1879.] NATURAL SCIENCES OF PHILADELPHIA. 39 



the worker-life enwrapped in the egg. But it appears quite im- 

 possible to comprehend how any structural modifications could 

 act from the worker upon the queen in order to thus react upon a 

 succeeding generation of workers. The illustrations which Dr. 

 Darwin cites, 1 the variation of domestic cattle by interbreeding, 

 and M. Verlot's experiments with certain double annual flowers, 

 if admitted to throw some light upon the inquiry, yet require an 

 efficient superintending human intelligence, which cannot be sup- 

 posed to have its analogue in the perpetuation and development of 

 ant forms, unless, indeed, we may believe that the evolution 

 hypothesis implies and requires the interposition of a Personal 

 Intelligence infinitely superior to that of both ant and man. 



The precise sense in which the workers may be called " sterile" 

 admits of some question. Sir John Lubbock has recently shown 

 that parthenogenetic eggs are sometimes produced by worker-ants 

 in artificial formicaries, from which males alone are hatched. This 

 is according to the analogy of other Hymenopters, as for example, 

 bees and wasps. Here, then, there may be possible escape from 

 Dr. Darwin's difficulty more satisfactory than that which he him- 

 self suggests; for it is conceivable that an opportunity might thus 

 be opened for the transmission of a profitable variation which 

 might arise in a worker. Still, the difficulty appears impassable. 

 One must suppose the growth and maturity of one such parthe- 

 nogenetic male, produced from a worker with such useful modifi- 

 cation, to have been contemporaneous with the maturity of the 

 females of a "swarm;" this male, together with the males hatched 

 directly from eggs laid by the queen shall have gone forth, as is 



the habit of ants, in the regular marriage flight, or ''swarming 



> 



and therein shall have met a virgin queen. As the modification 

 thus supposed to be transmitted, must, on the hypothesis, be very 

 minute, it could have been saved from obliteration, only by sup- 

 posing it fortified by the recurrence of other contingencies of like 

 character in succeeding generations. Mr. McCook therefore con- 

 cluded that the development by natural selection, according to 

 Dr. Darwin's hypothesis, of so many and widely varied forms as 

 exist in the cutting ant, requires a series of contingencies so 

 multiplied and remote as to forbid a reasonable hope of its prob- 

 able occurrence, even with the additional favoring circumstance 

 of occasional males parthenogenetically produced. 



He added that some of the points which Dr. Darwin had 

 raised as to the structure of the driver ant of Africa were being 

 carefully examined by him in the case of Atla fervens, with the 

 best microscopic helps at his command. Thus far, however, after 

 a quite careful examination, nothing that can suggest the idea of 

 an interblending of the castes by rudimentary forms had been dis- 

 covered. The lowest castes of minims, in all specimens examined, 

 with special reference to the mouth organs and eyes, showed the 



1 Origin of Species, p. 227. 



