HEREDITY, AND THE ORIGIN OF SPECIES. me! 
we have been able to make repeated observations of the 
general principles which govern breaks, or saltations in 
heredity, and to observe in what manner such mutations 
are connected with the origin of species. 
4. Having ascertained at what time in the life-period 
of the individual mutations occur, I have been so fortunate 
as to secure results, demonstrating that mutations may be 
induced in a species not hitherto 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 unavoid- 
able implication 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. 
Lastly 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 spontaneous break- 
ing-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 
whether biologists have been correct in looking for contin- 
uous transformation of species. Judging by analogy we 
Should rather expect to find slight continuous changes oc- 
curring during a long period of time, followed by a some- 
What sudden transformation into a new species, or by 
rapid extinction.” 
In the long-continued narrowing of the range of fluc- 
tuation 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 fulfilment 
of this motion as might be expected when an attempt is 
