- The Growth and Migration of Granules of the Cerebellum
Half a dozen nuclei of as yet undeveloped granules are seen lying beneath the pia mater. From this level to the bottom of the drawing granules are shown in successive stages of growth. These developing granules, selected from various preparations of the cortex of the cerebellum, were drawn from nature. - The Formation of an Image by the Refracting Media of the Eye
x, The common centre of curvature (nodal point of the several media). Rays which pass through this point are not deflected. y, The principal focus of the system. All rays which are parallel to the optic axis converge to this point. The image of the point A is formed at a, the spot at which a ray parallel with the optic axis meets an unbent ray—the image of B at b. - Sense-Organs susceptible to Pressure
All are formed on essentially the same plan; a fibrous capsule invests a group of epithelial cells amongst which a nerve ramifies. The simplest form is known as a Grandry’s corpuscle-a nerve ending in one or two plates between two or three epithelial cells. These organs are found in great numbers in the bills of aquatic birds. If a duck is watched whilst it is gobbling mud at the margin of a pond, it will be seen to have a remarkable capacity for discriminating between the shells of small snails, which it can crush, and stones, which it needs to drop from its bill. Its bill is also provided with small Pacinian corpuscles. - The External, Middle, and Internal Ear of the Left Side
From right to left, the figure shows the concha and lobule of the ear in profile; the external meatus (abbreviated); the drum, divided vertically, its posterior half visible; the hammer-bone, with the tip of its long arm attached to the drum, an arrow indicating the point of attachment and line of action of the tensor tympani muscle; the anvil attached by a ligament to the bony wall of the middle ear; the stirrup, with its foot-plate almost filling the oval window; the labyrinth, with the three semicircular canals above, and the scala vestibuli below. The curled black line shows the situation of the scala media, or ductus cochleæ (which contains the organ of Corti). Pulsations of sound which move the membrana tympani are transmitted by the three bones to the oval window. They shake the perilymph, producing waves which travel along the scala vestibuli to the apex of the cochlea, whence they return by the scala tympani to the round window (if they do not take a shorter course through the ductus cochleæ). The Eustachian tube opens out of the lower part of the middle ear. - The Diaphragm and Organs in Contact with it
The Diaphragm and Organs in Contact with it—A, in Expiration; B, at the End of a Deep Inspiration. Transverse Vertical Sections in the Line of the Armpit. A, At the end of an ordinary expiration the lung does not extend below the upper border of the eighth rib. From this level to the middle or lower border of the tenth rib the two layers of the pleura covering respectively the inner wall of the chest and the upper surface of the diaphragm are in contact. B, When the lung is distended with air it occupies the whole of the pleural cavity. - Biceps Muscle in Action
The power of muscle varies as its cross-section. For human muscles the maximum lift amounts to from 7 to 10 kilogrammes for each square centimetre. This is a large figure, but it must be remembered that, owing to the arrangement of the bones as levers, most muscles act at a great mechanical disadvantage. The greater the difference in distance from the fulcrum between the point of application of the force and the point of incidence of the weight, when the force acts nearer to the fulcrum than the weight, the greater is the mechanical disadvantage. The greater also is the rapidity with which the weight is lifted. What is lost in strength is gained in swiftness - Digestive system in humans
The stomach has been cut across a short distance from the pyloric valve, and removed, to show the viscera which lie behind it. The descending aorta and the vena cava rest upon the vertebral column. They are crossed by the pancreas and the transverse portion of the duodenum. The head of the pancreas is enclosed by the curvatures of the duodenum. The ducts of the liver and pancreas are seen entering the descending duodenum side by side. - A Section approximately at Right Angles to the Long Axis of the Heart
A Section approximately at Right Angles to the Long Axis of the Heart, exposing the Four Valves which lie very nearly in the Same Plane. The semilunar valve which guards the aperture of the pulmonary artery is the nearest to the breast-bone. - Red Blood-Corpuscles presenting, some the Surfaces, others the Edges, of their Discs, together with Single Representatives of Four Types of Leucocyte.
A, the most common type, highly amœboid and phagocytic. Its protoplasm is finely granular, its nucleus multipartite. B, a leucocyte closely similar to the last, but larger, and containing an undivided nucleus. It is shown with a cluster of particles of soot in its body-substance. C, a young leucocyte, or “lymphocyte.” D, a coarsely granular leucocyte. Its granules stain brightly with acid dyes—e.g., eosin or acid fuchsin. - A Minute Portion of the Pulp of the Spleen
A Minute Portion of the Pulp of the Spleen,very highly magnified. Stellate connective-tissue cells form spaces containing red blood-corpuscles and leucocytes. In the centre of the diagram is shown the mode of origin of a venule. It contains two phagocytes—the upper with a nucleus, two blood-corpuscles just ingested, and one partially digested in its body-substance; the lower with two blood-corpuscles.