138 PROCEEDINGS OF THE AMERICAN ACADEMY 



" For the last six months I have used one of the most recently im- 

 proved microscopes, made by Mr. Charles A. Spencer of Canastota, 

 N. Y. ; and witli this, between three and four months ago, I again 

 attempted to solve the mystery of the glandular dots. This I did with 

 the most complete success. 



" When the focus was brought to bear upon the inner surface of the 

 dot, the innermost ring (B, C, «) of the perforation appeared first; a 

 little deeper, the next outer one (b) came into view, whilst the inner- 

 most (a) disappeared ; and still deeper the last (b) passed from my 

 sight, and the faint ring (c) of my old observations came out sharply 

 and clearly, as an exterior circle to the two others. 



" I also observed, when passing from the innermost circle (a) to the 

 outermost (c), that the widening was gradual; and so, too, did it ap- 

 pear in the transit from the second ring (b) to the outermost (c). This 

 gave me the clew to the whole structure. I saw that these rings were 

 not the expression of a simple perforation, but of the outwardly curled 

 edge of this aperture, shaped in such a way as to form a sort of trum- 

 pet 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 transverse section (B) with 

 dotted lines projected upon a face view (C) of the dot, — I think will 

 suffice to illustrate what I believe to be the true relations of these 

 rings. 



" Now, why was it that the Oberhaeuser instrument would not 

 divulge these relations, when the microscope of Spencer succeeded 

 so satisfactorily ? This I will explain by showing the difference be- 



his instruments. This consultation resulted in the conclusion that we must have 

 three sets of objectives ; — one, with the extremely flat field ; a second of the like 

 kind, but so put together as to allow working with it plunged in water ; and the 

 third with a depthing focus extending as far as possible beyond that of the ordinary 

 kind, for the purpose of viewing objects as a whole, in order to ascertain the rela- 

 tions of their different parts. And now Spencer is devoting those extraordinary 

 abilities, which show him to be a man of genius, to the construction of a microscope 

 which shall embody not only the optical excellences of the different systems of 

 lenses required for the various modes of investigation, but also those conveniences 

 of mounting which the long use of that instrument has taught us, to facilitate the 

 researches upon the living being in its normal condition, in its element, that we 

 may be no longer compelled to represent the tortured figures of a crushed body or 

 dismembered organism. 



