320 Transactions of tJie [Sess. ■ 



and the equally beautiful bird amongst animals, these exhibiting 

 at the same time a minute intricacy of functional action which 

 often baffles the most ardent physiologist to understand. In the 

 organic world, therefore, we have a gradual advance in structural or 

 mechanical details, coupled with a similar advance in the effects or 

 results produced by the mechanism. 



Exactly the same principle applies in the evolution of micro- 

 scopic research. On the one hand are the mechanical arrangements 

 which we call microscopes, and on the other these have, as their 

 desired result or function, the unfolding to us of the secrets locked 

 up in the living things around us. A single lens of glass fitted 

 into a handle was all that the fathers of microscopy had, and 

 we need not wonder, therefore, that the results achieved by them 

 were comparatively simple. But as, according to the principles of 

 organic evolution, the necessity for providing a food-supply, for 

 warding off the attack of enemies, and for becoming better fitted 

 to their surroundings, all conspired to raise animals in the scale of 

 existence ; so, as new wonders were presented to the eye of the 

 early microscopists, the determination possessed them to perfect 

 their instruments, and become yet more familiar with the hidden 

 things around, — in other words, to obtain a knowledge of, and suit 

 themselves to, their environment. 



Let us see then how, side by side, gradual but sure progress has 

 been made in the perfection of instruments of research, and our 

 knowledge of the organisms to which these instruments are ap- 

 plied. In doing so, we must equally take account of the botan- 

 ical and zoological records, for they have expanded in nearly the 

 same ratio. We must bear in mind also, that till two centuries 

 ago, naturalists were content (and perhaps were serving their day 

 well) when they looked only at external naked-eye appearances — 

 noting shape, colour, size, and outside structural details, for it 

 made them thoroughly familiar with the stones, so to speak, with 

 the aid of which the future edifice of exact science was to be built. 



A mere surface knowledge, however, did not long suffice, for some 

 of the more speculative spirits began to inquire, "What is the size 

 of the smallest living thing ? " — while others asked, " What is the 

 explanation of all that we find beneath the surface in those plants 

 and animals that we can see ?" Questions such as these brought to 

 the front two worthy pioneers — Kobert Hooke in our own country, 

 and Leeuwenhoek in Holland. The former published in 1665 an 

 account of what he had been able to discover by aid of a simple 

 mao-nifying- glass, of a water-microscope, and a very primitive 

 compound microscope, his work being entitled ' Micrographia.' 

 Lookino- over it, a student of the present day scarcely knows 

 whether to admire most the difficulties he had to overcome or 

 the wonderful results he achieved. Dedicated to King Charles II., 



