CONCLUSION 329. 



all unnecessary ornaments — in certain insects, even their 

 wings — to the accumulation of reserves to be utilized as food 

 for their eggs. Under these conditions, we have been led to ask 

 whether the determination of sex is not simply a matter of 

 nutrition, and whether it would not therefore be possible to 

 produce either sex at will, or, at least, to foretell, at any given 

 time, which one would appear. There is nothing chimerical 

 about such hopes. In certain Bees, the workers, during the egg- 

 laying season, prepare special cells for those larvae which are 

 to develop into males and for those which are to develop into- 

 females ; and we know that our common Bee can even trans- 

 form, during the course of their evolution, the larva designed to- 

 yield a sterile worker into one that will develop into a fertile 

 female, by means of appropriate nourishment. If this result 

 could be generalized, man could obtain control over a 

 phenomenon which has hitherto seemed to him a profound 

 mystery. If he possessed the power to determine the sex of an 

 organism in its early stages, and knew all the phases through 

 which it must pass, why should he not try to mould it to his will 

 and obtain new forms which he could anticipate in advance, 

 instead of merely exploiting the uncertain caprices of cross- 

 breeding ? The infinite number of races of Dogs, Fowls, 

 Pigeons, Rabbits, etc., which have been obtained almost by 

 chance, show how readily species respond to experiments, and, 

 as we have seen, the determination of forms is above all a 

 matter of chemistry. Unfortunately, despite all the advances 

 made in organic chemistry during the last half-century, despite 

 all its successful work in reconstructing varied and complex 

 substances, especially the albuminoids, the problem of the 

 composition, structure, and possible transformations of 

 substances and their mutual relations has by no means been 

 solved, and we have need of its solution if we wish to make 

 rapid progress in the history of life. The very question of the 

 nature of life may soon be removed to an entirely new sphere. 

 For instance, the microbes which pass through porcelain 

 filters and are only visible to the ultra-microscope are con- 

 sidered to be alive. On the other hand, albuminoid substances, 

 do not pass through these filters, because of the size of their 

 molecules. Hence these molecules approach the limits of 

 visibility. It is questionable whether an " organized ' 

 microbe differs very much from a simple chemical compound 

 which, by reason of the size and the small number of its com- 



