MO /'///: 1//V//./.Y/.V.J/ or r/tr. c/Kcrr.ArroN. 



srtmuis. ly eaeh of wliirh the arterial pressure is driven up lo a great height. 1 

 This phenomenon surest s a elonie lit of the oiMitiv, the elomis of in- 

 voluntary niusele naturally taking pla<-e at a far slower rate than that of 

 skeletal nuiseles. 



l'u:. Si. 1 nj. M ion of absinthe. I'ur.iux^l tlo.;. 

 pivssuiv : ('. intranuiii.il pressure; P. 

 Hill. 



A. aortic I-I.-SMUV ; 1'.. vi-nn 

 vonous possuiv. 





lot or EneohAniam of tho veins. Tho portal venous 

 tin* thoracic jmrl.'i lo rhnnjn'J. tlu pri^ssuro in llu > rnrotul 

 arttM-y rises; if tlu> sphuu'hnir lUM-ves he then (\eiteil. the pressure in tho 

 enrol ill artery is raised to a still higher level. This full her rise is to he 

 attrihuteo! to t he ineroased diastolie tilling of the heart, \vhieh in its turn 

 is eausod hy the e\|>ulsion of the Mood from the portal system, an 

 expulsion \vhieh is hron^ht- ahoul hy eonstrietion of tln^ splanchnic 

 and hepatic vessels. After ligature of the portal vein, the s.une result 

 is ohtaincd. o\\ini: to eonstrietion of the ho|atie vessels.'-' 



l>.i\hss and Starling localise the outflow of vasoconstrictor nerves 

 to th^ portal system in from the third to the eleventh anterior thoracic 

 roots. \\\ excitation of the eighth to the eleventh roots, they ohtained, 

 lirst. a rise of pressure in the portal vein, due to eonstrietion of the 

 mescntcric arteries, forcing hlood on into the portal vein; secondly, a fall 

 due to the diminished flow of Mood through the mcsentoric arteries ; and. 

 lastly, a rise due to const net ion in tho hepatic hranohes of the portal vein/' 



the portal venous system is peculiar in its structural arrangement, 

 and generally hears a close analogy to an arterial vascular area. As to 

 the mnervation of the other veins \ve know very little. Thompson.' 

 after tyuiu r the crural artery and on excitation of the peripheral end 

 of tho divided sciatic nerve, has witnessed contraction of tho superficial 

 veins of the rahhit's lc^. lie has also witnessed the same in ahdominal 

 veins, on stimulation of tho peripheral end of tho divided cervical spinal 

 cord. The contraction is usually in tho form of hand-like constrictions. 

 hoi ween which the veins appear full of hlood. Such contractions appear 



' lv-\liss an.l Hill. ./oMfi% JtyW.. (\-ml>ii>l-^ ami London. lSt>.\ vol. \\iii. p. 850. 



r ,: . 1,M ,:.-,-. 1>".\ S 101). 



'/bum. MywW., r.-uutM-iil^ .-uul l.omlon. is i .M -i. i>. r:o, of. 



.nul M:in,M. ,rv ; , ; . . Tunn. IS'.);., vol. \\n. \>\\ 88, 296, 



>. s. KM, 



