166 PRACTICAL PHOTOMICROGRAPHY. 



power. For photo-micrography, as a matter of course, he uses 

 apochromatics, and always at the highest angle possible con- 

 sistent with contrast between " tissue " and ground. No doubt 

 the old experienced microscopist, accustomed to low-angled 

 glasses, will be sceptical, and may even at first believe in the 

 inferiority of the wide angles, especially if he use an imperfect 

 system of illumination, but we have firm confidence that after 

 a fair trial and a little perseverance and fight with prejudice, 

 the newer glasses will prove victorious, even in the eyes of our 

 fathers of microscopy. If, in any branch, " want of penetra- 

 tion " can be disastrous, surely that branch is the photo-micro- 

 graphic ; yet of all the conditions under which we insist on a 

 wide-angle apochromatic objective, photo-micrography is the 

 chief. 



