PKOBLEMS OF HEREDITY — APERT. 411 



fill than maternal heredity; the origin from protoplasm carries very 

 little weight from the standpoint of heredity; what really matters is 

 the origin of the seed. 



Since the seed is formed from two half seeds blended together, that 

 explains how it bears in it two hereditary characters at the same time, 

 as Mendel has shown. The Mendel formulas RR, E-B, BB are, then, 

 in exact accord with tiiat which the microscope reveals to us of the 

 embryological mechanism. 



In showing you the Mendel laws we have supposed a simple case 

 in which the parents differ only in a single character, the coloration, 

 " R," and the albinism, " B." In reality there are a very great num- 

 ber of characters that make up the noyau, and each one is double 

 in each cell, as much from the father as from the mother. In the 

 cells from the father each double character is formed of an element 

 proceeding from the paternal grandfather and of an element pro- 

 ceeding from the paternal grandmother, one of the two being latent. 

 Then, from the expulsion of the polar globule one of the two ele- 

 ments of each character is expelled, and the expulsion bears by chance 

 on the elements coming from the paternal grandfather on the ele- 

 ments coming from the paternal grandmother. The same happens 

 in the mother's cells. Finally the cellular egg permits of a very 

 great number of juxtaposition characters. The half comes from the 

 father, half from the mother, and half between them are latent. 

 But the proportions due to each of the grandparents are not fixed; 

 they are given up to chance by the expidsion of the polar globule, 

 and it is only when one considers the average results on a great num- 

 ber of subjects that the chances in an inverse sense balance each other 

 and you arrive at the law of Galton ; that is to say, one-sixteenth com- 

 ing from each grandparent, one-sixty-fourth coming from each great- 

 grandfather, etc. One can compare the juxtaposition in the de- 

 scendant of the characters of paternal and maternal origin to a 

 double mosaic, each one formed from little blocks of marble, added 

 two by two ; that which is under the corresponding block is the latent 

 character, the other is tlie dominant character species. 



In the same animal species the design of the mosaic remains always 

 the same, but the matter of which each block is composed varies 

 according to the individual. Two brothers resemble each other, be- 

 cause the blocks selected to compose their mosaic are taken from the 

 two identical sources; but they resemble each other incompletely 

 because the chance which provides for the distribution of the blocks 

 proceeding from the grandparents and for the elimination of half of 

 each gives changeable results; the half of the blocks are eliminated, 

 and it is not always the same ones which are eliminated. It is, how- 

 ever, a case where the resemblance between the two brothers is strik- 



