CHAPTER V 

 REVERSIBILITY 



THE fact of chemical dissociation above a certain tempera- 

 ture is often expressed by saying corresponding phenomena 

 are reversible. 



Given two phenomena A and B (in our case, phenomenon 

 A is the simultaneous presence of carbonate of lime, car- 

 bonic acid and lime within a closed space ; phenomenon B 

 is the existence in the same enclosure of a determined 

 temperature and pressure), we can say that these two 

 phenomena form a reversible whole under the following 

 conditions : 



From direct interference producing in phenomenon B 

 a modification b there will result in phenomenon A a modifica- 

 tion a. Inversely, direct interference producing in pheno- 

 menon A a modification a will result for phenomenon B in 

 the same modification b which had previously brought 

 about in A the modification a. In other words, effects 

 become causes and causes become effects. 



The existence of this reversibility, which has been estab- 

 lished with more or less completeness, between the colloidal 

 state of protoplasms and the chemical nature of their con- 

 stituent substances rules all biology. 



Colloidal activity and chemical activity are exercised, as 

 we have seen, at different degrees of a scale of magnitudes. 

 Consequently, colloidal activity may be influenced by 



