Functional and Ontogenetic Stimuli Alike 305 



essence to functional life proper." 222 This would speak 

 for the gradual accomplishment of the transition from 

 the embryonal to the functional period without any sud- 

 den and precipitate change, and so speaks also for a 

 gradual, hardly noticeable replacement of the ontogenetic 

 stimulus by the functional so that one must suppose the 

 two stimuli to be active simultaneously and in 

 combination. 



So Hyrtle, having cut across the motor nerves of the 

 muscles of one side of the face of a new born rabbit, 

 stated that a year after there was not only atrophy of 

 the muscles but the bones of that side of the head had 

 undergone a surprising arrest of growth. He attributed 

 this arrest to the fact that "after muscular paralysis there 

 was lacking the traction and compression, which provoke 

 living parts of the bone to activity and cause the normal 

 growth of the bone." 223 



Alesandrini and E. H. Weber similarly found in 

 monsters "that in the absence of the anlage of the spinal 

 cord there were lacking in the corresponding nerve ter- 

 ritory both the nerves and the muscles and that the bones 

 and joints belonging to these w r ere abnormally formed, 

 the latter being in part rigid." 224 



It may be remarked here that as some of these parts 

 had attained a certain development even without the 

 functional stimulus, and during the very period in which 

 normally they would have had the co-operation of the 

 functional stimulus, it is therefore clear that if there had 



222 Roux: Zur Orientierung iiber einige Probleme der embry- 

 onalen Entwicklung. Zeitschrift fur Biologic. Bd. XXI; Miinchen, 

 July 1885, P. 503. Gesammelte Abhandlungen, II, P. 231232. 



228 Oscar Hertwig: Die Zelle und die Gewebe. II, P. 175. 



22 *Roux : Der Kampf der Teile im Organismus. P. 51. 



