ANIMAL . ANIMALCULES 513 Spallanzani states that two swallows flew from Milan to Pavia, 18 miles, in 13 min- utes. The precision and rapidity of muscu- lar action of some animals is also remark- able. The elephant can pick up a pin with its huge trunk. The chamois goat leaps with the greatest precision from point to point on the mountain rocks, alighting on surfaces scarcely large enough for its feet to rest upon. A bird called the wryneck, having a long tongue like the woodpecker, darts forth and retracts this organ with such rapidity that the eye is unable to follow it. The frog also catches flies by move- ments scarcely less rapid. No animal possesses more than five senses, and some are probably endowed with not more than one, the sense of touch. But we find each sense manifested in the animal scale, in all grades of perfection. Of in- telligence, also, we find great varieties in birds and mammalia, while below the former we hard- ly find any higher attributes than mere instinct. This, indeed, predominates in most birds, and in the mammalia often assumes the appearance of cunning, artifice, or sagacity. The Egyptian ichneumon, being fond of poultry, feigns it- self dead till the birds come within its reach, when it springs upon and strangles them, usu- ally contenting itself with sucking their blood. There is a species of musk which also feigns death when caught in the noose set for it, but escapes the moment it is untied. The Europe- an cuckoo neither builds a nest for itself nor hatches its own eggs. It deposits a single egg in the nest of the hedge sparrow (and some- times of the wagtail or the titlark), while the other bird is laying her eggs. This addition to her charge disturbs her arrangements, and during incubation she throws out her own eggs, or so disturbs as to addle them, to make room for the cuckoo's ; but, according to Dr. Jenner's observations, she never displaces the latter. When some of her own eggs and that of the cuckoo are hatched, the young cuckoo manages to throw out the young sparrows and the remaining eggs, and thus gets the whole nest to itself. The ostrich surrounds her nest with a trench, in which she deposits some of her eggs as the first food of the young ones to be hatched from the eggs in the nest. To an animal capable of being educated, though to a slight extent, we cannot deny the possession of intelligence ; and judged by this criterion, most of the mammals and some birds must be re- garded as possessing this attribute. The adap- tation of means to ends, in entirely new cir- cumstances, must also generally be attributed to it rather than to mere instinct. Swallows club together to repel a common enemy, many closing round a hawk. A martin being caught in a noose of packthread, fastened at the other end to a gutter, all the martins in the vicinity were attracted by its cries, and, striking the thread with their bills, succeeded in setting him at liberty. The superior intelligence of the elephant is often asserted ; but this animal is really less intelligent than the dog, and about 34 VOL. i. 34 equal hi this respect to the horse. As tested by educability, as well as by acquired tastes, the quadrumana are far the most intelligent of the lower animals. Carnivorous animals are mostly solitary in their habits, while many of the herbivorous are socially inclined and gre- garious. This is the case with the llama and the horse in the wild state. Camelopards herd together usually in companies of 16. Ante- lopes are found in herds of 2,000 or 3,000, or in small parties of only five or six individuals. The males also of antelopes and deer frequently consort together, independently of the females. On the other hand, the conjugal attachment of the stellerine (allied to the dugong) is so great that if the female be taken, the male will dash on shore to her in spite of blows, with the swiftness of an arrow. Some animals are do- cile and yielding, others obstinate. The mule is proverbial for the last attribute, but the llama is still more remarkable in this respect. Some animals are grave or morose, while others are playful, and even have their peculiar amuse- ments. The mocking-bird amuses itself in frightening other small birds by imitating the screams of the sparrow hawk. The particular classes and orders of animals will be described under the appropriate heads ; the four classes of the vertebrata forming the articles AMPHI- BIA, HERPETOLOGY, ICHTHYOLOGY, MAMMALIA, and OBNITHOLOGY ; while the invertebrata will be found described under the heads ANIMAL- CULES, ABAOHNIDA, ARTICULATA, CRUSTACEA, EOHINODERMA, ENTOMOLOGY, ENTOZOA, EPIZOA, MOLLUSOA, PROTOZOA, and KADIATA. ANIMALCULES, a name familiarly applied to the more minute forms of animal life, for the. knowledge of which we are mainly indebted to the microscope. Leeuwenhoek led the way in this as in most other branches of microscop- ic study ; but it is to Gleichen that we are in- debted for the first attempt at the systematic study of the subject. He was followed by the Danish microscopist O. F. Muller, who made the first regular classification of animal- cules. Subsequent observation has detected many errors in the classification of Muller, and it has now little other than a historic in- terest. It is to Ehrenberg that we are indebted, directly or indirectly, for almost all our knowl- edge of these forms. Since the appearance of his work, Die Infwionsthierchen, the study of minute animal forms has been ably pursued by Dujardin in France, Siebold, Kolliker, and others in Germany, Owen in England, and Bai-. ley in the United States. The earlier observ- ers grouped together, under the term animal- cules, a vast variety of living beings having nothing in common except their minuteness of size. Plants and animals, mollusks, crus- taceans, insects and worms, larvae and per- fect forms, all were aggregated together under the vague term animalcules. The labors of modern scientific men have been in great part exhausted in the distribution of this mass of animal and vegetable life among the various
