HEREDITY, AND THE ORIGIN OF SPECIES — MACDOUGAL. 523 



volume, into a connected and meaningful whole, and, best of all, it 

 brings the subject anew into a condition where it is amenable to 

 experimental methods, in the laboratory and experimental garden. 



3. As a result of the theoretical conceptions offered us we hate been 

 able to make repeated observation^ of the general principles which 

 govern breaks, or saltations in heredity, and to observe in what man- 

 ner such mutations are connected with the origin of species. 



4. Having ascertained at what time in the life period of the indi- 

 vidual mutations occur, I have been so fortunate as to secure results 

 demonstrating that mutations may be induced in a species not hith- 

 erto active in this respect and that it is possible to call out new 

 species by the intervention of external agents during the critical 

 period. 



5. Not less important than the foregoing is the unavoidable im- 

 plication that breaks, saltations, or discontinuous action may be 

 caused in inheritance by forces external to the protoplasts and cells 

 which are the true bearers of the hereditary characters. 



6. It is of the greatest interest to note that in the effort to correlate 

 the larger generalizations in the various departments of science in 

 the concept of mutation we have hit upon a principle strongly favored 

 by a modern system of mathematics, well exemplified by the spon- 

 taneous breaking up and rearrangement of the complex atoms in 

 radium, uranium, and allied metals, and which has been recognized 

 by Prof. George Darwin, the physicist, in the following words: 



These considerations lead me to express a doubt wlietlier biologists have 

 been correct in looking for continuous transformation of species. Judging by 

 analogy we should rather expect to find slight continuous changes occurring 

 during a long period of time, followed by a somewhat sudden transformation 

 into a new species, or by rapid extinction. 



In the long-continued narrowing of the range of fluctuation in the 

 various organs, coming to saltations, or direct origination of new 

 forms, as the plant passes from generation to generation, we have as 

 perfect a fulfillment of this motion as might be expected when an 

 attempt is made to interpret the action of the living by the properties 

 of the nonliving. 



The most alluring feature of the whole matter, however, lies in the 

 possibility that when the nature of the induced changes is once ascer- 

 tained the inductive agents might be applied in such manner as to 

 guide the course of development, and thus actually control the evolu- 

 tion of organisms. By such methods man, the conscious organism, 

 might assume a dominating role in the world of organisms and create 

 relations among living things not now existent. 



