Part 20

During this period, Dr. Oleson’s study shows there were two 5-year peaks in rabies, from 1911 to 1915, inclusive, and from 1926 to 1930. During the first period the annual average of bites diagnosed as made by rabies-infected animals was 233, compared with only an average of 78 for the previous three years for which records were available. There followed a period of 10 years during which the number of rabies cases diagnosed in biting dogs averaged only 43 a year. Starting with 1926 the curve leaped up again and in the next five years there was an average of 288 cases a year. Then came another rapid decline.

Apparently the number of rabies cases has no relation to the number of bites. These remained practically stationary at an average of about 3,500 from 1908 to 1926. There was a sudden jump to more than 7,000 cases in 1925, just before the start of the second rabies peak. But since 1930 the number of bites reported has continued to go up, in the face of rigid muzzling restrictions, until it has reached the alarming figure of 20,000. At the same time the number of rabies cases rapidly has gone down.

The same tendency toward the mad dog cycle has been noted in several European countries. It may be due to an inexplicable waxing and waning of the virulency of the rabies virus. During the peak years extraordinary efforts were made to impound all unlicensed dogs, and the decline of the waves may have been due to the lessening of the number of potential rabies carriers by this means.

Contrary to general belief, dogs are getting better tempered rapidly during dog days. The high peak of the year in bites is reached about the middle of June. Then comes a very sharp drop, which continues steadily as colder weather comes on.

No breed of dogs is entirely free from the biting tendency, but some are much more prone to it than others. The mongrel doesn’t rank among the really vicious dogs and pedigree counts for nothing. The 10 breeds, in the order of frequency of their reported bites, are: German police, chow, poodle, Italian bull, fox terrier, crossed chow, airedale, pekingese and crossed German police dog.

_The Amazing Survival of the Opossum_

The opossum, sole survivor in the New World of a primitive and very ancient family, represents an overlooked principle in evolution—survival by endurance.

How this clumsy, persecuted animal has endured through millions of generations in the midst of savage and hungry foes is the subject of a revealing study by Dr. J. D. Black of the University of Kansas.

Dr. Black examined closely the skeletons of 95 opossums in the university museum—all killed in the immediate vicinity. Thirty-nine of them gave evidence of broken bones that had completely healed. One specimen had suffered, and recovered from, breaks of both scapulae, 11 ribs, two broken in three places, and a badly injured spine. Still another gave evidence of having suffered at the same time fractures of the jaw, the scapulae, and nine ribs. Many showed evidence of ribs and scapulae broken in several places. The ability to survive such severe injuries—they would be fatal in any other animal either in themselves or because the crippled condition resulting from them would make a creature an easy prey to its enemies—illustrates the importance of the opossum’s practice of playing dead.

The opossum represents an important stage in the evolution of mammals—that of the marsupials, or pouch bearers. They presumably were quite widely distributed over the earth at one time, before the emergence of the placental type of mammals to which the human race belongs, together with almost all other warm-blooded animals. They may be the ancestors of the placentals or they may represent a different line of development from the ancestral reptiles. In any event, they are considerably nearer the type of those ancient egg-laying reptiles. They are just a step beyond the egg-laying stage.

When the placentals arose the marsupials quickly disappeared from most of the earth. They were not so well adapted for survival in conflict with the more advanced, efficient type of animal. Only in Australia did they find a haven. With a single exception, they were the only mammals there when the continent first was discovered by white men. This has led to the speculation that Australia was cut off from the rest of the world before the placental races were evolved, or before they had attained such efficiency in the ways of life as to enable them to survive. There the marsupials, without competition, were able to survive and differentiate into rich fauna of the continent—of which the kangaroos are considered the most characteristic animals.

The one exception was in North and South America in the person of the lowly opossum. All the meat-eating animals which arose around the creature fed upon it if they could catch it. It was not very efficient in getting away from a pursuer. It developed no effective armor, like the shell of the armadillo or the quills of the porcupine, with which other weak animals managed to survive. It was not even very efficient at hiding. When man arrived on the scene with his bows and his guns, its last havens, the treetops, lost their small measure of security.

All the cards were stacked against the survival of the opossum, but it developed a means of its own to keep a tenacious hold on life while far more efficient creatures—beset with new enemies and changing climates—were forced to give up. The great mammoth herds, lords of the earth for a million years, disappeared. The ferocious saber-tooth tiger and the great cave bear expired by the roadside in the race of evolution. But the poor opossum had discovered the important principle that the meek shall inherit the earth—or, at least, be allowed to live in it. It became the great pain endurer and lived by submitting and gritting its teeth. It didn’t fight nor hide. It merely suffered and learned how to endure suffering. This supreme ability of the opossum to recover from injuries goes a long way toward explaining its survival.

