THE INADEQUACY OF ' NATURAL SELECTIONS 163 



sense that eventually there ceases to he any communication be- 

 tween the two, further than that implied by the supplying of 

 nutriment to the reproductive cells by the somatic cells. The out- 

 come of this argument is that, in the absence of communication, 

 changes induced in the somatic cells, constituting the individual, 

 can not influence the natures of the reproductive cells, and can 

 not therefore be transmitted to posterity. Such is the theory. 

 Now let us look at a few facts some familiar, some unfamiliar. 



His investigations led Pasteur to the positive conclusion that 

 the silkworm diseases are inherited. The transmission from par- 

 ent to offspring resulted, not through any contamination of the 

 surface of the egg by the body of the parent while being deposited, 

 but resulted from infection of the egg itself intrusion of the 

 parasitic organism. Generalized observations concerning the dis- 

 ease called pebrine enabled him to decide by inspection of the 

 eggs which were infected and which were not: certain modifi- 

 cations of form distinguishing the diseased ones. More than this, 

 the infection was proved by microscopical examination of the 

 contents of the egg ; in proof of which he quotes as follows from 

 Dr. Carlo Vittadini : 



" II resulte de mes recherches sur les graines, & 1'epoque oil commence le de- 

 veloppement du germe, que les corpuscles, une fois appams dans I'oeuf, augmen- 

 tent graduellement en nombre, & mesure que 1'embryon se d6veloppe; que, dans 

 les derniers jours de 1'inctibation, I'oauf en est plein, au po.int de faire croire que 

 la majeure partie des granules du jaune se sont transformes en corpuscules. 



" Une autre observation importante est que 1'embryon aussi est souil!6 de cor- 

 puscules, et a un degre tel qu'on peut soupconner que 1'infectiou du jaune tire son 

 origine du germe lui-meme ; en d'autres termes que le germe est primordiale- 

 ment infecte, et porte en lui-meme ces corpuscules tout comme les vers adultes, 

 frappes du meme mal." * 



Thus, then, the substance of the egg, and even its innermost 

 vital part, is permeable by a parasite sufficiently large to be mi- 

 croscopically visible. It is also of course permeable by the invisi- 

 ble molecules of protein, out of which its living tissues are formed, 

 and by absorption of which they subsequently grow. But, accord- 

 ing to Weismann, it is not permeable by those invisible units of 

 protoplasm out of which the vitally active tissues of the parent 

 are constituted : units composed, as we must assume, of variously 

 arranged molecules of protein. So that the big thing may pass, 

 and the little thing may pass, but the intermediate thing may 

 not pass ! 



A fact of kindred nature, unhappily more familiar, may be 

 next brought in evidence. It concerns the transmission of a dis- 

 ease not unfrequent amorig those of unregulated lives. The high- 



* Les Maladies des Vers a Soie, par L. Pasteur, i, 39. 



