174 ELEMENTAET PHYSIOLOGY. [XVI. 



(parapeptone) will be obtained (cp. Less. ix. § 15). 

 Filter off the aeid-albumin, the filtrate contains 

 peptones. 



5. Determine the following characters of peptones 

 with the soliition obtained in § 4. 



a. Apply the tests for proteids (Lesson iii. § 16), 

 Millon's and the xanthoproteic reaction are 

 obtained, but no precipitate is produced with 

 acetic acid and potassium ferrocyanide. 



h. Boil ; it does not coagulate. 



c. Add excess of sodium hydrate and a drop or 

 two of dilute cupric sulphate, a rdse colour is 

 produced which becomes violet when more 

 cupric sulphate is added. Compare the 

 colour reaction with that given by diluted 

 serum or white of egg (Lesson III. § 16 c). 



d. Pour into one dialyser {A) a solution of 

 peptone and into another {E) diluted serum 

 or white of Qgg. Leave for an hour or 

 longer, then apply the xanthoproteic test to 

 the fluid outside the dialyser, a reaction will 

 be obtained from {A) only, i.e. the peptone 

 has dialysed, the albumin has not. 



D. Milk. 



1. Examine a drop of fresh cow's milk under the 

 microscope with a high power. It consists of a 

 clear fluid containing a large number of highly 

 refractive faA globules of varying size. Add a 



