SUPPOSED TRANSMISSION OF ACQUIRED CHARACTERS 4OI 



black scales, for the germ-plasm would only contain either ' red ' 

 or ' black ' determinants for a certain spot on the wing. 



The theory of determinants will, I believe, supply a very 

 simple explanation of this apparently complicated case, which 

 I consider of great value, because it confirms this theory. 

 Instead of supporting the doctrine of the transmission of 

 somatogenic characters, this example shows how suc/i a process 

 may appa7-ently be brought about, and on what it depends. 

 A somatogenic character is not in this case inherited, but 

 the modifying influence — the temperature — affects the primary 

 constituents of the wings in each ijidi^'idual, — i.e., a part of 

 the soma, — as well as the geri}i-plasni contained in the germ- 

 cells of the animal. It modifies the same determinants in 

 the rudiments of tlie wings of the young chrysalis as in the 

 germ-cells, — namely, those of the wing-scales. The variation 

 cannot be transmitted from the wings to the germ-cells, but only 

 affects the coloration of these organs of the individual in ques- 

 tion ; whereas it is transmitted from the germ-cells to successive 

 generations, and consequently controls the coloration of their 

 wings in so far as this is not again modified by subsequent influ- 

 ences of temperature ; for the same determinants which are now 

 present in the germ-cells of generation I are afterwards passed 

 into the rudiments of the wings in the caterpillar and chrysalis 

 of generation II, and the change which they underwent while 

 lying in generation I may be increased or weakened by the 

 influence of the temperature to which they are exposed after 

 entering into generation II. 



Since warmth aff"ects the whole body, it is not surprising that 

 the determinants which are modified by it should undergo these 

 modifications, whether they are contained in the germ-plasm of a 

 young egg or sperm-cell of the caterpillar, chrysalis, or butterfly, 

 or in certain cells in the rudiments of the wings in the chrysalis 

 or caterpillar. This, however, does not imply that they must 

 undergo the sa7ne amount of variation in both i)laces, for they 

 have not by any means the same environment in the two situa- 

 tions. In the germ-plasm they are grouped amongst thousands 

 of determinants of the species, all of which constitute the germ- 

 plasm ; while in the rudiments of the wings, they are associated 

 with only a few other kinds of determinants, and a time must 

 come when each of them controls a cell by itself and transforms 

 it into a red or a black wing-scale. 



