidine and cinchonine. 
Furthermore, the very local character of these peculiar changes seems to render it 
highly probable that the alkaloids are really formed in situ in the very tissues in which 
they are found, — that is, the very cells which contain them also have formed them. It 
has been shown above how very minute an amount of alkaloids the leaves, wood, and 
twigs contain. The quinine in the leaves, small though it be, forms a crystalline sul- 
phate. The alkaloid that is found in the freshly forming bark refuses to crystallize ; it 
is therefore scarcely credible that it owes its origin to the distant leaves (according to the 
prevalent notion that all the plant principles are formed therein). If this could be con- 
ceived to be the case, it would at least be expected that the crystalline principles would 
appear first. Also for seventeen months after its formation the newly made bark is found 
to differ in composition from the rest of the bark of the tree by containing much quinine 
and little cinchonidine, precisely the reverse to what is contained in the older portions. 
The conclusion thus appears to be inevitable that the alkaloids are formed in situ. I 
find that Mr. Howard* on other grounds also inclines to the same conclusion. 
The opinions as to the actual seat of the alkaloids in cinchona-bark have been divided. 
Waddell, Wigand, and others have stated on deductive grounds that they are mainly 
contained in the liber ; Howard, on the other hand, by several direct experiments made 
with various South-American barks, found the largest amount in the external cellular 
portions (‘Nuova Quinologia’ of Pavon, Appendix). By adopting Howard’s method 
of actually separating the liber, and making an analysis both of it and the remaining 
cellular portion, I was enabled abundantly to corroborate his results. The following 
analyses illustrate mine : — 
1st Series. 
2nd Series. 
Liber. 
Cellular 
portion. 
Liber. 
Cellular 
portion. 
Total alkaloids 
5-94 
7-98 
6-85 
8-00 
Quinine 
0-70 
2-25 
O'So 
3-25 
Cinchonidine and cinchonine ... 
5-24 
5-74 
6-00 
4*75 
Sulphate quinine obtained 
0-90 
2-80 
Sulphate cinchonidine obtained... 
4-10 
4-20 
* Quinology of the East-Indian Plantations, p. 16. 
