78 
so as to break up the individual grains and form a transparent gelatinous 
mass, afterward diluted with water, so as to afford a complete mixture 
with the solution of the enzymes. The second hypothesis seems reason- 
able, since we already know that different sugars perfectly soluble are 
nevertheless quite differently susceptible to the action of ferments and 
enzymes, and the reason is traced directly to their isomeric condition, i. e., 
to different molcular constitution. There is certainly nothing improbable 
in the thought that a similar variation or isomerism exists among starches. 
Should this explanation, which now seems the only reasonable one to offer, 
be correct, the theoretical value of the observations presented will quite 
equal or exceed any practical application they may possess, since the pos- 
sibility of isomeric starches has not heretofore been entertained. 
A New Puoro-MicroGRAPHIC APPARATUS. By A. W. BITTING. 
While it is possible to make excellent photo-micrographs with simple 
apparatus, a microscope, a camera with a ground glass and a few books 
er blocks to make the necessary adjustments, such arrangements are in- 
adequate for laboratory work. To meet the needs of the laboratory many 
forms of apparatus have been devised, some of which are admirably 
adapted to the particular work for which they are intended. Most of them 
have a limited range of adjustment and not well adapted to all kinds of 
work. 
The object of the writer in constructing a new apparatus was to get 
one more nearly adapted to all laboratory conditions than is now provided. 
The requisites of a good photo-micrographic apparatus are rigidity, 
ease and accuracy of adjustment and adaptibility to all kinds of work. 
The first condition has been met by using metal in the construction, thus 
obviating shrinking, swelling and warping, inherent qualities of wood. 
The second and third requirements have been met in the mechanical con- 
struction. 
The cut shows the stand in working order in the inclined position. 
The apparatus consists of an upright cast-iron post supported by three cast 
legs. The center of this post is bored out to receive the elevating post. 
Near the top is a sprocket wheel, which is turned by a screw and crank. 
A binding screw is also placed in the top to clamp the elevating post 
in position. The upright post, with its legs, stands 28 inches high. The 
