CHAPTER VI. 



CHOICE OF OBJECTIVES FOR REGULAR WORK. 



Practically, for the past four years, we have confined 

 ourselves to the use of four object-glasses, namely, an 

 inch or two-thirds inch of 45 or 50. A one-half inch 

 of 38. A one-sixth immersion, balsam angle ranging 

 from, say 87 to 95, according to the position of its 

 collar, and a one-tenth immersion having a constant 

 angle of 100. Of the last two glasses, the one-sixth 

 has a working distance of one-fiftieth of an inch. The 

 one-tenth will work readily through covers one-one- 

 hundredth of an inch thick. 



The orthodox theory has been, and I suppose still is, 

 that each worker ought to select his stand, objectives,, 

 accessories, etc., with special reference to the particular 

 line of investigations he may elect to pursue; and since, 

 as before intimated, there may be more or less force 

 attached to such a platform, I neither accept it nor reject 

 it; nor am I " on the fence," halting between two con- 

 flicting opinions. Without going into any special dis- 

 cussion of the pros or cons, we will proceed to state the 

 character of the work in which we have been engaged, 

 accompanied with a recital of the special methods, etc., 

 employed. 



First; we use the microscope constantly from January 

 to December in examination of urinary deposits, and 

 for the study and detection of malignant growths. In 



