THE MICROSOOrE. 13 



apparatus, was astonished to find that the philosopher's familiar demon 

 was nothing more formidable than the familiar flea. Although the 

 microscope was known so many centuries ago, it is really only within 

 the last 30 years that it has been brought to its present state of per- 

 fection. During that time it has made giant strides, and has advanced 

 from being a scientific toy, giving a confused and coloured image, to 

 its position of pioneer in the investigation of every mystery of nature. 

 I myself can remember when a lens with a quarter-inch focal distance, 

 magnifying 200 diameters, was the highest power known ; and when, 

 about ten years since, a l-26th of an inch lens was manufactured by 

 one of our enterprising opticians, it was considered, and indeed is, a mar- 

 vel of delicate workmanship. Since then, however, they have suc- 

 ceeded in making lenses with a focal distance of l-50th, and within 

 the last few weeks l-70th of an inch, and magnifying between 4,000 

 and 5,000 diameters. I should perhaps mention, that the power of a 

 lens is known by the distance at which it is held from the object mag- 

 nified. This is the instrument with which we now penetrate deeper 

 and deeper into the secrets of nature, and solve doubts and problems 

 which only a few years ago seemed hopeless mysteries. It was by the 

 aid of the microscope M. Trembley first discovered that wonderful 

 creature the hydra, or fresh water polype. I suppose there is no other 

 creature on earth which could undergo and flourish on such treatment 

 as this can. It is nothing that it propagates itself by buds like a 

 plant, and that any part cut ofi" is reproduced ; but you may cut off or 

 slit up its heads, and each piece will produce a new one ; you may 

 cut it in halves or quarters, and produce two or four new creatures ; 

 you may turn it inside out, so that what is now stomach becomes 

 outer skin, and vice versa. You may splice two or three individuals 

 together, head to head, tail to tail, or head of one to the tail of the 

 other, and they will become one animal, not only without injury, but 

 with every sign of placid enjoyment. 



In observations made with the microscope, errors will, of course, 

 sometimes arise, not from any fault of the instrument, but from want 

 of care in observation. Thus there was great dispute some years 

 since as to the real form of the blood corpuscles. The blood consists, 

 as most of you know, of a colourless fluid, in" which float numerous red 

 and white discs called blood corpuscles. Well, some observers de- 

 scribed them as globular, others as flattened discs, a third as slightly 

 convex, a fourth as highly convex, a fifth as concave, &c. ; whereas the 

 form of a corpuscle in freshly drawn blood is a circular disc, with 

 slightly concave surfaces, the difierences of form being produced by 

 maceration, or soaking in water or other fluids, during or before the 

 time of observation. One of the most curious results of microscopic 

 research is the much greater certainty with which it enables us to give 

 to various creatures and plants their right places in creation. Groat 

 obscurity prevailed among the older microscopists as to what they 

 termed animalcules. There ai-e sometimes not less than 27 varieties of 



