The Double Nature of Organisms 225 



in the anatomical structure of the tissues, and of the indi- 

 vidual cells, where the parental characters are set free and 

 a mosaic-like structure results. 



MacFarlane, who has made the most thorough study 

 of the anatomical structure of hybrids, recognizes every- 

 where the principle of duality, and goes so far as to regard 

 every individual vegetative cell of a hybrid as a herma- 

 phrodite formation. And the renowned French investi- 

 gator of hybrids, Naudin, also expressed himself about 

 forty years ago in a similar manner. "L'hyhride est une 

 mosaiqiie vivante," said he; we do not recognize the in- 

 dividual parts as long as they remain intimately blended, 

 but occasionally they separate and then we are able to 

 distinguish them. 



We therefore regard it as established that, in the chil- 

 dren, the inheritances from the fathers and mothers are 

 indeed combined, but not fused into a new entity. Acting 

 always conjointly under ordinary circumstances, they yet 

 do not lose the power of separating occasionally. 



But now arises the question as to what is anatomically 

 visible of this union. Can the dualistic formation be ob- 

 served within the cell ? Do the parental inheritances, here 

 too, lie side by side as twins ? 



The hereditary characters are contained in the nuclei, 

 as was first declared by Haeckel, and later demonstrated 

 by O. Hertwig, and, for plants, by Strasburger. This im- 

 portant law forms, for the present, the basis of the whole 

 anatomical theory of heredity, and is recognized as such 

 by all investigators. We may, therefore, expect to find in 

 the nuclei, as well, the dualism of the parental qualities. 



Every cell, as a rule, possesses a nucleus. This nucleus 

 dominates the life-activity, and although the current func- 

 tions can run their course without it, no new ones can be 



