1898.] MICROSCOPICAL JOURNAL. 45 



that microscopical slides are specimens of natural history 

 objects. 



SCIENCE-GOSSIP. 



Amplifier. — Thirty years ago 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 

 g-reater and more accurate amplification or mag-nification 

 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, anda round-celled 



