112 



SCIENCE 



[N. S. ToL. LII. No. 1335 



and that each of these peripheral fibers, in its 

 turn, is divided into two. These relationships 

 may be indicated diagrammatically. One 

 pyramidal fiber may, therefore, be represented 



Fig. 1. 



at the periphery by six branches of axones, 

 each of which is in its turn capable of acting 

 upon an effector. The energy, a, coming 

 down the first fiber in the series, Py, is, ac- 

 cording to the all or none hypothesis, the 

 maximum which the fiber is capable of con- 

 ducting. Similarly, the energy passing over 

 the intercalated (Int.) fiber before its branch- 

 ing is also the maximimi which it is capable 

 of conducting. Suppose that it is equal to a. 

 At the point of branching, the energy con- 

 ducted along each branch must either be 

 brought up to some quantity closely approxi- 

 mating a, or else it must fall to a/3. In the 

 latter case, the energy passing over the 

 proximal unbranched portion of the fiber M 

 must either be brought up to the value a, or 

 else in its turn be close to the value a/3. 

 Going on out to the bifurcation of this fiber, 

 there must again be a raising of the energy 

 in each of the branches to some value closely 

 approximating a, or else it must fall to a 

 value a/6. There is little or no evidence that 

 the energy of the nerve impulse falls off in 

 any such degree in its passage from central 

 system to periphery. The presumption is, 

 therefore, that the efferent distribution path 

 acts as a step-up transformer of energy, al- 

 though the manner of its action is as yet un- 

 known. It should be stated here that the 

 nerve fiber itself furnishes the energy, derived 

 in some manner as yet unknown from its own 

 metabolic processes, and that there is, in all 

 probability, no change in voltage at the ex- 

 pense of the amperage, as in the electrical 

 transformers with which the physicist is 

 familiar. 



Reference to Eanson's^ diagram of the sym- 

 pathetic system will show that the same con- 

 siderations apply there. In fact, the diagram 

 given in this paper was suggested by Ranson's 

 diagrams. 



One more link in the scheme of the step-up 

 transformer may be what Langley has called 

 the receptive substance, interposed, chemic- 

 ally if not histologically, between the motor 

 end plates and the contractile substance in 

 muscle. It is certain that there is a great 

 increase in the energy of a muscle contraction 

 as compared with the energy of the nerve im- 

 pulse, which, starting in the central system, 

 finally evokes the muscle contraction at the 

 periphery. It seems reasonable to suppose, in 

 the light of our present knowledge, that the 

 efferent nerve path is a part of this trans- 

 former system. 



Such general relationships of the energy of 

 the response to the energy changes in the 

 processes preceding the response have long 

 been recognized. Balfour Stewart^ (p. 163) 

 remarks : " We have seen that life is associated 

 with delicately-constructed machines, so that 

 whenever a transmutation of energy is 

 brought about by a living being, could we 

 trace the event back, we should find that the 

 physical antecedent was probably a much less 

 transmutation, while again the antecedent of 

 this would probably be found still less, and 

 so on, as far as we could trace it." We should 

 recognize, however, that such relationships 

 have a limit in the living organism. Other- 

 wise, we would arrive at perpetual motion. 

 F. H. Pike 



Department op Physiology, 

 Columbia Univeksity 



ON SPIRAL NEBULffi 



One of the privileges of the vacation is the 

 opportunity of making one's own tea in one's 

 own vessels. I did so recently, aided by a 

 deep precipitation glass, g, with a lip, I, run- 

 ning far down the sides. On stirring the 



1 Eanson, S. W., 1918, Journal of Comparative 

 Neurology, Vol. 29, p. 306. 



2 Stewart, Balfour, 1874, ' ' The Conservation of 

 Energy," New York, p. 163. 



