!8 BIOLOGICAL LECTURES. 



strong individual proclivities. If induced or compelled to asso- 

 ciate with other elements, it is ready on the slightest provoca- 

 tion to abandon them and become a free rover. Gunpowder, 

 nitroglycerine, and the fulminates are examples of the qualities 

 of this element to effect disorganization. This element is 

 always one of the constituents of protoplasm, and one might 

 therefore expect it to be unstable and restless, as indeed it is. 

 One of the indications of the rate of activity of any kind in an 

 animal is the rate of elimination of nitrogen. This is empha- 

 sized here in order to make it plain first that the origin of 

 movement in a living thing is to be traced to the energy 

 embodied in the chemical combinations, and second, that par- 

 ticular movements, or at any rate some of them which have 

 been attributed to some directing agency vital force, or life 

 are due likewise to harmonic changes of energy insepar- 

 able from the atoms themselves. 



Movements that result in change of position of the body are 

 called mechanical ; movements that result in the enlargement 

 of the body in one way or another are called growth ; move- 

 ments that result in the organization of another similar body 

 are called reproduction and the similarity of the second to 

 the first has been attributed to heredity, a term expressive of 

 a fact, but embodying no explanation. The conditions in the 

 neighborhood of such growing thing, that react upon it in one 

 way or another, are called its environment ; and this too has 

 been a hazy term, as applicable to one thing as to another ; but 

 in this particular field internal changes necessitate external 

 changes beyond the boundary of the changing body, so as to 

 modify the possible reactions upon it, and in every case it 

 represents but the transformations of energy in the exchange 

 from one kind and amount to another. Here as elsewhere 

 Providence is on the side of the heaviest artillery, and more 

 energy of any given kind always dominates the less. 



When a young duckling waddles into the water the first time 

 the action is attributed to instinct. When the terminal of a 

 rootlet leads off in the direction of moisture and nutriment, is 

 it not instinctive too ? 



In each of the hypotheses devised to account for the phe- 



