THE PRESIDENT'S ADDRESS. 107 



pointed out, how valuable to us would be their combined labours, 

 and what a characteristic volume would our transactions become. 



There is another field for labour, comparatively uncultivated, 

 available for those who may have neither of the enumerated quali- 

 fications — the abstraction and reduction of the vast mass of British 

 and foreign literature bearing on our subject-matter. Before a 

 student begins a line of inquiry, he wants to know what has been 

 done ; for example — who has investigated the functions and struc- 

 ture of the antennas of insects ? That inquiry alone would occupy 

 weeks, and would lead him through an enormous mass of irrelevant 

 matter, scattered through general and special treatises, monographs, 

 reports, and transactions of innumerable societies. The Quekett 

 could well spare an occasional evening to hear the summarised re- 

 sults of an examination, pursued through these sources, into any 

 branch of sj)ecial study ; and the historical enumeration of previous 

 labours often supplies a valuable stimulus to further investigation. 



Again, permit me to urge on our younger members the impor- 

 tance of mastering the principles on which our instrument is con- 

 structed, for, believe me (although I am well aware we have able 

 and skilful niicroscopists who do not possess this knowledge), it 

 will tend much to a true interpretation of what the microscope dis- 

 closes if we have some knowledge of the optical principles on 

 which it acts. I question if there are many in this room, skilful 

 as they may be in the manipulations of the instrument, who have 

 any clear conception of the principles on which the achromatism is 

 produced, and fewer still who know anything whatever of the laws 

 regulating the phenomena of polarisation. The study of optics, 

 both physical and geometrical, is well worthy the attention of 

 every microscopist, for unless he has mastered these, he is de- 

 pendent in a great degree upon rules and methods, to him 

 more or less empirical, for the use of his instrument, and 

 the interpretation of what it presents to his eye. Many 

 a fallacy which now passes unheeded might be detected if he knew 

 the principles upon which the representation of the object was 

 brought to his view. What insight might be obtained into the 

 internal and molecular structure of objects, if the observer knew 

 thoroughly the properties of polarized light, instead of relying 

 simply on certain empirical rules, and unable to interpret the 

 exceptions. The rules alone might lead him astray, whilst a power 

 of discriminating the exceptions, which a knowledge of principles 

 would give him, might carry him on to further researches and 



