14 INTRODUCTORY [ch. 



just indeed as we do in the case of attraction or gravitation, 

 on the one hand as a process, and on the other hand as a 

 force. 



In the phenomena of cell-division, in the attractions or repul- 

 sions of the parts of the dividing nucleus and in the " caryokinetic " 

 figures that appear in connection with it, we seem to see in opera- 

 tion forces and the effects of forces, that have, to say the least of 

 it, a close analogy with known physical phenomena ; and to this 

 matter we shall afterwards recur. But though they resemble 

 known physical phenomena, their nature is still the subject of 

 much discussion, and neither the forms produced nor the forces 

 at work can yet be satisfactorily and simply explained. We may 

 readily admit, then, that besides phenomena which are obviously 

 physical in their nature, there are actions visible as well as 

 invisible taking place within living cells which our knowledge 

 does not permit us to ascribe with certainty to any known physical 

 force ; and it may or may not be that these phenomena will yield 

 in time to the methods of physical investigation. Whether or 

 no, it is plain that we have no clear rule or guide as to what is 

 "vital" and what is not; the whole assemblage of so-called vital 

 phenomena, or properties of the organism, cannot be clearly 

 classified into those that are physical in origin and those that are 

 sui generis and peculiar to living things. All we can do meanwhile 

 is to analyse, bit by bit, those parts of the whole to which the 

 ordinary laws of the physical forces more or less obviously and 

 clearly and indubitably apply. 



Morphology then is not only a study of material things and 

 of the forms of material things, but has its dynamical aspect, 

 under which we deal with the interpretation, in terms of force, 

 of the operations of Energy. And here it is well worth while 

 to remark that, in dealing wdth the facts of embryology or the 

 phenomena of inheritance, the common language of the books 

 seems to deal too much with the material elements concerned, as 

 the causes of development, of variation or of hereditary trans- 

 mission. Matter as such produces nothing, changes nothing, does 

 nothing ; and however convenient it may afterwards be to abbre- 

 viate our nomenclature and our descriptions, we must most 

 carefully reahse in the outset that the spermatozoon, the nucleus, 



