290 HOW TO WORK 



200 diameters, will increase the image at this point to 215, and my 

 o-V n > instead of magnifying about 1,600 diameters, increases thv. 

 image of the object to 1,800 diameters. By increasing the length 

 of the tube of the microscope between four and five inches, I obtain 

 an amplification amounting to 3,000 diameters, and the -j-oVo ^ an 

 inch becomes upwards of three inches in length, p. 287. The tube 

 of the microscope bears increasing four or five inches in length even 

 with the fiftieth, and in this way I have been able to see points in an 

 object which I had failed to observe when using the twenty-fifth. 



In plates LVII, LVIII, LXI, LXIII, some coloured figures 

 are given. These have been produced by a double printing. 

 Several different hues may be obtained without difficulty as in litho- 

 graphic colour printing, but in printing large numbers, it need 

 scarcely be said block printing is much cheaper than lithographic 

 work. 



NEW METHOD OF PREPARING SPECIMENS FOR RESEARCHES WITH 

 THE AID OF THE HIGHEST MAGNIFYING POWERS YET MADE. 



It has long been my opinion that real advance in our knowledge 

 of minute structure depends mainly upon improvements in the 

 methods of demonstration. Experiment has proved that the arrange- 

 ment of the elements of the tissues of man and the higher animals in 

 the recent state is not to be made out by examination in water, serum, 

 vitreous humour, and other solutions usually employed for this 

 purpose. In very many cases the refractive power of the tissue and 

 other physical characters interfere with the clear demonstration of its 

 structure. In the controversy concerning the arrangement of nerves 

 in voluntary muscle, an independent reader would not fail to notice 

 that different plans of demonstration had been employed.* This, in 

 some measure, explains the great discrepancy of the results arrived at. 

 It is also to be noticed that those who deny the truth of facts stated 

 by previous writers, have not in all cases adopted the method of in- 

 vestigation recommended by them. 



In my first paper upon the distribution of nerves and muscle, I 

 stated that the arrangement there described could not be seen unless 

 a particular process of preparation was followed, yet my opponents 

 have not adopted the plan pursued by me. nor even considered the 

 principles upon which its success depends. Nay, although I strongly 

 insisted upon the importance of injecting, partly for the purpose of 

 ensuring the preservative fluid being distributed equally to all parts 

 of the tissue, and partly to prevent the possibility of vessels being 



* Si? 'An Anatomical Controversy,' Archives of Medicine, vol. IV, p. 161. 



