FOLIA SENNiE. 219 



i 



incurled at the edges, conspicuously veined, the midrib being often 

 brown. They are covered with a very short and fine pubescence which 

 is most dense on the midrib. The leaves have a jDeculiar opaque, light 

 yellowish green hue, a somewhat agreeable tea-like, odour, and a 

 mucilaginous, not very marked taste, which however is sickly and 

 nauseous in a watery infusion. 



2. Arabian Moha, Bombay or East Indian Senna— This drug 



is derived from Cassia augustifolia, and is produced in Southern 

 Arabia. It is shipped from Moka, Aden and other Red Sea ports to 

 Bombay, and thence reaches Europe. ' 



Arabian senna is usually collected and dried without care, and is 

 mostly an inferior commodity, fetching in London sometimes as low a 

 price as |cZ. to Id. per lb. Yet so far as we have observed, it is never 

 adulterated, but consists wholly of senna leaflets, often brown and 

 decayed, mixed with flowers, pods, and stalks. The leaflets have the 

 form already described (p. 217); short adpressed hairs are often visible 

 on their under surface. 



3. Tmncvelly Senna — Derived from the same species as the last, 

 but from the plant cultivated in India, and in a state of far greater 

 luxuriance than it exhibits in the drier regions of Arabia where it 



grows wild. It is a very superior and carefully collected drug, consist- 

 ing wholly of the leaflets. These are lanceolate, 1 to 2 inches in length, 

 of a yellowish green on the upper side, of a duller tint on the under, 

 glabrous or thinly pubescent on the under side with short adpressed 

 hairs. The leaflets are less rigid in texture than those of Alex- 

 andrian senna, and have a tea-like, rather fragrant smell, with but 

 little taste. 



Tinnevelly senna has of late fallen off in size, and some importa- 

 tions in 1873 were not distinguishable from Arabian senna, except from 

 ny.ving been more carefully prepared. The drug is generally shipped 

 h-om Tuticorin in the extreme south of India. 



9^^"}^*^^! Composition— The analysis of senna with a view to 

 the isolation of its active principle has engaged the attention of nume- 

 rous chemists, but as yet the results of their labours are not quite 



satisfactory. 



Ludwig (1864) treated an alcoholic extract of senna with charcoal, 

 and obtained from the latter by means of boiling alcohot two bitter 

 principles, Sennacrol, soluble in ether, and Sennapicrin, not dissolved 

 l>y ether. 



•J^i'agendorff and Kubly (186G) have shown the active substance of 

 senna to be a colloid body, easily soluble in water but not in strong 

 alcohol. When a syrupy aqueous extract of senna is mixed wnth an 

 ^qual volume of alcohol, and the mucilage thus thrown down has been 

 rpoved, the addition of a further quantity of alcohol occasions the fall 

 in/ A^ brown, almost tasteless, easily alterable substance, which is 

 nuued with purgative properties. It was further shown that this 

 precipitate was a mixture of calcium and magnesium salts of phosphoric 

 a? 1 ?*^ ^ peculiar acid. The last named, separated by hydrochloric 

 tl?p ' ^^ ^^®^ c^^lcd Cathartic Acid; it is a black substance which m 

 ii^outh is at first insipid, but afterwards tastes acid and somewhat 



