INADEQUACY OF NATURAL SELECTION, ETC. G59 



" But the most important fact for us is, that, though the workers can be 

 jrrouped into castes of different sizes, yet they graduate insensibly into each 

 other, as does the widely-different structure of their jaws." * 



" Graduate insensibly," lie says ; implying that there are very 

 numerous intermediate forms. This is exactly what is to be 

 expected if arrest of nutrition be the cause ; for unless the ants 

 have definite measures, enabling them to stop feeding at just the 

 same stages, it must happen that the stoppage of feeding will be 

 indefinite ; and that, therefore, there will be all gradations 

 between the extreme forms — " insensible gradations," both in size 

 and in jaw-structure. 



In contrast with this interpretation, consider now that of 

 Professor Weismann. From whichever of the two possible sup- 

 positions he sets out, the result is equally fatal. If he is con- 

 sistent, he must say that each of these intermediate forms of 

 workers must have its special set of " determinants," causing its 

 special set of modifications of organs ; for he cannot assume that 

 while perfect females and the extreme types of workers have 

 their different sets of determinants, the intermediate types of 

 workers have not. Hence we are introduced to the strange con- 

 clusion that besides the markedly-distinguished sets of detenni- 

 nants there must be, to produce these intermediate forms, many 

 other sets slightly distinguished from one another — a score or 

 more kinds of germ-plasm in addition to the four chief kinds. 

 Next comes an introduction to the still stranger conclusion, that 

 these numerous kinds of germ-plasm, producing these numerous 

 intermediate forms, are not simply needless but injurious — pro- 

 duce forms not well fitted for either of the functions discharged 

 by the extreme forms : the implication being that natural selec- 

 tion has originated these disadvantageous forms ! If to escape 

 from this necessity for suicide. Professor Weismann accepts the 

 inference that the differences among these numerous intermediate 

 forms are caused by arrested feeding of the larvas at different 

 stages, then l;e is bound to admit that the differences between 

 the extreme forms, and between these and perfect females, are 

 similarly caused. But if he does this, what becomes of his hypo- 

 thesis that the several castes are constitutionally distinct, and 

 result from the operation of natural selection ? Observe, too, 

 that his theory does not even allow him to make this choice ; for 

 we liave clear proof that unlikenesses among the forms of the same 

 species cannot be determined this way or that way by differences 

 of nutrition. English greyhounds and Scotch greyhounds do not 

 differ from one another so much as do the Amazon-workers from 

 the inferior workers, or the workers from the queens. But no 



* Orifm of Spccicc, Cth cd., p. 232. 



