GENERATION AND INHFJEUTANCE 307 



ever succeed in penetrating into this world of the smallest organic 

 differences, which are now invisible to us? Will, in the future, the 

 means of investigation of the biologists, perhaps the discovery of 

 a more powerful microscope and the mastery of the same, increase 

 the circle of vision of our successors as much as was done by the 

 discovery and mastery of the compound microscope? 



Or, will the chemist succeed in so increasing his knowledge of th'e 

 nature of proteid bodies that we may expect valuable conclusions 

 in regard to the nature and difference of idioplasm, that is, the 

 chromatin substance, from this direction? Who will dare to deter- 

 mine where, and how far away, a limit may be set to the possibility 

 of human knowledge ? 



Far, far away lies in any case the goal, shimmering before us in 

 the distance. For its attainment the individual branches of natural 

 science, from to-day on, must have united themselves, by extension 

 of their borders, to a great united science of nature, as the leading 

 spirits are now trying to consummate. For the investigator who will 

 busy himself with this deepest problem of life must unite in one 

 person biologist, chemist, and physicist, and must master the depths 

 of each of these sciences. 



In looking so far into the future, with its unlimited possibilities, 

 we may well repeat the words with which our great teacher, Carl 

 Ernst von Baer concluded the preface to his Embryology of Ani- 

 mals: "Until then there will still be a prize for many. The palm, 

 however, will be carried off by that fortunate one for whom it is 

 reserved to refer the active power of the animal body to the general 

 laws of life of the world whole. The tree from which his cradle will 

 be fashioned is not yet planted.''' 



