174 ELEMENTAKY PHYSIOLOGY. [XVI. 



(parapeptone) will be obtained (cp. Less. IX. 15). 

 Filter off the acid-albumin, the filtrate contains 

 peptones. 



5. Determine the following characters of peptones 

 with the solution obtained in 4. 



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

 Millon's and the xanthoproteic reaction are 

 obtained, but no precipitate is produced with 

 acetic acid and potassium ferrocyanide. 



b. Boil ; it does not coagulate. 



c. Add excess of sodium hydrate and a drop or 

 two of dilute cupric sulphate, a rose 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 in. 16 c). 



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

 peptone and into another (5) diluted serum 

 or white of egg. 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 fat globules of varying size. Add a 



