66 THE AMERICAN MONTHLY [Feb. 



to build the monument will be immediately forthcoming. The 

 committee think that their patience will last for several years 

 if necessary. About 140 dollars are now in hand. 



We shall be pleased to hear from the microscopists regarding 

 the matter and we sincerely trust that they will wish to partici- 

 pate in the rtiemorial. 



MICROSCOPICAL APPARATUS. 



W. "Watson & Sons' New " Parachromatic " Substage 

 Condenser. — This condenser has a total aperture of 1.0 N. A. 

 and has an extremely large Aplanatic Aperture, exceeding .90 

 N. A.. Its power is 2-7 in. and with the front lens removed 

 4-10 in. It is mounted with Iris Diaphragm and Revolving 

 Carrier for Stops for dark ground and oblique illumination. 

 The Iris Diaphragm is divided so as to indicate the N. A. at 

 which the condenser is employed. The diameter of the back 

 lens is 5-8 in. Price complete $18.75. 



Aplanatic Magnifiers. — In addition to W. Watson & Sons' 

 well known regular series they are making Mr. E. M. Nelson's 

 new form, magnifying 15 diameters, which gives great working 

 distance and large aperture. It is believed to be unequalled by 

 any similar lens for working qualities. The price in German 

 Silver mount pocket form is $3.87. For dissecting, in wooden 

 box the price is $3.62. 



BIOLOGICAL NOTES. 



Objections to the Cell Theory. — Adam Sedgwick some 

 time ago published a paper in the Quarterly Journal of Microscop- 

 ical Science, in which he called attention to the apparent inade- 

 quacy of the cell theory, and recent criticism of his position in 

 the matter has induced him to state it more fully in the same 

 publication. He holds with Sachs and others that the phenom- 

 enon of cell formation is not of primary signifiance, but "merely 

 one of the numerous expressions of the formative forces which 

 reside in all matter." The cell theory asserts that the Metazoa 

 are aggregations or colonies of individuals called cells, and de- 



