CYTOLOGY AND SOCIOLOGY 243 



two great political parties, and show how the " mugwump " is 

 the outcome of a peculiarly exact balancing in the one individual 

 of those two opposing properties of all living matter ; namely, 

 of heredity in the strict sense, whereby, despite environment, the 

 living matter of one generation tends to reproduce with exactitude 

 the characters impressed upon preceding generations, and varia- 

 bility, whereby that living matter is keenly responsive to environ- 

 ment and liable to modification. In most of us one or other 

 of these two properties is in the ascendant. In the words of 

 Gilbert (and Sullivan), we are born " either a little liberal or 

 else a little conservative " ; in the mugwump, thanks to the 

 parental amphimixis, the two properties are accurately balanced. 



However, this is all parenthetic. What I want to impress 

 upon you is that just as nowadays we have learned to regard 

 the atom not as a solid, if almost infinitesimal, mass of matter, 

 but as exhibiting the active play of numerous electrons, so, 

 taking the cell as a unit, we must realize that it is not merely 

 a mass of homogeneous protoplasm, but it is an extraordinary 

 complex of molecules, a little world in itself. 



We have to imagine these molecules as in a state of con- 

 tinuous interaction. Given a stimulus from outside, they set 

 in motion a particular chain of interactions, and we are forced 

 to recognize that, once started, the interaction may continue 

 after the stimulus which has set them in motion has ceased to 

 act. We have, in the first place, then, to recognize the existence 

 of what Dr. Fraser Harris has spoken of as the inertia of living 

 matter, which might perhaps more accurately be spoken of as 

 the momentum of living matter. It is the principle whereby 

 the wheel set rolling continues to rotate until friction brings 

 it to rest. It is the principle that explains the latent period of 

 muscle. If the muscle be resting, as every first-year student 

 knows, a definite period elapses after the passage of the stimulus 

 down the nerve before the muscle passes from the resting to the 

 contracting state. Here it seems to me is the first step ; but 

 something more than this is necessary to induce automatic cell 

 action, and to gain an explanation we pass from the cell to the 

 larger world in a search for parallel phenomena, for, as I have 

 laid down, we may safely draw such parallels. 



Centuries ago when a comet appeared in the sky it had a 

 profound influence on those who beheld it. It was unusual, 



