doubts that in large quantities they act injuriously upon the system. Alcohol deranges the action of the muscles by its influence upon the nervous system, causing defective regulation of the supply of nervous force to the several muscles. As to whether it is possible to use alcohol in small amounts without impairing the perfection and vigor of muscular action, there is one very significant fact: that men in training for severe muscular exertion in athletic contests are strictly forbidden the use of alcohol in any form and in any quantity, whether or not they have been previously accustomed to such indulgence. As the rules for such training are the result of long and wide experience and most careful study, it is safe to conclude that alcohol at least does not promote strength, endurance, or precision of muscular movement." -MACY, Physiology.

Effect of Tobacco on Muscles. The stunting effect of tobacco on the growth and development of the muscles is well known. Every teacher of gymnastics knows this; hence tobacco is not allowed to the athlete. Another reason why the man in training is not allowed tobacco, is because of its paralyzing effect upon the nerve cells controlling the movement of muscles, this diminishing or inhibiting the nervous energy which a man uses in the exercise of his muscles.

"Tobacco and other narcotics also affect muscular activity through their effect upon the nerves. All narcotics have as their natural, characteristic influence the paralyzing of some of the nerve centers. As medicines they may give relief from pain and so act beneficently under skillful application. Tobacco has a special effect upon the nerve centers regulating the action of the muscles of the heart, making that action irregular and less vigorThis is particularly true of the young, and it is not very uncommon for boys addicted to excessive cigarette smoking to develop serious disease of the heart, or even to die suddenly from 'heart failure.'"-MACY, Physiology.

ous.

a framework to which muscles are attached; thus they are used as levers for purposes of movement. Second, they give protection

they form a case

around the brain, and

spinal cord; as ribs

they protect the or

gans in the body cavity. Third, they give rigidity and form to the body.

Laboratory Work on the Skeleton of a Frog; Comparison with the Skeleton of Man. - For this purpose, clean skeletons of the frog (these may be prepared by careful students) and a prepared skeleton of man may be used. This exercise may be made of increased value by using skeletons of several different vertebrates, for example, a bony fish, frog, snake, bird, dog or cat, and man. The different re

Skeleton of the frog; S., skull; SC., scapula; R.U., radio ulna; H., humerus; Ph., phalanges; MC., metacarpals; C., carpals; V., vertebral column; UR., urostyle; P.G., pelvic girdle; F., femur; TF., tibia and fibula; TS., tarsals; MT., metatarsals.

gions may be identified and homologies and analogies drawn between different bones and organs in the various skeletons.

The skeleton of vertebrate animals consists of two distinct regions: a vertebral column or backbone which, with the skull, forms the axial skeleton; and the parts attached to this main axis, the appendicular skeleton (the appendages). All skeletons of vertebrates have the same general regions, the size and shape of the bones in these regions differing somewhat in each kind of animal.

In the axial skeleton of the frog, as well as in man, the vertebral column is made up of a number of bones of irregular shape, which fit more or less closely into each other. These bones are called vertebra. Notice that the

Skeleton of man; CR., cranium; CL., clavicle; ST., sternum; SC., scapula; H., humerus; V.C., vertebral column; R., radius and ulna; P., pelvic girdle; C., carpals; MC., metacarpals; Ph., phalanges; F., femur; Fi., fibula; T. tibia; Tar., tarsals; MT., metatarsals.

vertebræ possess long processes to which muscles of the back are attached. Compare the vertebral column of the frog and man in the following respects: Is there a distinct neck region? Are ribs present? Are the ribs attached to the vertebræ? How many vertebra in man bear ribs? In man a flat bone to which certain of the ribs are attached is found on the ventral midline of the skeleton. This bone, called the sternum, is so small in the frog that you will not be able to see it. Are all the ribs in man attached to the breastbone or sternum? How many ribs are free from the breastbone? Notice, in the frog, the peculiar long bone at the posterior end of the spinal column; this bone is called the urostyle. No homologous bone is found in man. Look at the vertebral column of man; notice that it is shaped somewhat like the letter S. The bodies of the vertebræ, piled one upon the other, form a column of enough strength to support the whole body. The double curve of the vertebral column combines elasticity with strength.

