ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
257 
near the under surface of the stage. The combination gives an excellent 
dark-ground illumination. 
New cheap Centering Substage. — Mr. E. M. Nelson’s substage, 
exhibited at the last November meeting,* is made thus: — The substage 
tube is made 1/4 in. larger in diameter than usual; a smaller tube, 
which holds the condenser, fits in this ; this second tube has a largo 
flange on the top, which prevents it passing through the large substage 
tube. A screw is cut on the bottom of the inner tube, and a flange 
similar to the upper one screws on. Obviously, therefore, by screvving 
the lower flange tight, the inner tube may be secured in any desired 
position. 
C4) Photomicrography. 
Handy Photomicrographic Camera.! — Mr. W. H. Walmsley writes : 
— Although photography in conjunction with ordinary microscopical 
observations (in other words, photomicrography) has undoubtedly 
grown in usefulness and popularity among workers with the Microscope 
during the past five years, there can be no doubt that its aid is very 
sparingly employed — a fact greatly to be regretted. For it is quite self- 
evident that the value of any microscopical research would be greatly 
enhanced, not only to the observer himself, but to his readers (in the 
event of his work being published), by full and accurate illustrations. 
Very few microscopists are competent draughtsmen, or capable of making 
drawings of objects under the lens at all correctly, or even presentable 
as illustrations thereof. And a drawing thus made is always permeated 
more or less by the imagination of the artist ; so that the greater his 
skill in that direction the more likely is he to introduce features, not as 
rendered by the tube, but as he thinks he sees them. To be sure, photo- 
graphic reproductions of microscopic objects are in a majority of 
cases not by any means perfect, or what one could desire, but they are 
vastly superior to almost any drawings in their accurate delineation of 
the various features of the specimen. The saving of time is another 
most important feature, as a dozen negatives may be taken in less time 
than that required to make a single careful drawing. 
In the days of the old “ wet-plate,” the comparative insensitiveness of 
which precluded the use of a lamp as the illuminator, only those possess- 
ing a well-filled pocket-book or having access to the resources of a govern- 
mental or college laboratory could avail themselves of the aid of photo- 
graphy in connection with the Microscope. But the modern gelatin 
“ dry plate ” has placed in the hands of every one a cheap and efficient 
means of doing the highest class of work readily and perfectly. The 
very highest powers may be used with the light from an ordinary 
petroleum lamp. I have a print from a negative of Pleurosigma angulatum 
magnified 2400 diameters, by Spencer’s 1/10 homogeneous objective; 
the illuminant being an ordinary single wick coal-oil lamp. It is the 
work of Dr. J. E. Baker, of Wyoming, Ohio, and is fully equal to the 
best work given to the microscopic world during the past six months. 
Why, then, has the use of photography not become more general 
* See this Journal, 1890, p. 838. 
f Amer. Mon. Micr. Journ., xi. (1890) pp. 257- 61 ; and Proc. Amer. Soc. Micr., 
xii. (1890) pp. 69-74. 
1891. & 
