PROBLEMS OF HEREDITY — APEET. 409 



mice (dominant) with dancing mice, (dominated), in the union of 

 bay horses (dominating) and sorrel horses (dominated), in the 

 union of a single-comb hen (dominating) .with a double-comb hen 

 (dominated), etc., and finally in the human species. In the human 

 species verification of these laws can not, you understand, be carried 

 so far. Nevertheless, it seems to be an established fact that light 

 hair and blue eyes are dominated characters in the Mendel sense 

 opposing the black hair and eyes, which are dominating characters; 

 and one can, from that statement, infer from heredity the color of 

 hair and eyes, some conclusions which are being verified almost 

 constantly. In the same manner human albinos comport themselves 

 the same as the white albino mice, and in their union their descend- 

 ants obey the same laws. It is the same with many morphological 

 peculiarities, which conduct themselves some after the manner of 

 dominating characters and others after the manner of dominated 

 characters. In family diseases the morbid character is inherited in 

 certain diseases after the manner of dominating characteristics and 

 in other diseases after the manner of dominated characters. In a 

 word, Mendel's law is very general, from the highest to the lowest 

 forms of life; it applies to a number of characters of varieties that 

 may proceed from morphological, physiological, or pathological 

 characters. 



The discoveries of embryologists have made known how the mech- 

 anism of impregnation explains the Mendel law. By the combina- 

 tion of embryological discoveries and Mendel's discoveries we can 

 state that the mystery of heredity has now ceased to be a mystery; 

 nature has raised for us a new fold of her veil. 



You know that all living beings are formed from the aggregation 

 of very numerous small living elements called cells. Each cell is 

 composed of a tiny mass of living matter, the protoplasm, in the 

 center of a more highly organized part, the " noyau." All living be- 

 ings sprang primitively from a single cell, egg^ or ovule. The 

 simplest of living beings remain all their lives formed of a single 

 cell and reproduce themselves by simple division into two, from 

 the cellular nucleus at first, and from the protoplasm mass later. 

 Heredity among these lower forms of life is explained very naturally, 

 since the two new beings are only, so to speak, a continuation of the 

 primitive being. 



With beings a little more complicated, the cellular egg under- 

 goes successive divisions and produces a great number of cells, which 

 remain agglomerate, and the ensemble reproduces the morphology 

 peculiar to each species. A certain number of cells from the interior 

 of the body are alone susceptible of giving birth to new beings ; they 

 constitute the eggs of the animal or the ovules of the vegetable. 

 Although other cells are differentiated, these reproductive cells have 



