1062 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [82] 



when possibly the nucleus was the center receptive of external impres- 

 sions, the reflex energies being in turn propagated from it. " While all 

 of the foregoing is speculation only, it helps us greatly to understand 

 some of the phenomena encountered in the course of the development 

 of new organs, and aids in giving us a somewhat clearer comprehension 

 of what is meant by such terms as "automatic" and "voluntary actions." 

 Enlarging upon what has been said above, it may be said that automa- 

 tism is pronounced in certain organs directly in proportion to the grade 

 of specialization attained by the animal, and that the automatism of 

 tissues is due to the survival not only of the protozoan grade of differ- 

 entiation of their elements, but literally to the survival of elements that 

 are in detail structurally comparable to Protozoa. 



It will thus be seen that an action which had its origin, we will say, 

 in an effort of the will of a higher animal as ordinarily understood, has 

 evoked a secondary set of phenomena which had their origin in an au- 

 tomatic set of organic elements, and which have at their command the 

 vaso-motor and vaso-accelerator systems in such higher forms. When 

 such an adjustment and distribution of functional effort become ap- 

 proximately stable, the species itself becomes approximately so. Let 

 any new demand of the environment arise, however, and a recoordiua- 

 tion of the functions must take place, which leads to a redistribution of 

 organic matter and organic motion, which must continue until such a 

 recoordmation is completed. 



The method of recoordiuatiou seems to be contemporaneously incres- 

 cent and decrescent in different i)arts of an organism by small degrees, 

 and these two processes are apt to affect each other reciprocally ; that 

 is, while one part is growing aixl becoming able to assume its functiou, 

 some other structure which previously had the same or a similar func- 

 tion is degenerating, just as we saw that the permanent caudal replaces 

 by such a jirocess of substitution the lophocercal tail of larval fishes. 

 Other instances occur where the atrophy is complete, and no structure 

 functionally comparable is developed, as in the case of the larvse of 

 Anurous Batrachians, in which total atrophy of the larval tail takes 

 place, in consequence of a process of physiological disintegration of this 

 part, which occurs relatively late, and in the course of which the mate- 

 rial so torn down is reintegrated into new structures near bj", having a 

 totally different function, as in the case of the hind limbs of these ani- 

 mals, wliich violate the general rule which obtains amongst the embryos 

 of Vcrtehrata by budding out as paired rudiments before any traces of 

 front limbs have shown themselves externally, they being concealed 

 under the opercular membrane. The tendency of all other vertebrate 

 embryos is to develop the anterior limbs first; and even in tlie case of 

 the Kangaroo, among mammals which have the hind limbs so dispro- 

 portionally enlarged in the adult, their rudiments in the very imma- 

 ture embryo taken from the uterus of the j)arent are, according to Chai)- 



