494 POPULAR SCIENCE MONTHLY 



2. The power of recovery through generous leeding exhibited by the progeny of indi- 



viduals subjected to famine is so extensive that three generations 01 plenty suc- 

 ceeding one generation of famine are sufficient to bring about the complete recovery 

 of the race from the dwarfing consequent upon a generation of famine. Thus indi- 

 viduals of the fourth generation — the great-grandchildren of the starvelings — are 

 the compeers in every respect of individuals of normal ancestral feeding. It is 

 highly probable, but not yet proved, that recovery is possible even after three 

 generations of famine. 



3. The effects of famine grow less evident the further removed (in heredity) the indi- 



viduals are from its occurrence in their ancestral history. Thus, in two lots having 

 but one underfed generation in 4, a lot having the underfed generation 2 or 3 

 years previous would rank higher in all respects than one whose immediate par- 

 ents were its only underfed ancestors. 



4. A fourth generation on insufficient feeding has not yet been reared successfully in 



two years' trial. It is highly probable that the race cannotsurvive more than three 

 generations of poor nourishment. 



It will be noticed that the differences between the normally fed individuals 

 and those subjected to famine are not species-making differences, as specific 

 characters go with the Lepidoptera, there being no differences in color or pat- 

 terns, or shape or venation of wings, or larval or adult ornamentation. If a 

 species or race of silkworms were named on the basis of characters induced by 

 famine, it would be a ' size ' and ' season ' species — a Lilliputian race of silk- 

 worms having a lengthy metamorphosis. 



While at first glance these experiments might seem to offer an instance of 

 the inheritance of acquired characters, it is, however, apparent that the under- 

 feeding affects the nourishment and full development, not only of visible parts 

 of the body, but also of the germ cells and all internal parts of the body. The 

 germ cells need not be said, therefore, to have been influenced by the acquired 

 somatic characters and to have transmitted them as such, but rather they may 

 be said through their own lessened vitality to have produced progeny with char- 

 acteristics so parallel to those of the parent soma as to make it appear an 

 authentic case of the inheritance of acquired characters. We have, therefore, a 

 case of transmission of imperfect nutrition, not one of true heredity, a distinc- 

 tion made clear by Weismann. Moreover, if acquired characters are really 

 hereditary, their inheritance should last for more than three generations. 



One interesting result of this experiment is that (in so far as silkworm 

 testimony goes) temporary trying conditions do not handicap the race in the 

 long run. It is even conceivable that the ultimate result of famine might be a 

 strengthening of the race (physically speaking), the famine playing the part of 

 a selective agent, preserving only the strong and adaptable. 



Ontogenetic Species 

 Of like nature, but often far greater in degree, are the changes in 

 the individual dependent on differences in food, in nurture or in 

 surroundings generally. In the life of a plant the environmental 

 variations may be so great as apparently to overshadow all the innate 

 characters or peculiarities. With the higher animals the direct effect 

 of environment is proportionately less, and it reaches its minimum 

 among birds and the more specialized insects. Yet no individual of 

 any species is without some traits of variation due entirely to environ- 

 mental influences. In fact heredity does not repeat the traits of the 

 parent, but merely the tendency to develop similar traits under similar 

 conditions. Change utterly the conditions of growth, and the same 

 heredity will show itself in very different results. Strictly speaking, 



