284 HOW TO WORK 



served, it would be most desirable to employ them in carrying out 

 advanced work. 



The use of high powers in studying the peculiar structure of the won- 

 derfully minute diatomacese is too obvious to require special notice here. 



Everyone now aiming at original observation upon the minute 

 structure of living beings, must become skilled in the use of far 

 higher magnifying powers than those formerly considered necessary. 

 But it must be remembered that in this department success depends 

 entirely upon the method of preparation followed. The observer 

 must always begin by using low powers, and as he improves in the 

 mode of making specimens, he may advance to the use of the higher 

 and the highest powers. 



An entirely new field is now opening out for exploration, and a 

 vast number of new anatomical facts will be discovered during the 

 next few years, by the aid of new methods of investigation, and 

 the use of high powers. Original research in this department of 

 natural knowledge is at this time intensely interesting, for the points 

 most open for enquiry involve questions of fundamental importance, 

 which when determined, will give rise to great changes for the 

 better in physiology. Minute anatomy has hitherto been far too 

 little studied by medical practitioners. Is it not obvious that we 

 ought to have a thorough knowledge of mere structure before we 

 begin to discuss action ? But is it not often the case both in phy- 

 siology and medicine that mere speculations are received, and widely 

 taught, which might be completely disproved by anatomical facts 

 already demonstrated ? 



356. Of the Highest magnifying Powers. I include under this 

 term all objectives above the eighth, or which magnify more than 

 400 diameters. In 1859, I was engaged in studying the arrangement 

 of the nerves in voluntary muscle, and succeeded in preparing, by 

 the process given in p. 298, some exceedingly thin sections, in which 

 most delicate nerve fibres could be distinguished, but these were 

 very pale and transparent, and the appearance was such as to lead 

 me to the inference that in many cases apparently single fibres really 

 consisted of several very fine fibres. I desired, therefore, to examine 

 the specimens with a more powerful objective, and I begged Messrs. 

 Powell and Lealand to endeavour to make for me a glass with a mag- 

 nifying power double that of the sixteenth, which they succeeded in 

 making in 1840. In the year 1860, I received from these makers the 

 first twenty-sixth ever made. This lens magnified 1,800 diameters. 

 I have now had great experience of its value, and can speak of it as 

 a most excellent working glass. That it defines exceedingly well, 

 and admits plenty of light, is obvious from the fact that it will allow 



