CHEMICAL BASIS OF THK ANIMAL linDY. 25 



by cow's milk. (3) Th_e <"isein in human milk is, as already 

 stated, very incompletely precipitated by the addition of acids. 

 and can only be completely precipitated by saturation with imiL f - 

 nesium sulphate. 1 (4) Casein irom hitman milk is less solu hie 

 in water than is that of the cow. 



The primary di;r>tivr prodm" l>tain-d hy the action 



of pepsin on casein have hern dr-eril>rd and studiril l.y Chittrndrii 

 and Pain' 



CLASS III. GM'tilhiii. 



Besides the derived alhimiins there are a nuinher of native 

 j^nbjjds which (litter from tin. 1 alhuinins in not heinij soluije in 

 distilled waiter ; they need for their solution tjje presence <>f ;in 

 uh it ma 



appj-ecjahle. t liou^h it may be a small, quantity of a neutral saline 



suhstaiier such as sodium chloride. ThusTTiev reseinhle the alhu- 

 iniiiates in not hein^ soluhle _m distilletl \vajj-r. hut djjler from 

 thc'in in heiiiLj soluhle in dilute'^'dium chloride or other neutral 

 saline solution.-/' Their~u r ''iieral characters may he stated as follows. 

 They are insoluhle in water, soluhle in dilute ( 1 j.r.) solutions 

 lium chloride; they are also sojiibje in dilute neids and 

 alkalis, Itein^ changed on solution into acid- and alkali-alhumin 

 respectively unless the acids and alkalis are exceedingly dilute 

 and their action is not prolonged. The saturation with solid 

 sodium chloride or other neutral salts of their Miline solutions 

 1'ivcij.itates most members of this class. 



1. Crystallin. (Globulin of tk eryttoUii 



This form of ^lohulin is usually regarded as identical^ with 

 vitt-TTiii. Tt is howev.'r convenient to treat it separately, inasmuch 



;|s ij_eall I'" pivpaivd jj, a | Hi 1 e forill. whel'eas \Jtellill lias IlOt as 

 ohtailied t'lvi ^tVolll lecithin (see I.eloW). 



/ . /t,->it<ii* Crystalline leii^-s. in which it occurs to the 

 i of L 1 1 -t'.'J p.p.. are rnhheil up in a mortar with a little fine 

 sand and a few civ-tal- !' IM, k -alt : the n. 'iien e\tr 



with water and tiltered. The liJtrate .ontains the crvsfallin and 

 some -eruin-alhiiiiiiii. Thelornier is separated from the laf 

 copious dilution with distilled water and a current ot 



carlionie anhv.lride thmu-jh the diluted mixtir upon the 



:allin is precipitated. 

 A diluto dine solution of this j.n.t. -id OOftgulattt at 75. 



Makria. ln> I'-' rt. (II 



,ijol. <V..) -'156. 



\ik..ljnkin (l;u-M:u.). Al.st in M 

 4 Uptwliinskv, I'll..-, r - I 15,1. MM (I- 



