or transformed epithelial cells (formerly called granulecells, or inflammatory corpuscles). In phthisis, the softened tubercle or gangrene may be early detected by the fibres of elastic tissue from the walls of the pulmonary vesicles. The sputa should be first liquefied by boiling with an equal bulk of caustic soda, and then allowed to settle in a conical glass, when a small quantity may be removed by a pipette to a glass slide, covered by thin glass, and placed under the microscope.

The occurrence of fungi in sputa is to be expected whenever there is decay. The Leptothrix buccalis, one form of Pencillium, is common on old epithelial scales of the mouth, and in the later stages of phthisis the sputa will often show fungi in different stages of development. Bacteria and vibriones are also frequent in pus.

In catarrhal pneumonia we may find fibrinous casts of the alveoli of the lungs and epithelial elements.

VII. HINTS ON THE APPLICATION OF THE MICROSCOPE TO 'MATERIA MEDICA AND PHARMACY.

The observations of Dr. Hassall on the detection of adulterations in food,* have prompted similar investigations respecting the purity of medicinal substances. Such examinations cover a wide field of research, chiefly related to micro-chemistry and botany.

The student in this department will do well to provide himself with undoubted specimens of various articles for comparison, although much may be learned from a general examination of any particular drug, etc.

In addition to the recognition of genuine forms of leaves, seeds, roots, etc, and their adulterations, the microscope will often be serviceable in exhibiting the deteriorations to which such articles are subject if kept too long.

Dr. Hale, in the American Journal of Microscopy, shows

Food and its Adulterations. By A. H. Hassall, M.D.

that various causes combine to effect the deterioration of drugs. They may become infested with animalculæ. Leaves and roots may be eaten by insects until all vestige of medicinal power is destroyed. Fungi of various kinds may destroy the tissue. The uncertain action of some pharmaceutical preparations may be thus accounted for.

For the method of examination in this department, as well as in medical jurisprudence, we refer to the foregoing chapters, contenting ourselves here with the remark, that investigations involving life or reputation should never be undertaken without a thorough practical acquaintance with microscopic manipulation and the microscopic sciences. He to whom such work is intrusted, should be able to exhibit and to explain to an intelligent jury what he has seen and what he ought to see.

GLOSSARY.

Aberration (ab, from, and erro, to wander).-The errors resulting from the imperfection of lenses. They are of two kinds, chromatic and spherical aberration.

Abiogenesis.-The dogma of spontaneous generation, or the alleged production of living beings without pre-existing germs.

Absorption Bands.-Transparent substances are usually opaque to certain colored rays of light, that is, absorb them; and when they are submitted to prismatic analysis, this opacity causes gaps in the spectrum. Some substances produce absorption lines of great sharpness, while others have an indistinct outline.

Achromatic.-Destitute of chromatic aberration.

Alternation of Generations, or Metagenesis, is a term employed to designate a cycle of phenomena in which one generation does not produce a form like itself, but one whose progeny are similar to the generation preceding.

Amoeboid Movements.-Motion in minute masses of bioplasm, resembling that of Amaba. It has been recognized in Volvox, in Chara, in the roots of mosses, in fungi, as well as in colorless blood-cells.

Amyloid Infiltration -A filtration of waxy or lardaceous albuminate from the blood among certain tissues of the body.

Angular Aperture.-The angle made by the diameter of the actual aperture of an objective and the distance

from its focal point. A very wide angle of aperture only allows distinct vision of what is exactly in focus, so that when penetration is needed most, as in physiological work, a smaller angle is better than one used for resolution of diatoms and other minutiæ.

Aplanatic.-Destitute of spherical aberration.

Archeus. The term applied by Van Helmont to the specific agent which, according to his theory, presided over vital functions.

Bacteria.-Minute, transparent, rod-like bodies, sometimes jointed, and often exhibiting a vacillating motion. It is probable that they are produced by the germs of fungi in a solution of animal matter.

Bathybius. A term given by Professor Huxley to the slimy matter from the ocean bottom. Doubts have been expressed as to its animal nature.

Binocular (binus, two, and oculus, an eye).-An arrangement of a prism (Wenham's) and eye-pieces for two eyes, so as to produce a stereoscopic effect with the microscope.

Biology (Gr. Bios, life, and logos, a discourse). The study of living beings, including zoology and botany.

Bioplasm.—A term proposed for the elementary substance of organic bodies when actually alive, or living protoplasm.

Blastema. The fluid matter, or plasma, in which, according to the theory of Schleiden and Schwann, nuclei first make their appearance, and then organic cells.

Brunonian Motion.-The molecular movement of fine particles suspended in fluid, first observed by Dr. R. Brown in 1827.

Calcification. The infiltration of animal tissues with salts of lime.

Cell. The elementary unit of organic structure. From the time of Schleiden and Schwann (1838) the researches of biologists have been greatly aided by the demonstra