150 E. E. FREE 



changes in the simple colloids have been traced to this cause and 

 no other adequate explanation is apparent for the case of proto- 

 plasm. It was in connection with this matter of protoplasmic 

 viscosity that the present hypothesis was originally developed 

 and I hope to discuss this phase of the subject in another paper 

 at some future time. 



Note. The contents of this paper have been presented to 

 the members of the journal clubs and seminars of a few univer- 

 sities and discussed with many individual workers. It was the 

 intention of the author to revise it in several important partic- 

 ulars, but as he was ordered abroad on military service before 

 this could be done, his consent was secured to publication in its 

 present form. > 



Among other matters, the author would doubtless have taken 

 into consideration the complex systems which may result when 

 supposedly non-diffusible substances, such as the colloidal 

 carbohydrates and the proteins, are brought together in one mass 

 or system. Such arrangements are to be considered as including 

 minute strands or filaments or lenticular, etc., masses of proteins, 

 carbohydrates, etc., each in its own characteristic foam, honey- 

 comb or sponge condition, the entire complex mutually inter- 

 acting as to water relations. The interpolation of such posi- 

 bilities into the hypothesis presented by Dr. Free would result 

 in the multiplication of the reactions with regard to permeability 

 in a very important manner. 



D. T. MacDougal, 

 F. E. Lloyd. 



