264 CORRESPONDENCE. 
attention, and with wide-angled objectives, which recent advances of 
the optician had put at our command,’ 
“This question about the comparative utility of lenses of wide or 
narrow angle is one of the greatest importance to all engaged in, or 
intending to engage in, any of the branches of the study of pathology, 
histology, or biology; to all who own lenses, or who are intending 
to own more... . Now, as is said in the report, there is a wide 
divergence of opinion among microscopists on this subject. While 
a few support Professor Smith, the great majority advocate and 
recommend the use only of small-angle lenses. . . . Dr. W. B. 
Carpenter has the credit of being one of the most influential advocates 
of the small angles. The writer of this is in possession of informa- 
tion that, within a few months, an objective of the highest possible 
air-angle was shown to Dr. Carpenter at his own house, and he 
asserted that he saw a certain histological subject better than ever 
before. Rev. Mr. Dallinger, of Liverpool, and his associate, Dr. 
Drysdale, have been for some years making the most important con- 
tribution to biology ever made. The writer has seen a letter from 
Mr. Dallinger that the flagella of a certain monad had been invisible 
to all objectives save two, both of the highest attainable angular air- 
aperture. Here we have one case of more and one of better. Will 
our American histologists contribute their facts ? ” 
Death of Professor Pancerii—We have to announce the death of 
this distinguished anatomist, which occurred quite recently. He was 
suddenly attacked whilst in the act of addressing his class at the 
University of Naples, and died in a few moments. It is supposed that 
the cause was disease of the heart. 
CORRESPONDENCE. 
Ture MicroscoricAL EXAMINATION OF Bioop STAINs. 
To the Editor of the ‘ Monthly Microscopical Journal.’ 
No. 1835, CurstNutT STREET, PHILADELPHIA, PENN., 
March 14, 1877. 
Dear Sir,—I fear you and your readers are almost as tired of the 
blood question as you are of the angle of aperture controversy ; yet I 
hope you will, in simple justice, allow me to make one remark, in 
reply to your severe editorial comment, in your February number, 
upon my views. 
Permit me to say, that you have been entirely misinformed 
respecting the claim I advance, which is not that we can distinguish 
human blood from that of the guinea-pig or dog, as photographed by 
Dr. Woodward, but only that in regard to stains containing cor- 
puscles within the range of human blood-dises (3359 to g¢op), and 
