MICROSCOPY. T 
to the inner layers of the shell, and it is upon the inner layer that 
the curious appearances of sporangia, with slightly-branched fila- 
mentous processes proceeding from them, present themselves. 'The 
parasitic view is strengthened by the fact that these markings are 
not found in all parts of the shell, and are certainly accidental. 
Professor Kölliker maintains the fungoid nature of these tubuli in 
shells as well as in other hard tissues of animals, as fish scales, ete. 
Mr. Wedl, another investigator, considers the tubuli in all bivalves 
as produced by vegetable parasites, and that no other interpreta- 
tion can be given. This view does not seem to be borne out by 
the section of another shell which was exhibited, Arca navicula, 
in which the tubuli are always present forming an integrant part ; 
they are disposed in a straight and tolerably regular manner be- 
tween the ridges of the shell; moreover, they have neither the 
‘irregularly branched structure nor the sporangia.” — Monthly Mi- 
croscopicul Journal. 
ADVANCING DeFINITION OF OBJECTIVES. — Tolles has lately made 
a7, immersion objective for the United States Army Medical Mu- 
seum, with which Dr. Woodward has produced photographic prints 
(of Nobert’s bands) that far excel any previous work of the same 
kind. The transparencies on glass are remarkably clear, and 
the paper prints give the lines in such a startling aoa 
of relief that it is difficult, even after feeling of the paper, to 
realize that the lines and the spaces between them are all printed 
on the same plane. This lens seems likely to replace the now 
famous ;}; as a standard of. comparison, the first appeal and the 
last, for high-power lenses of great pretensions for oblique-light 
work. If any maker has made or can make, of which last there is 
no doubt, a lens that will define Nobert’s lines better than this, he 
will confer a favor by presenting to the world proof of the fact. 
The following note from Dr. Woodward explains itself. 
Resoturion or Nosert’s Banp.— I desire to make public the 
fact that, since February, 1872, I have received for inspection from 
Mr. R. B. Tolles of Boston, several objectives ranging from yh 
to >} (maker’s nomenclature) which resolved the nineteenth band 
of the Nobert’s plate in my hands. Last month I received from 
: _ Mr. Tolles an objective made to fill an order of long standing for 
_ the Army Medical Museum. The immersion front of this objec- 
tive (marked y% by the maker) separates the lines of Nobert’s 
