
276 THE NORTHERN MICROSCOPIST. 
having regard to Professor Abbe’s statement that objects (such as 
the flagella of Bacteria) which are only a fraction of a wave-length 
in diameter, will necessarily appear to us, not in their proper 
proportions, but with greatly énereased diameters, and that very 
minute striations must appear as if the dark and bright interspaces 
were nearly of egua/ breadth, although in reality not so. 
There are obviously many histological problems, such as the 
question of the structure of muscle, which a proper knowledge of 
this part of the subject may greatly help to elucidate. 
The facts which we now have before us in — to microscopical 
vision, are sufficient to justify the injunction of Professor Abbe that 
“the very first step of every understanding of the Microscope is 
to abandon the gratuitous assumption of our ancestors that micro- 
scopical vision is an imitation of macroscopical, and to become 
familiar with the idea that it is a thing suf generis, in regard to 
which nothing can be legitimately inferred from the optical 
ene connected with bodies of large size.” That there must 
a great deal more yet to be elaborated in regard to the origin 
and nature of the phenomena we have been considering, is obvious, 
and I hope that the attention of our own physicists and micros- 
copists will be directed to a subject of such extensive practical 
bearing, not a theoretical microscopist, but to the large 
class of practical histologists who are entirely dependent upon the 
Microscope for the accuracy of their observations. 
The Aperture of Objectives, 
The “aperture question,” as we all know, gave rise, several 
years ago, to a somewhat acrimonious controversy, not in the 
* Proceedings’ of the Society, but in the unofficial section of its 
Journal, and doubtless there were some Fellows who, at the 
beginning of last year, regarded with no little apprehension the 
prospect of a revival of that controversy. But, notwithstanding the 
warmth with which it was debated in its new form, no one will, I 
am sure, deny the very great value that the renewal of the discus- 
sion—between Mr. Crisp and Mr. Shadbolt—has been in bringing 
to the light what had snc been confined to a few. If any 
one does not now comprehend how an immersion objective can 
nae bing Hig than that of a so ge 39h of ig 
east it cannot be any longer charged is Society, 
means have not been provided to seiieki bo do so, 
The essential difference between the old and the new view of 
aperture is simply, that the former considered only the rays which 
rong objective, while the latter deals with those which emerge 
it. 
The disadvantage of the former method, which estimated the 
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