448 



edition. In many ways it is a considerable improvement on 

 the third edition, which appeared in 1903. The earlier chapters 

 dealing with the construction of the microscope have been revised 

 and added to, many new illustrations being introduced which 

 represent the requirements of the present microscopist. We 

 hardly think justice is done on p. 35 to the Greenough model 

 of binocular instrument, which is being largely used in research 

 work where only low powers and stereoscopic vision are re- 

 quired. 



Considerable additions have been made in this edition to 

 Part III., which is devoted to a series of articles by specialists 

 <iealing in each case with their own subject of research. 

 This section cannot fail to be of very great service to the 

 working microscopist. The first and most important addition 

 is a very useful introduction to the use of the petrological 

 microscope by F. C. Cheshire. The author explains the phenomena 

 of polarised light and its application by means of the micro- 

 polariscope to the examination of the sections of crystals, and 

 further, the examination and identification of the constituents 

 of rock sections. Mr. Rousselet has considerably added to his 

 section on the collecting and mounting of the Rotifera, while 

 Mr. Soar has given us the benefit of his experience in the study 

 of the Hydrachnidae and Water Mites. 



To the elementary student in the use of his instrument, and as 

 a guide to further work, this handbook will continue to serve the 

 purpose intended by the authors. 



