1898.] MICEOSCOPICAL JOURNAL. 45 



that microscopical slides are specimens of natural history 

 objects. 



SCIENCE-GOSSIP. 



Amplifier. — Thirty years ag"o Dr. Woodward, of the 

 Army Medical Museum, was deeply interested in perfect- 

 ing- the art of photo-microscopy. The device of introduc- 

 ing- into the body of the microscope an amplifier was so 

 successfully carried out that he was enabled to obtain a 

 greater and more accurate amplification or magnification 

 of the object with a Wales one-sixth than was possible with 

 the Powell and Leland one-fiftieth. A micro-photograph 

 of a frustule of the diatom Pleurosigma angulatum had its 

 markings so resolved by the one-sixth plus the amplifier 

 that they were shown to be hemispherical bosses of silica 

 rather than hexagons, as the one-fiftieth and all other 

 lenses then known made them appear. The result was 

 owing to the superior resolving power of the one-sixth plus 

 the amplifier. A second microscope is infinitely superior 

 to an eye-piece for the amplification of the "real" image. 

 But how do we get it collected. "The line of light falling 

 on the photo-salt in the film spreads by molecular irradia- 

 ation over more area than the actual width of the line of 

 light, and there is also diffused reflection of this line of 

 light by the semi-transparent substance of the film. To 

 these two causes is due the fact that when the details of 

 two structures are too close together in an image of an ob- 

 ject these structures will photograph as one, and thus the 

 detail will be lost. If the new details are to appear the 

 image must be enlarged before it is photographed." — Gage. 



Epithelioma. — Dr. Hartzell reports a case in University 

 Hospital, Philadelphia, of a sixteen-year-old boy who car- 

 ried a pea-shaped ulcer above his cheek for two years. 

 Microscopic sections were made from the border of the 

 ulcer. They revealed a neoplastic structure consisting of 

 fibrous stroma in which were numerous irregular-shaped 

 branching tracts of columnar epithelium, and a round-celled 



