THE PEESIDENT's ADDRESS. 103 



name. The comi^lote life-history of almost every one of these 

 microscopic living things — whether plant or animal, or neither one 

 nor the other, but something between the two — has yet to be 

 traced out and written. Much has been attempted. Something 

 has been achieved. Much more remains to be done. Let me point 

 out one direction in which experiment may usefully be brought to 

 the aid of simple observation. 



The influence of external circumstances on the development of 

 the individual, and more remotely on the more or less lasting 

 characteristics of the species, is a subject fraught with interest. It 

 is one too which has of late engaged the earnest attention of 

 students in every department of natural history. 



Now, the living beings which especially come under the ken of 

 the microscopist are of all others the easiest to watch throughout 

 the whole period of their several existences. Their metamorphoses 

 are speedy, their lives are short, and generation very quickly follows 

 generation. Tlieir external conditions may be controlled and regulated 

 to a certain extent with ease. Temperature and light may be varied 

 with some degree of accuracy. Food and atmosphere may be varied 

 also, though perhaps with more difficulty. Surely in such case 

 it must be comparatively easy to make out something as to the 

 power of external circumstances to cause modification of the indi- 

 vidual, and afterwards variation of the so-called species. 



Thus, gentlemen, though I have not told you much of advances 

 made, I have ventured to point out some few out of the many 

 directions in which it seems to me there are some prospects of rich 

 results to the able and industrious worker. 



And now, in one way or other, I have been over the three stock 

 subjects of "the Presidential Address." I venture however to 

 trespass still further upon your indulgence. 



There are at least two ways in which the cause of science may be 

 promoted. First, something new may be ascertained ; secondly, 

 the knowledge of what has been already ascertained may be more 

 widely spread. Now with respect to the progress of microscopical 

 science during the past year, granting that no great discoveries 

 have been made, yet it cannot be doubted that very many persons 

 who before knew nothing of the use of the microscope have learnt 

 something, and many more who knew a little have learnt much. 

 The stream has not deepened perhaps, nor even has it advanced 



