X. THE CHANGE OF PROTOPLASM STRUCTURE 



299 



though such a phenomenon was rather rarely observed, in most cases 

 only regular progresses being seen. 



^ lOOr 



j 5 10 15 



— ► time (minutes) 



Fig. 27. 

 Decreasing progress of the rennet action due to tannic acid. 

 Tannic acid: Kahlbaum; used a month after its dissolving. Rennet 

 solution (0.01^^), 1 cc+tannic acid solution, 1 cc+milk (1^ CaClz) Ice. 

 Tannic acid concentrations : 



I. 0.003125?^ n. 0.00625?^ HI. 0.0125% IV. 0.025?^ 

 V. 0.05% VI. 0.1% 



Even when freed from protoplasm, proteins of the same origin 

 exhibit the property to combine mutually. On account of this pro- 

 perty, as pointed out already, structural change of a protein molecule 

 is likely to spread to other molecules existing in the same system. 

 It is probable that such an oscillation is also brought about by a loose 

 combination of protein molecules in a solution. If loose combination 

 exists between protein molecules, each molecule may be prevented 

 from behaving of its own accord, and accordingly all the molecules 

 present in a solution may have to act as a single system. On the 

 other hand, as stated repeatedly, since protein molecules possess the 

 structural reversibility, phage or rennin inactivated to a certain extent 

 may be striving to resume its original active structure in resisting 

 the inactivating action of the added substance. These two opposite 

 actions may cause the oscillation. 



The writer has been able to prove that the turbidity produced in 

 a solution of ovalbumin by the addition of tannin shows also an 

 oscillation in the progress of time following the addition (132). It has 

 also been found that the turbidity of a protein solution oscillates with 

 the change of the added amount of sodium chloride (133). 