Structure of a Vertebra in Man.Observe a single vertebra of man; it will be found, in a general way, to consist of two regions, a solid rounded portion called the centrum or body, and a bony arch from which are given off the processes referred to above. Within this arch (called the neural arch) is found the spinal column or nerve cord. Thus, the vertebræ form a wonderful protection for this most delicate of all organs; and, with the bony covering of the skull, protect the central nervous system.

Adaptations in the Vertebral Column. The vertebral column in man is made up of many separate pieces of bone: thirty-three in a child; twenty-six in the adult, several bones in the region of the pelvis later growing together. Each vertebra presents the general form of a body or centrum of bone and a bony arch with seven projections; in this arch runs

the spinal cord. The surface of the centrum and those parts of the vertebræ each of which fits into its next neighbor are covered with pads of cartilage. Two of the processes in each vertebra project forward and two backward; these form articulations or joints with the neighboring vertebræ. Of the other processes, one projects dorsally and two project laterally; these give attachment to the muscles of the back. The two vertebræ directly beneath the head are modified so as to permit the skull to rest in the upper one; this articulates freely with the second vertebra, thus permitting of the nodding and turning movements of the head. Besides these individual adaptations, the vertebral column, as a whole, is peculiarly adapted to pro

tect the brain from jar; this is seen in the double bend of the vertebral column and the pads of cartilage between the individual vertebræ. The whole column of vertebræ joined each to the other supports the weight of the body. The largest vertebræ

at the base are joined to the huge Vertebra, showing attachment of pelvic bones for the better support

of the body above. That part of the vertebral column of man which bears the ribs is known as the thoracic region. The ribs, twelve in number, are long bones which combine lightness with strength; joined by elastic cartilage to the sternum in front and to the vertebræ behind, they form a wonderful protection to the organs in the thoracic cavity and yet allow free movement in breathing. That part of the skeleton. to which the bones of the anterior and posterior appendages are attached are respectively known as the pectoral girdle (from which hangs the arm) and the pelvic girdle (which joins the leg bones to the axial skeleton).

The Appendages. The bones of the appendages attached to the pectoral and pelvic girdles are adapted peculiarly to locomotion and support; for this purpose the bones are long and strong, hinged by very flexible joints. The latter are especially free in the hand to allow for grasping. In the leg, where weight must be

vertebræ possess long processes to whic muscles of the back are attached Compare the vertebral column of the frog and man in the following respects Is there a distinct neck region? A ribs present? Are the ribs attached to the vertebræ? How many vertebr in man bear ribs? In man a flat bort to which certain of the ribs are attached is found on the ventral midline of the skeleton. This bone, called the sternum, is so small in the frog that you will not be able to see it. Are all the. ribs in man attached to the breastbone or sternum? How many ribs are free from the breastbone? Notice, in the frog, the peculiar long bone at the pos terior end of the spinal column; this bone is called the urostyle. No homologous bone is found in man. Look at the vertebral column of man; notice that it is shaped somewhat like the letter S. The bodies of the vertebra, piled one upon the other, form a col umn of enough strength to support the whole body. The double curve of the vertebral column combines elasticity with strength.

Skeleton of man; CR., cranium; CL., clavicle; ST., sternum; SC., scapula; H., humerus; V.C., vertebral column; R., radius and ulna; P., pelvic girdle; C., carpals; MC., metacarpals; Ph., phalanges; F., femur; Fi., fibula; T. tibia; Tar., tarsals; MT., metatarsals.

1

Structure of a Vertebra in Man.Observe a single vertebra of man; it i will be found, in a general way, to consist of two regions, a solid rounded portion called the centrum or body, and a bony arch from which are given off the processes referred to above. Within this arch (called the neural arch) is found the spinal column or nerve cord. Thus, the vertebræ form a wonderful protection for this most delicate of all organs; and, with the bony covering of the skull, protect the central nervous system.

Adaptations in the Vertebral Column. The vertebral column in man is made up of many separate pieces of bone: thirty-three in a child; twenty-six in the adult, several bones in the region of the pelvis later growing together. Each vertebra presents the general form of a body or centrum of bone and a bony arch with seven projections; in this arch runs