The opossum thus appears to be the prototype of a familiar class of men and women. They are frequently encountered. As children they have almost every conceivable disease. Their adolescence is a continuous succession of broken bones. Their parents despair of raising them. When they come to adult life the story is much the same. They suffer a constant stream of misfortunes, physical and otherwise. Physicians are amazed at their recoveries. And they often survive into the 80s and 90s of life while the healthy, fortunate individuals with whom they started out are left behind in the prime of life—victims of pneumonia, heart disease or accident. When the latter die the news comes as a surprise to their acquaintances who cannot understand how the strong die and the weak survive. They ponder over the paradox that strength is weakness and weakness strength. The ancient opossum might explain that paradox if it had the means to express itself.

_Mammal Prototypes of the “Mermaid”_

The prototypes of the “mermaids” of legend are among the least known of all animals to naturalists because of their underwater habitat and their secretive habits. They are the manatees of the Caribbean region and the dugongs of the Indian Ocean. They constitute the only remaining species of the serenia, or moon creatures, distant relatives of the elephant. Both have a somewhat human facial appearance. They feed standing upright in the water, their flippers held out before them like arms. Sometimes the females hold their calves in these flippers. Seen from a distance, they have a curiously human appearance, which may account for the many reports of mermaids and mermen.

This is especially true of the dugong—a creature of the open sea, with a white, almost hairless body. It is extremely secretive and has almost never been captured alive. When one is washed ashore or caught in a fisher’s net it causes superstitious fear among the natives. The manatees are not so human in appearance and are much better known.

The creatures seldom make their appearance above water in daylight. They prefer to gaze in the moonlight, and this has added to their humanlike appearance which has given rise to the mermaid legends.

One of the few persons to study the animal at close range, O. W. Barrett, an American explorer, tells us the following concerning the manatee:

“The animal still is fairly common in most fresh-water bayous, lagoons and rivers along the east coast of Nicaragua. One of the best-known herds on the Caribbean Coast inhabits the Indio River, just north of Greytown, Nicaragua. Estimates of its number vary from a few score to several hundred. The herd apparently is stationary there and does not increase or decrease to any notable degree from year to year, although the natives take a heavy toll....

“A manatee can remain under water from 20 to 30 minutes when frightened. During the daytime the slightest unusual noise, like rain falling on a tin pail or the spitting of the hunter, is sufficient to keep the whole herd submerged for hours, yet while they are grazing the hunter may go up and slap them on the back unnoticed.

“Families consisting of a bull, a cow, and one or two calves usually ... merge into a herd of from 10 to 50 or more individuals living in a certain stretch of river, concentrating during the day and scattering at night. They generally graze at night, although a few individuals may be seen feeding in broad daylight. The body is held nearly vertical while grazing. The head is held well out of water, while the armlike flippers poke the grass toward the mouth. The noise made by the flapping of the huge upper lip and the crunching of the large teeth can be heard distinctly 200 yards or more away. The sound is much like that of horses grazing in a pasture. Adult manatees appear to average somewhere between 8 and 10 feet in length. Some—old females, presumably—may reach 12 feet.”

A much more seclusive animal is the true “mermaid” of legend—the dugong of the open ocean. Unlike the manatee, it is a creature of the sea and seldom ventures into the fresh-water rivers and lagoons. Few naturalists ever have actually seen one of the creatures. Mr. Barrett’s first acquaintance with the creature came in Mozambique, Portuguese East Africa, when some native fishermen caught in their net what they described as a “white porpoise.” They were terrified and gladly presented their catch to an Italian blacksmith. This man crudely embalmed the animal, placed it in a rough coffin and freighted it to Johannesburg, where he rented a show room and made a fortune exhibiting “the only genuine mermaid—half fish, half human.”

For many years mariners in the Indian Ocean and the Red Sea have told of seeing objects resembling women standing waist high on the surface. Zoologists of the Middle Ages described a “bishop fish” which had been seen standing with outstretched arms, supposedly blessing the waters. In nearly every case, it seems likely, the objects were strange water animals—the dugongs. They have a curious resemblance to human beings, especially naked women, when seen from a distance.

