Page:The American Cyclopædia (1879) Volume XV.djvu/696

 6G6 TETANUS appear from the egg in from six weeks to four months or more, are generally very different in form from the parents ; there is a hard tu- bercle on the snout of the young for breaking through the shell of the egg. The growth is very slow, and they attain the period of pu- berty the latest of all reptiles ; they can exist a long time without nourishment, and give signs of vitality, according to Kedi's experi- ments, 23 days after decapitation ; the same experimenter ascertained that a land tortoise lived for six months, blindly groping about, after the brain had been entirely removed ; they live more than a century. Chelonians first appeared in the oolitic period, according to Agassiz, when neither genuine birds nor mammals existed ; the so-called tortoise foot- prints in the new red sandstone and Devonian strata were undoubtedly made by crustaceans or other articulates; according to Pictet, im- pressions of their shields first occur in the Jura limestone and the Stonesfield oolite, and the four types of Dum6ril and Bibron together ; they also are found in the tertiary and diluvial deposits. In the diluvium of the Sivalik hills of the Himalaya range have been found the remains of a gigantic chelonian (colossochelys atlas, Cautl. and Falc.), which must have been 18 to 20 ft. in length ; it appears that its exis- tence was known to the natives, as this figure enters largely into the old East Indian cosmog- onies. In geological times chelonians existed in northern regions of Europe and Asia, now too cold for them; marine and fresh-water species also are often found together, a fact explained by estuary deposits, a more uniform constitution of the early waters of the globe, and a mixture by sudden inundations and sur- face changes. The present geographical range of chelonians is less extensive than that of the other orders of reptiles, the marine turtles hav- ing the greatest and the terrestrial species the least; the marine species are also the largest except the Galapagos tortoise. TETANUS, a spasmodic disease characterized by painful, involuntary, and protracted con- traction of a greater or smaller number of the voluntary muscles. As seen in temperate cli- mates, the disease is almost invariably con- sequent upon a wound or injury ; but in par- ticular localities and in hot climates, it may occur without any lesion either external or internal. The disease usually begins with chills and a feeling of depression and debility, with vertigo and sleeplessness. At first there is commonly a feeling of stiffness and uneasiness about the muscles of the neck and jaws. The patient thinks he has taken cold or has a slight rheumatic affection. He finds he is unable to separate the jaws to any distance, and more or less gradually they close, so that he is unable to open the mouth at all; a condition called locked jaw. As the disease advances there is aeute pain at the bottom of the stomach, ex- tending through toward the back; and this pain, like the contractions of the voluntary muscles, is aggravated in paroxysms. Grad- ually the large muscles of the trunk and ex- tremities become affected. In some cases all the muscles are firmly contracted, and the body remains stiff and straight. Ordinarily the strong extensors of the trunk and limbs are more af- fected than the flexor muscles, or their supe- rior power overcomes the resistance of these latter, and during the paroxysm the body is forcibly curved backward, the patient resting upon his hands and heels only. This consti- tutes opisthotonos. Occasionally, though it must be very rarely, the body is bent forward, constituting emprosthotonos ; and still more rarely there is lateral curvature, forming pleu- rostkotonos. The muscles concerned in deglu- tition are early affected, so that swallowing is rendered difficult or impossible. Later, spasms of the muscles of the face occur, the brow be- coming knit, the eyes wide open, fixed and staring, the nostrils distended, and the angles of the mouth drawn back, exposing the clenched teeth, and producing an expression called risus sardonicus. When the disease has once set in, the muscles affected are rarely at any time afterward wholly relaxed. At intervals more or less closely approximated to each other ac- cording to the severity of the disease, paroxysms occur during which the spasm is aggravated, the muscles affected becoming tense and hard as boards. During these paroxysms the pa- tient commonly suffers from intense pain in the muscles affected, and the substernal pain, dependent probably on spasm of the diaphragm, is likewise aggravated. Cases have occurred in which the teeth have been broken, bones fractured, or muscles torn across. The spasms come on even when the patient is perfectly at rest ; but they are evidently excited by the slightest attempt at voluntary motion, by ef- forts at deglutition, or by mental emotion. The patient's mind is commonly unaffected throughout the disease ; the bowels are apt to b^ obstinately constipated, and when evacua- tions are obtained they are offensive and un- natural. Death may occur either suddenly during a paroxysm or from suffocation, the muscles of respiration becoming fixed and the spasm in some instances probably affecting the glottis. In other cases death results from ex- haustion, the patient being worn out by pain, sleeplessness, and want of nourishment. Te- tanus is fatal in the large majority of cases. Post-mortem examination throws but little light on its pathology. Dr. Lockhart Clark believes that degeneration of the cells of the spinal cord is always present ; but the fact that the symptoms are so similar to those of poi- soning by strychnia would lead to the opinion that the cause of the disease is in a morbid condition of the blood, although the medulla oblongata and spinal cord are the parts attacked. In cases arising from wounds, the nerve lead- ing from the wound shows evidences of in- flammation, being commonly red and swollen ; but with this exception no lesions have been