662 Organic Physics. [August, 



also be transmitted ; therefore every successive tn:ns mission 

 favors the formation of a new adaptation to nature. If the change 

 of organization be a muscular one, and a new movement of some 

 part of the outer body be gained, the use of this movement may 

 be of decided advantage to the animal, and if it be transmitted 

 through a sufficient number of generations, new instinctive habits 

 are likely to arise. If it be a nervous one, some new mental en- 

 ergy may be gained, which must struggle with the hereditary 

 muscular habits. It may be a new phase of nutritive or repro- 

 ductive energy, but whatever it be it is not impossible but it may 

 succeed in establishing itself against the two opposing influences 

 of instinctive habits normal to the species, and of imperfect 

 reproductive energy. 



Such an anomaly might be preserved without change in the 

 surrounding conditions of nature, but would be specially likely 

 to be preserved under such changes in the environment as favor 

 variation in the normal offspring of the species. And by this 

 means new species might arise through single great deviations 

 from the specific type, as well as in the more general method of 

 successive slight deviations. 



The chances are, doubtless, strongly against the hereditary 

 preservation of an anomalous feature, while the natural condi- 

 tions remain unchanged. But it seems quite possible that if a 

 marked change in conditions occur, or if a group of animals of 

 some fixed type be moved to a new locality, to whose condi- 

 tions they are not fully adapted, considerable organic changes 

 might take place rapidly instead of with the slowness ordinarily 

 supposed. For it is certainly not improbable that the inharmony 

 between the animal and its surrounding conditions might strongly 

 affect its internal organization and thus favor the formation of 

 anomalous embryos. And some of these abnormal offspring, con- 

 siderably varied from the normal type, might be particularly 

 adapted to the surrounding conditions. If so, they would have 

 an advantage over the normal forms, and their new powers would 

 have a like advantage over the hereditary or instinctive tendencies. 



Such an anomaly, if transmitted to descendants, would possibly 

 constitute a specific change in organization at a single step, while 

 the new, well adapted variation might rapidly replace the old, ill 

 adapted normal form. 



The evolution of new species in this manner could but rarely 



