88 THOUGHTS ON NATURAL PHILOSOPHY. 



All resulting in inanimate and animated nature as at present 

 existing and changing. 



The X, or original cause (if any) of matter, in motion, is 

 left open to speculation and proof. Predicate what you may 

 as to this, the mode of expression, the natural manifestation 

 (in a material universe and with material beings) is by material 

 motion. 



Heredity. Weismann's " unalterable " germ-plasm. The 

 chromatin, Professor Weismann says, grows. A tree also 

 grows, and from other matter forms, by physical force and 

 law, what we term wood, and a tree, but talk of unalterable 

 trees would not be a satisfactory explanation, or strictly true ; 

 and as something does not grow out of nothing in living 

 cells, the chromatin grows out of other matter that becomes 

 chromatin. Nature, according to Weismann, is continually 

 making new chromatin, and has been doing so from the first 

 appearance of that substance. The word "unalterable" used, 

 in an unrestricted sense, with regard to chromatin is con- 

 sequently incorrect. It is evident that the chromatin is alter- 

 able, in the sense that the fresh chromatin is new chromatin, 

 made out of other matter than the old. 



Another point is, that to say the germ-plasm is the cause 

 of heredity (although it may be interesting biologically) cannot 

 be regarded philosophically as a satisfactory explanation, as 

 we shall see if we examine the subject closely. Germ-plasm 

 is merely a compound word applied to certain arrangements 

 by nature of material portions moving at certain speeds and in 

 certain ways, acting and reacting on one another, and upon 

 and by material forces within and without the cells. Weis- 

 mann draws attention to the importance of these forces, in 

 the cases of pigeons, ivy, etc., and it is not difficult for the 

 student (if he is not led astray by an " unalterable " theory) to 

 sift from the other interesting statements and arguments, etc., 



