CHEMICAL BASIS OF THK ANIMAL BUl>Y. 



con.-ideivd tin-in to be identical, 1 but that they are m-t M U -ntti- 

 ciently -hewn by th.- following facts. Solutions of alkali-albumin 

 In- made to clot by the action of pure rennjn. If milk 



In- added to tin- solution and impure rennet,] e. extract of 

 tin- niuc.ui> membrane containing rennin, be allowed to act upon 

 it, in -onie cases a separation of the alkali-albumin may take 

 place, owin^' to the formation of lactic acid which then preeipi- 



the allnimin. In the absence of the milk -n-_ r ar n> change 

 i- produced which can in any way be regarded as analogous t 

 the dotting i if casein. When milk is clotted the se]>aratiun uf the 

 casein is so complete that none is found in the ' whey.' and Ham 

 marsten has shewn that if alkali-albumin be added to milk and 

 the mixture be then clotted, alkali-albumin may be obtained fnmi 

 the whev on breaking up the curd, It has further been shewn - 

 that although casein i- \ei\ resistant to the action of acids, it 

 may by treatment with them be converted into acid-albumin w i 1 1 1 

 complete loss of all clotting powers, ami still more readily into 

 alkali-albumin by the action of alkalis. 



A farther difference of tin- t\\.> sultances was urged l.\ /aim <>n 



tin- ba>is i.i hi> e.\]H-riineiit> MH tin- till rat i ...... l' milk tln-Mii^h |IMI-MUS 



eartheiiNvare (liattery-cells). 8 He I'mmd that scilutions of ulkali-allm 

 min ]>a thi'Dii^h the \\alU \ the relU as rapidly a> <1" -.>luti-ii> !" 

 M-riim-albiimin . \\Iim milk Imwever is filtered hy tlii- nietlnnl. . 

 il-ie- nut |>a^-. and the liltrati- fi.n>i>t> "i' \\ater. .-alt^. and the i-na^nla- 

 l>le pi-Mteid uf the milk. Whether thi> mdi-ate> any difference be- 



t\\ecll the t\\M >||li>talice> i> Il<>\\eVer d< Mlht t'll 1. 1"1' it ! .-till all n|.fll 



<|iiestiMii whether ea-ein is truly in .sMlntimi in milk. Furtlier it i> 

 >tated that tin- ra>ein al>M pa .-. int.. the filtrate it" the liltrati. >n is 

 ).r..l..n^ed. 4 and S, .xhlet >tat.- that if lim-ly di\ nleil (i-mulsified) fat 

 -peiided in a >..lnti..n <.f alkali-albumin the filtrati..n of tin- -nl>- 

 >tanee is rendered as inip..--il'l>' a- that <>\ ca-i-in in milk. 



The crucial distinction between the two substances is the fact 

 t hat casein can be clotted by reiinin with simultaneous format ioi i 

 of a soluble ]iroteid by-|jrodiict. whereas^io true clot can ever k' 

 i >l ttained from ordinary alkiili-i'lbiiiuin 



r Uu- removal of"casc'in from milk by j.iv. ipitati<m. th 



[i It rate contains a small amount of coagulablu ])rui>-iil. 



sj)oken of as 'laetalbninin,' closely resembliiiLj serum-albumin in 



eneral properties, but dilleriim slightly as t.. n 

 .]> power and th- tempeiat UP- .n which it ...adulates when 

 heated. 6 



tit. 



tiil!.TU, lor. nt. 

 /., -.-.. I": -.-r* Arch. H.I. u -.98. 



',. /. ,/ mea I ?* 



ft Sell-li.-!. . Mil- OM>1. S 



1885), S. IW. Hallil.urt.m. .// tfPkg**, Vol XI. 