Nearly all mermaid stories have originated in water where dugongs are abundant. Spanish and Portuguese sailors, the first Europeans to encounter the animal, called it the “woman fish.” The creature is best known to Malagasy fishermen of Madagascar who, while they prize its flesh highly, attribute to it human qualities and affinities. After capturing one the fisherman must perform various religious rites and before he is allowed to sell the flesh at a public market he must take an oath that there have been no unnatural relations between himself and his mermaid victim.

The female’s breasts are roughly in about the position of those of women. She has the habit of rising about halfway out of the water and sometimes has been described as holding her baby in her flippers. Little is known of the life history and habits of the dugong. It is a creature of the shallow sea which never has survived long in captivity. It seems to share with the elephant and with man the faculty of shedding tears when it is in trouble or pain. One which was kept for several months in the Colombo zoo in Ceylon constantly was weeping. Malagasy fishermen used to torture the animals in order to collect the tears, which they sold as love charms.

Another extant member of the “mermaid” family is the manatee, found on both sides of the Atlantic in the warm, fresh water rivers of Africa and South America. Although never mistaken for a human, it is accorded considerable superstitious regard. The Kalaboi of Nigeria regard it as a sacred animal and the incarnation of a human soul. If a fisherman kills one, by accident or otherwise, he must undergo an elaborate cleansing ceremony which involves offerings before images of his ancestors and remaining indoors for three days. During this period he is rubbed from head to foot with a yellow pigment by women of his family. While the purgative rites are in progress the women sing at dawn and dusk. On the third day there is a feast on the meat, but a bit must be given to every household in the village to lay upon the shrines of ancestors.

Both manatee and dugong, and formerly the extinct sea cow of Bering Sea, are probably the closest living relatives of the elephant. They have similar brain and heart structure. The molar teeth of the mermaid family are like those of early elephants. The male dugong has tusks. There also is a great extension of the upper lip which overlaps the side of the mouth—a start in the direction of a trunk.

The next nearest relatives of the elephants are the hyraces, or conies, of Africa and Syria, best known in the form of expensive fur coats. They look and act like rabbits. A Hebrew prophet made them symbolic of timidity. Only a taxonomist would suspect these little creatures could claim any kinship to the largest of land mammals.

_Limbless Lizards and Glass Snakes_

A supposedly welcome guest in the underground chambers of leaf cutter ants is the amphisbaena, a nearly limbless lizard about a foot long which looks somewhat like a gigantic earth worm. These creatures, seldom seen, can be found from Brazil north to lower California and there is one isolated species in Florida.

“Those brought to me,” observed the noted British naturalist and explorer of Brazil, Henry Walter Bates, “were generally not much more than a foot in length. They are of cylindrical shape having, properly speaking, no neck, and the blunt tail which is only about an inch in length is of the same shape as the head. This peculiar form, added to their habit of wriggling backwards as well as forwards, has given rise to the fable that they have two heads, one at each extremity. They are extremely sluggish in their motions, and are clothed with scales that have the form of small imbedded plates arranged in rings around the body. The eye is so small as to be scarcely perceptible.

“They live habitually in the subterranean chamber of the Sauba ant; only coming out of their abodes occasionally in the night-time. The natives call the amphisbaena the “mai das Saubas,” or mother of Saubas, and believe it to be poisonous, although it is perfectly harmless. They say the ants treat it with great affection and that if the “snake” be taken away from the nest the ants also will forsake it. I believe, however, that they feed on the saubas, for I once found remains of the ants in the stomach of one of them.

“Their motions are quite peculiar. The undilatable jaws, small eyes and curious plated integument distinguish them from other snakes. These properties evidently have some relation to their residence in the subterranean abodes.”

Closely related is the Florida worm lizard, rose-colored and completely legless and earless. It is about a foot long and looks so much like an earthworm that expert collectors have been fooled. A peculiarity is that it always goes down into a burrow tail first.

The Arizona worm lizard, a somewhat fabulous animal of the same family, is not, so far as is known, represented in any collection. One veteran miner told of dragging “a purple snake with two legs on its neck” from the gravel. A woman claimed to have kept as a pet for three months “a purple snake with its legs where its ears ought to be.”

All these animals are in the same general family as the glass snakes of Europe and the United States. These are long, slender, legless lizards. They are burrowing animals which occasionally are turned up by ploughmen, but they often come to the surface voluntarily at night. Specimens occasionally found in daylight usually are hiding in dark recesses.

