306 DARWINISM TO-DAY. 



records, although his too sharp distinction between structural and 

 functional (so-called "dynamic") characters is not at all helpful. 



The most recent serious treatment of the problem from the neo- 

 Lamarckian side, and one of great interest and real force, is that 

 Montgomery's ^ Montgomery in his book on "The Analysis of 

 explanation of Racial Descent in Animals" (1906). Montgomery- 

 inheritance of contends that there can be no congenital variation- 

 variation, without external stimuli (or hybridisation) to initiate 

 it, because germ-plasm cannot be assumed to set up change inde- 

 pendently and automatically, as this would be almost like the 

 assumption of spontaneous generation. Montgomery says, "When* 

 the process of heredity proceeds unchanged the ontogeny of one 

 individual is just like that of its parent. When a change of the 

 ontogeny occurs, so that the offspring comes to be different from 

 its parent, we say that a variation has appeared in the offspring. 

 This variation, it is thinkable, may have been produced: (i) by- 

 internal growth energies, (2) by external environmental influences, 

 or (3) by a combination of both; and it is necessary to discuss- 

 which one of these is the most probable. 



"There is clearly, in the process of production of variation and 

 mutation, some modification of the normal process of heredity. 

 Since in a number of species it has been shown that all the adult 

 individuals from one locality are not exactly alike, but show meas- 

 urable differences in dimensions, colour, or some other character, 

 it follows that the hereditary process of each such individual must 

 vary correspondingly, even though the variation does not become 

 perceptible until the stage of maturity. The origin of inherited, 

 variation or mutation is then a question of the origin of modifica- 

 tion of the hereditary process. 



"The regularity of the process of heredity is quite comprehensi- 

 ble on the basis of the direct transmission of definite chromosomes 

 in number, form, and quality constant for the species. From cell 

 to cell, from individual to individual, these chromosomes are regu- 

 larly transmitted in a continuous progress, therefore a succession of 

 similar individuals is quite understandable. One germ-cell comes 

 from a preceding one, to our knowledge is never formed from a 

 specialised tissue-cell, so that there is an uninterrupted passage of 

 the germ-plasm through the race. This is Weismann's idea of the 

 continuity of the germ-plasm, which we will paraphrase as the 

 continuity of the chromosomes. 



"A variation to become inherited must then be referable to a 

 modification of the energies of this germ-plasm. The germ-plasm 

 is living substance of proved great importance in the metabolism of: 

 the cell. Though in a sense it appears, from microchemical re- 



