out by quotations from the two books in "deadly parallel" columns.
One of the more interesting of Wythe's original observations in the microscopic field was published in "The Medical Examiner and Record of Medical Science," of Philadelphia, in 1851. It has reference to the movement of the blood in the capillaries brought about by the constriction of the arterial walls, and can best be told in his own words: "The microscopic observations to which we are about to refer leads the writer of this article to entertain a different view (than Carpenter's idea of distention by the blood, etc.). It seems to be demonstrated by this that the pulsatory movement is a property residing in the arterial coats themselves, independent alike of the heart's action and the stimulus of the blood.
Having caught a mouse in a trap, (it was quite cold and stiff when taken out) I was desirous of making some preparations of epithelium, etc. On taking out the kidneys it occurred to me to place a thin slice upon a slide for microscopic examination. The slide was made quite through the middle of the kidney, and was about one-thirtieth of an inch in thickness, just thick enough to be translucent. On placing it under the microscope one of the largest vessels was observed in active motion, alternately contracting and dilating, with evident vermicular contractions, communicating motion to the blood corpuscles in the capillaries for a considerable distance. The movement seemed limited to the artery and was not communicated to the coats of the capillaries, although their contents had an oscillatory motion corresponding to the contents of the artery. The phenomenon was seen for about three hours, when the observation was suspended. The motion had been considerably diminished, both in extent and energy.
I was at first inclined to attribute this activity to evaporation of the watery particles from the slide, but
