MICROSCOPY. i 123 
The preservation of blood absolutely unchanged in appearance 
is essential to a successful study of its structure. Hitherto the 
inadequacy of most students’ microscopes and the necessity for 
immediate and hasty inspection of blood has almost prevented its 
successful study. To these reasons it should be added that only 
the few students who make somewhat of a specialty of this branch 
of science can become sufficiently expert for its more difñcult in- 
vestigations; and the author’s estimate of drying as a means of 
preserving blood, that it is of little or no use, meets with an 
important exception in the case of studies as to the class of ani- 
mals to which a given specimen of blood belongs, and also in the 
determination of the existence of certain diseases. ` For all pur- 
poses, however, it is desirable to preserve the corpuscles in their 
natural state, and osmic acid has been successfully introduced for 
this purpose by Prof. Max Schultz. A film of blood on a glass 
cover is exposed for three minutes to the vapor arising from a bot- 
tle of two per cent. solution of osmic acid; after which it may be 
immediately mounted in a nearly saturated solution of acetate of 
potash. ‘Every corpuscle thus becomes ‘set,’ as it were, in its 
living form.” 
A New Gnrovr or Inxrusorra.— In studying the blood of frogs 
Mr. E. Ray Lankester has sometimes noticed a little parasite which 
was at first mistaken for a very active white blood-corpuscle. This 
new infusorian, which is figured in the “ Quarterly J ournal of 
Microscopical Science” for October last under the name of Undu- 
lina ranarum, is a minute pyriform sac, the narrower end of which 
is somewhat twisted and spirally bent round upon itself, giving it 
a strikingly shell-like appearance. It has neither mouth nor cilia, 
but instead of the latter a broad, toothed, undulating membrane 
which makes it the type of a new group of infusoria. 
Structure or Mrxute Orcantsms.— The “ New York Evange- 
list,” in describing with very natural admiration the beautiful 
Moller’s Type Plate (the diatoms of which, by the way, are un- 
doubtedly vegetable and not animal organisms), raises again the - 
question whether these minute organisms may not be possessed of 
organs and tastes corresponding to those of higher aminals. Per- 
Sons having an intelligent interest in the science of microscopy, 
but unfamiliar with its details, cannot be too well assured that 
extreme simplicity of the lower organisms is a fact of positive, 
