H. J. Clark on the Microscope. 39 
. For the last six months I have used one of the most ey 
mproved microscopes, made by Mr. Charles A. Spencer of 
Cannel N. Y.; and with this, between three and four ose 
ago, I again attempted to solve the mystery of the glandular 
dots is with the most complete success. 
When the ous was brought to bear upon the inner surface 
of the dot, the innermost ring (B, C, a) of the perforation ap- 
peared first : a little deeper, ‘the next outer one (>) came into 
view, whilst the innermost (a) disappeared ; — still deeper the 
last (d) passed from my sight, and the faint ring (c) of my old 
observations ont out sharply and alent, as an exterior circle 
to the two othe 
T also oni ad, when passing from the innermost circle (a) to 
the outermost (c), that the widening was gradual; and so, too, 
did it appear in the transit from the second ring () to the: outer- 
most (c). This gave me the clew to the sage eR Ilsaw 
that these rings were not the expression of a le perforation, 
but of the outwardly curled edge of this caecin shaped in 
such a way as to form a sort of trumpet mouth. 
Although I would not trust to a transverse section alone, yet I 
found that it confirmed me in my views as explained above. 
_ The figures which I have given,—namely, a een section 
z (®) with dotted lines projected upon a face view (C) of the dot, 
I think will s aap e to illustrate what I betiose: to be the true 
relations of these ri 
difference between the objectives of the two microscopes, 
compare the action of the —. of Oberhaeuser to the manner 
Engli do: . 
tinued rivalship and growing superiority, he determined to test his skill to the ut- 
most. He therefore, in 1857, requested me to visit Canastota, in order to consult 
8 , and advise him as to the nature of the work for which w es to 
his instrumeuts, This eee resulted in the conelusion that we must have 
three sets of objectives;—one with the ong wie flat field: a second. of the like 
it together 
third with a depthing focus extending as far as possibl that of the the ordinary 
pur rel 
. siioed of the yi hah Pires of 
various imvestigation, but a ose convenienc 
of clint one which the long use of that instrument has taught us, to facilitate tha 
a rect pie inns be in its normal condition, and in ite element, that we 
may be no longer com to represent the tortured figures of a crushed body ar 
dismembered organism, ™ 