Each animal consists of apparently quite separate parts, body and tail. The body is from six inches to a foot long, according to species, and the tail may be twice as long. The animal can disengage its tail by a single twist when caught by that organ. The slightest injury or rough handling causes this tail to fly to pieces. Each piece wriggles energetically, supposedly to attract attention while the lizard itself crawls to safety in its burrow. The body does not break up and does not, as popularly reputed, come back later to gather up fragments of its tail. Instead it grows a new tail, always smaller than the original, from the stump.

_The Only Bug in the Sea_

Only one group of insects has taken to the sea—the small, gray long-legged water striders. Unlike fresh water relatives of the same genus, these have permanently lost their wings. They have no further use for this means of movement in the ocean.

Great numbers have been found floating and swimming in the open sea around Pacific islands. Both nymphs and adults sometimes are blown onto the beaches by strong winds. They are awkward on land, seek shelter in any depression in the sand, and fall easy prey to birds and the multitude of ghost crabs which glide over the sands after dark.

On the surface of shallow water the insects are found in groups of hundreds of thousands. Apparently they feed on plankton which rises to the surface at night. They themselves are not eaten by fish. This is probably due to scent glands which secrete a strong odor which is repellant to the ever hungry vertebrates.

In small embayments are found enormous numbers of one type of water strider, the female of which is less than a twelfth of an inch long. The male is considerably smaller and rides on the back of his mate to ensure that the two will not be separated by wind or tide.

Insects are by far the most abundant of all land animals; the reasons why only one genus has invaded the sea have been the subject of much speculation. On the continents, insects are found in salt water lakes where the saline concentration is much greater than in sea water. Other types live in torrential streams and waterfalls where they get much rougher treatment than would come from wave action. There are two probable reasons for the failure to invade the ocean. One is the fact that no insect ever has been able to live in very deep water. The “bug” race has evolved a special breathing mechanism admirably suited to life on land but rather poorly adapted to life under water. Besides, the seas have been taken over almost completely by the remote relatives of the insects, the crustaceans. These include, besides crabs and shrimps, the superabundant copepods, the “lice of the ocean.” Invaders from the land never have been able to compete with them.

_A Crocodile With Life After Death_

There is an animal that can bite—it might even slash off a man’s arm—after it is dead. Alive it is relatively inoffensive. Being killed makes it positively mad.

Its uncanny ability to bite half an hour or more after its neck has been broken is a major risk for followers of one of the most adventurous of professions—the jungle crocodile hunters. Their story is a saga paralleling that of the Antarctic whalers who first told of Moby Dick. One of the most expert of them is Dr. Fred Medem, Smithsonian collaborator and professor of zoology at the University of Bogota. He has twice been bitten painfully by “dead” reptiles.

The animal is the caiman, smaller than either alligator or crocodile and probably more closely related to the former. Its hide, like that of its two fellow crocodillians, is valuable for leather and during the past few years it has been pursued close to extinction by professional hunters in Colombian and Brazilian jungles and lagoons. Dr. Medem is an eminent zoologist. He doesn’t believe, of course, that any animal that is completely dead can bite off a man’s arm, but he is hard put to explain what he himself has experienced. He thinks that part of the caiman’s nervous system which activates its snout and mouth is somehow disconnected from the rest and does not die at the same time. Thus the dead reptile has no consciousness when it bites. It is a reflex action of one small segment of the nervous system that somehow is not completely dead.

There is only one way to be safe for an indefinite period after the caiman is killed. That is to chop a hole in its neck and run a pointed stick into the medulla oblongata, the reflex action center at the base of the brain. When this is destroyed the ability to bite is lost. One can proceed to skin the animal without fear of losing an arm or a finger. Ordinarily this reptile will not attack a human. It lives on smaller animals—wild and domestic pigs and the pig-like capybaras—that venture into the jungle rivers.

Dr. Medem has recently discovered a curious new sub-species of caimans confined, so far as known, to the upper reaches of the Apaporis river, a tributary of the Amazon. It is much more crocodile-like in appearance than the rest of the family, with a very long, narrow snout. The others have broad, flat snouts. It retains prominent bony ridges over its eyes—one of the most striking characteristics that distinguish the caimans from both crocodiles and alligators.

A much more dangerous animal is the Orinoco crocodile, a large reptile which lives only in the Orinoco and its tributaries and has a taste for human flesh. The creature is especially dangerous to bathers and to women doing their washing in the rivers. This is one of the two species of these dreaded reptiles known in South America. The other is a smaller, less aggressive creature of seashore rivers and lagoons. The inland species now is quite close to extermination. Until recently it was pursued by both German and French companies of professional crocodile hunters. Now they have given up because the profits have become too small for the risk.