WORK WITH THE HIGHER " POWERS." 245 



this last display is as false, as to many it has been ac- 

 ceptable. Now let down the obliquity of the illumina- 

 tion, as indicated by the line I-J; the effect is noted on 

 the sketch at L, and with a first class high balsam angled 

 objective and an eye well trained, it may be that the 

 striae are not only discernable in the microscope, but the 

 observer will further be able to note the intervening 

 spaces also; and this, too, which the certain knowledge 

 that of the varying condition set forth, the latter dis- 

 play is not only the most satisfactory in general terms, 

 but the most truthful. It is also apparent that the 

 more we decrease the angle of the illuminating beam 

 the louder the call on' the defining power of the object 

 glass and the greater the demand for education on the 

 part of the eye. In other words, the expert, all other 

 things being equal, with a pair of eyes trained by long 

 practice in his profession, has the better chance of see- 

 ing things as they actually are. From the illustration 

 given we deduce several propositions, viz: 



First, it is always better to see structure somehow 

 than not at all. Let those addicted solely to the use 

 of narrow apertures ponder this well. 



Secondly, when engaged in investigations of " diffi- 

 cult" structure similar to the case presented, and calling 

 at the best for light of considerable obliquity, the less 

 of the obliquity, as a rule, and within certain limits, the 

 better ; and the more perfect the education of the eye 

 the less will be the call above mentioned. 



Third, the higher the balsam angle of the glass the 

 LESS will be the obliquity required. Let those who 



