44 THE GERM-PLASM 



tion is not unfounded, inasmuch as several instances of molecular 

 compounds are known in chemistry, e.g., the double salts and 

 the water of crystallisation of salts, in which definite numbers 

 of molecules are always present : this number is even retained 

 in spite of substitution. Thus alum ahvays contains twenty- four 

 molecules of water of crystallisation, and this evidently indicates 

 a degree of affinity between the molecules. We shall have to 

 assume this property for the biophor also, for without it the latter 

 would not be a real unit at all. We shall, moreover, be able 

 to conclude that these degrees of affinity are of various kinds, 

 and that the molecules can combine in many different ways 

 and form groups, so that isomeric molecular compounds are 

 formed. Such isomeric compounds, however, will possess other 

 properties, just as in the isomeric arrangement of atoms in the 

 individual molecule ; and thus we conclude that the special 

 properties of a biophor are to be considered dependent not only 

 on the physico-chemical constitution of the molecule, but also 

 very essentially on their position and relation to one another ; 

 so that one biophor can be changed into another by an altera- 

 tion in the arrangement of its molecules. 



According to this statement there are several kinds of 

 biophors, the diiTerence between which depends on either the 

 absolute relative number of molecules, their chemical constitu- 

 tion (isomerism included), or their grouping; in fact we may 

 say that the number of possible kinds of biopJwrs is nnlimited, 

 just as is the number of conceivable organic molecules. We 

 shall, at any rate, meet with no theoretical difficulties on this 

 score, however large the number of different kinds of biophors 

 may be which we require to explain the theory of heredity. 



The biophors are not., I believe, by any means mere hypo- 

 thetical units; they must exist, for the phenomena of life must 

 be connected w^ith a material unit of some sort. But since the 

 primary vital forces — assimilation and growth — do not proceed 

 spontaneously from either atoms or molecules, there must be a 

 unit of a higher order from which these forces are developed, 

 and this can only consist of a group consisting of a combina- 

 tion of dissimilar molecules. I emphasise this particularly, 

 because a theory of heredity requires so many assumptions which 

 cannot be substantiated that the few fixed points on w'hich we» 

 can rely are doubly valuable. 



These biophors constitute all protoplasm — the morphoplasm 



