APOCYNACEZ, 395 
yellowish brown colour, about 2 centimetres long and 2 to 8 
millimetres thick ; at one end of the seeds is a kind of shallow 
neck, to the sides of which was attached the tuft of hairs. 
One side of the seed is grooved, and in this groove may be - 
seen the raphé. Tho outer envelope of the seed is thin and 
papery, and within it is a thin white layer of albumen. The 
embryo consists of a conical radicle and two. foliaceous 
convoluted eotyledons. ae 
Microscopic structure—A section of the’ bark from the 
larger branches is remarkable for several layers of rhytidoma, 
the inner of which is in contact with the cambium; this struc- 
ture gives rise to exfoliations of portions of the outer layer 
of the bark. Simple and branched laticiferous vessels are 
to be seen, and a few groups of stony cells. The cells of the 
parenchyma are filled with starch granules and contain red 
colouring matter. Externally there isa thin layer of suber, 
In the young bark the rhytidoma is not a Tete conse- 
quently there is no exfoliation. 
Chemical composition.—The bark and seeds contain a ‘Basie 
substance (Wrightine), to prepare which the pulverised seeds: 
are treated with carbon bisulphide in a displacement apparatus _ 
_ to remove a fat oil, then dried and exhausted with hot alcohol ; 
the extract freed from alcohol by distillation, is digested with: 
a small quantity of dilute hydrochloric acid, and the evapora- 
ted filtrate is mixed with ammonia or sodic carbonate, . which: 
_ throws down a copious flocculent precipitate, consisting of the 
impure base. 
Wrightine after washing with cold water forms an: amor- 
phous powder, insoluble in ether and in carbonic disulphide, 
__ soluble in water and alcohol, and especially in dilute acids, 
: “with which it forms uncrystallisable salts having like the base 
itself a persistent bitter taste. The acetic acid solution is pre- 
cipitated by tannic acid; the hydrochloric-acid solution Bite : 
floceulent precipitates with platinic, auric, and mercuric ch!o- 
ides, (Stenhouse, Phar. Jour. (2) I ao a0), R. Haines (Ibid., 
VI, 432) states that he obtained the e same base fr e 
