IX.] PROPERTIES OF CONTRACTILE TISSUE. 103 



obtained like that of syntonin ; if too much acid 

 is added the precipitate will be converted into 

 acid-albumin and re-dissolved. Take in separate 

 test-tubes a little of the precipitate suspended in 

 water. 



a. Add a little NaHO '1 p.c. the precipitate at 

 once dissolves and is not precipitated by 

 boiling ; with the proteid tests a reaction is 

 obtained. 



Z. Boil, cool under a tap and add a little NaHO 

 1 p. c., the precipitate suspended in water has 

 been coagulated by boiling and is no longer 

 soluble in dilute alkalies. 



c. Add a little NaHO '1 p.c. and a little sodium 



phosphate, with a drop of litmus solution; add 



drop by drop dilute HC1 : on neutralizing no 



precipitate takes place, add a little more 



acid a precipitate is obtained, if still more is 



added the precipitate is re-dissolved. 



It will have been seen that proteids in solution 



(except peptone) on warming with dilute acids 



or alkalies give rise to acid albumin or alkali 



albuminate respectively, these substances do not 



coagulate on boiling and so differ from albumin 



and globulin, and are insoluble in water and so 



differ from peptone (cp. Less. XVI. C. 5). 



DEMONSTRATIONS. 



1. The electric currents of resting muscle removed 

 from the body (demarcation currents) 



