78 POLYGALE^. 



about as thick as itself. After the root has been macerated in water 

 -the bark is easily peeled off, and the peculiar structure of the wood can 

 then be studied. The latter immediately below the crown is a cylin- 

 drical cord, cleft however by numerous, fine, longitudinal fissure?. 

 Lower down these fissures increase in an irregular manner, causing a 

 very abnormal development of the wood. Transverse sections of a root 

 therefore differ greatly, the circular woody portion being either pene- 

 trated by clefts or wide notches, or one-half or even more is altogether 

 wanting, the space where wood should exist being in each case filled 

 up by uniform parenchymatous tissue. 



Senega root has a short brittle fracture, a peculiar rancid odour, ana 

 a very acrid and sourish taste. When handled it disperses in irritating 



Structure— The woody part is built up of dotted 



dust. 



A»l.l^.,l^Ja^^^Jpl«.; oi.rucxure- — me wooa}^ part is ounu up ^>- ""— 

 vessels surrounded by short porous ligneous cells ; the medullary rays 

 consist of one or two rows of the usual small cells. There is no pith m 

 the centre of the root. The clefts and notches are filled up with an 

 uniform tissue passing into the primary cortical tissue without a distinct 

 liber ; the large cells of this tissue are spirally striated. In the keel- 

 shaped rider the proper liber rays may be distinguished from the 

 medullary rays. The former are made up of a soft tissue, hence the 

 cortical part of the root breaks short together with the wood. 



Neither starch granules nor crystals of oxalate of calcium are present 

 in this root ; the chief contents of its tissue are albuminoid granule* 



and drops of fatty oil. 



Chemical Composition— The substance to which the dru^ o^^^ 

 its irritating taste was distinguished by the name of Senegin by UWcn 



Q 



tracted it 



as ih^PolygalicAcidf^ 



(1836) and of Procter (1859). Christophsohn (18/^) ^^j 



-„ .„ by means of boiling water, evaporated the solution an 



exhausted the residue with boiling alcohol (0-853 sp. gr.). The iiqu'^ 

 after a day or two, deposits the crude senegin, ^vhich is to be washe 

 with alcohol (0-818 sp. gr.), and again dissolved in water, from wliicn 

 is precipitated by a large excess of hydrate of baryum. The baryi' 

 conopound, dissolved in water, is decomposed by carbonic acid, by wmc^ 

 carbonate of baryum is separated, senegin remaining in solution. 1 

 lastly to be precipitated by alcohol. It is amorphous, insoluble in etii 

 and m cold water ; it forms with boiling water a frothing soluti^^ 

 Like saponin, to which it is very closely allied, it excites vioiei 



sneezinor. 



Dilute inorganic acids added to a warm solution of senegin thro 

 down a flocculent jelly of Sapogenin, the liquid retaining in solatw 

 uncrystallizable sugar. Alkalis give rise to the same decompositiji • 

 but it is difficult to split up the senegin completely, and hence the to 

 mulas given for this process are doubtful. Even the formula of sen^o , 

 Itself 13 not definitely settled. According to Christophsohn, the ro 



J7„ .{"^^V^ ? P^"" ^,^"1- 9^}'^^'^ substance ; according to earlier authoi^^ 



pure, a much larger proportion. ^^^ 

 ^..^..^.v.v.x o jLuvcfttigubiuns {iQio) it would appear that the rootlets 

 richest in senegin. 



Senega root contains a little volatile oil, traces of resin, also g"*' 



