12 The Microscope. 



their Continental stands and use their small-angled objectives 

 over histological objects. At the first opening of the book they 

 will come face to face with two phototypes that may not con- 

 vince them, for they are " much set in their ways," but which 

 are to the reasonable reader as convincing as that the noon-day 

 sun is bright. In the frontispiece the ke^^-note of the work is 

 sounded. Here it is as heard in the explanation of the plate : 

 " This object has been photographed for the purpose of exposing 

 the fallacy which underlies the generally accepted statement 

 that ' low-angled ' glasses are the most suitable for histological 

 purposes . . . On carefully examining this figure it will be 

 noticed that it is almost impossible to trace the outline of any 

 particular endothelium cell because its image is confused with 

 that of the lower side of the pipe. In a monocular microscopi- 

 cal image a perspective view does not exist; it is therefore 

 better to use a wide-angled lens, and so obtain a clear view of a 

 thin plane at one time, and educate the mind to appreciate 

 solidity by means of focal adjustment. It will be admitted that 

 unless one approaches figure 7 with a preconceived idea of what 

 an endothelium cell is like, the knowledge gained will be small 

 indeed." In figure 8 is shown the same object (a small vessel 

 from the bladder of a frog), with less amplification, but with a 

 wide-angled objective. " Here only the upper surface of the 

 pipe is seen, so that the outline of the endothelium cells can be 

 clearly traced. The circular elastic tissue is also displayed." 



The seventh edition of this microscopical classic is not only 

 a new edition, but almost entirely a new book. It contains the 

 latest microscopical information, presented in a pleasing manner, 

 much abstruse mathematics prepared by a master hand for the 

 easy assimilation of the less-learned reader, and its whole teach- 

 ing is exactly what The Microscope has been trying to teach its 

 constituency, namely, get the best, aspire to the highest, and 

 make the most of the optical tools at 3^our disposal. In a 

 personal letter to the writer, Dr. Dallinger, the illustrious editor, 

 says in reference to the book: " The first seven chapters I have 

 personally wholly re-written, giving an English touch to all the 

 German theory, rendering all Abbe's work for twenty years into 

 (I hope) an intelligible English summary, and giving the latest 

 principles and practice, the technology of twenty-five years of 

 experience in the use of the microscope, while I have strongly re- 



