Herrick, Physiological Problems. 369 



issues from it, so that an avenue of less viscid fluid leads to the 

 tube from within. Now the tube is closed or removed. The jet 

 of fluid still impinges on that point where the tube had been con- 

 nected and causes the elastic wall to be distended at that point. 

 This might illustrate in a rude mechanical way the idea above 

 expressed. The impinging force would in the case of the mutila- 

 tion consist of most complex molecular tendencies. 



Naegeli believes that growth (/. e., multiplication of cells) de- 

 pends primarily on the structure of the idioplasm and secondarily 

 on the amount and method of its mixture with the nutritive plasma, 

 and also that'during the development of an organism the idioplasm 

 is continually streaming to the growing parts. 



On a dynamic hypothesis we might suggest that in the vast coor- 

 dinated system of activities (motions) some are by their nature 

 capable of being much more readily affected by activities im- 

 pinging from without, while others are relatively indifferent to 

 such "stimuli." The nature of the responses will depend also 

 on the nature of the motion or the phase it may be in. In cases 

 where the rhvthm of the stimulus and that of the activity of the 

 body are harmonious the latter might be "transparent" to the 

 former, /. e., one would not aff^ect the other. In another case the 

 mode of the bodily activities might be such as to destroy or absorb 

 the extraneous stimulus, being modified or augumented by such 

 absorption. This would be a dynamic explanation of nutrition 

 and growth. 



It may likewise be suggested that these elementary activities 

 difi^er in intensity among themselves and that there will be a neces- 

 sary relation between complexity of form and intensity in any 

 given case. Thus, the same unit of energy or specialized motion 

 may gradually become more complex and in doing so will lose in 

 intensity (or rate), or by becoming involved in a large complex 

 much of its intensity may be sacrificed to the maintenance of 

 equilibrium. Moreover, the increase in size if a motor unit 

 (amplitude of motion) due (let us say) to absorption of suitable 

 impinging impulses may cause the figure to pass a critical phase 

 and so give rise to a separation into two concordant associated 

 units of motion, such as could be conceived in case of fission of a 

 cell. 



Credit is due Naegeli for making prominent the fact that the 

 specific value of the inheritable substance does not arise from 



