8 PEESIDENTIAL ADDERSS BY 



considerable size in its growth, and ma}- be brought about by a sudden decrease in temper- 

 ature, producing an alteration in the vibrations rehitively to the size or density of the 

 molecule. If this be done the imjiress of the new vibration, or the divergence of the lines 

 of rest, continues as the development goes on, and the new plane continues to form as the 

 others do. 



"We know that a solid substance, or even a liquid, which is not crystalline, but which 

 has tbe potentiality of becoming crystalline, will, if subjected to molecular vibrations, 

 gradually become crystalline. This has been found to be the case in wrought iron — not 

 crystalline itself, but becoming crystallized if subjected to molecular vibrations. Many 

 solutions or liquids may be cooled down below their crystallizing points without becoming 

 crystalline if kept at rest, but if molecular vibrations be started therein by a tuuch, the 

 falling in of a particle of dust ur of a crystal of the same material, the mass immediately 

 becomes crystallized. 



The above suggestion of molecular motions may be applied to other cases. In cell 

 growth or development, molecular vibrations are ever present, and each individual particle 

 of matter has its own inherent molecular movement, and if two such be brought together 

 they must inter-act, and the movements of the one be modified more or less by the other, 

 and changes are the result. Thus, if chloral hydrate and camphor, two solids, be brought 

 together and allowed to remain in contact, they melt and become a liquid. 



If we return to our plate of sand, we- find that if we set up one set of vibrations pro- 

 ducing a certain note and then try to alter them to a higher or lower note, we have a 

 difficulty in doing so, and that the plate seems almost to possess a will of its own and to 

 refuse being coerced, as if it were to remember its previous vibrations and fall back into 

 them by habit; yet still by ^persévérance it becomes possible to start the new vibration, 

 and having obtained that, or established the new habit, there is again difficulty in breaking 

 it off to establish another. 



In watching the process of life it has been found that in mineral matters the spherule 

 is the simplest form of matter, so in animal and vegetable life the simple sj^herical cell is 

 the simplest form, and that in the most complex of these structures the simple cell is the 

 origin of the individual, and yet in that simple cell is the potentiality of the most complex 

 form, with all its specific cells of hair, skin, bone, In-ain, muscle or secreting cell. In the 

 congeries of cells, with the numerous functions the different cells are called upon to perform 

 which constitute the perfectly developed individual, we must recognize the fact that all this 

 complicated machinery is the result of the development of the single original coll, and that 

 that cell had in itself the potentiality of all the others. True that in the development of 

 the individual each cell has been altered and adapted to fulfil its peculiar functions bj^ the 

 surrounding circumstances. Would it be too much to say that each individual cell has, like 

 our vibrating plate, been coerced into a habit of vibration, and cannot easily- be turned into 

 a new condition ; yet, by alteration of circumstances, they may be made to do so, as the 

 tubercular deposit is made to grow under the stimulus of the bacillus which brings about 

 these deposits. Nor are these micro-organisms the only things that act on the cells of 

 animals in this waj' ; the presence of the foreign body in the oyster or the mussel-shell 

 determines by their irritation the formation of pearls ; the formation in other animals of 

 swellings, of nodes, even of cancer, by the irritation jn-oducing these new molecular motions. 



In plants we are able to see and watch the developments more easily and to see the 

 results of our experiments. We notice in plants a gradual increase of heat as the plant 



