LITERARY AND SCIENTIFIC. 369 



arrive at last at the complex structure displayed by the mammalia and man. The 

 Infusorial animals were the first that arrested attention, and were found in fluids, 

 under certain circumstances, in every part of the globe, and partook of the motion 

 of the fluids they inhabited. Some of these were extremely simple ; but many 

 others, as shown by Professor Ehrenbcrg, were much more complicated, some 

 possessing an outer shell, others provided with tentacula or arms, and others again 

 exhibiting a regular apparatus of stomach and intestines. 



Proceeding to the polype tribes, including the coral animals, the lecturer ob- 

 served, that the animal kingdom had been formerly defrauded, for Toumefort had 

 classed them with vegetables ; but later observations had incontestibly proved that 

 the coral reefs, which so obstructed navigation in the Pacific, and many of 

 which rose above the ocean, yet advanced from such profound depths beneath, were 

 the sole work of innumerable polypes, who framed their habitations in a similar 

 manner to what we observed in the snail, who secreted his shell. Some of the 

 polypi, although they had a separate existence, yet lived in common, and the nutri- 

 ment imbibed by one was conveyed to all. According to the experiments made by 

 Blumenbach, if a hydra be divided into several portions, each of these will, in a 

 few days, become a perfect animal. By dividing either the head or posterior part 

 of the animal longtiiudinally, the number of these parts maybe increased at plea- 

 sure. They may be turned inside out like a glove, a manoeuvre which requires 

 considerable dexterity and practice. They may be divided longtitudinally, and 

 expanded like a riband, and in this state, as remarked by llosel, they have the 

 wonderful power of running together, so that two or more join to become one 

 individual. The sea anemonies were another curious tribe, that expanded their 

 tentacula after the manner of the petals of flowers, and though fixed to the rocks, 

 had yet the power of removing, when (if he might so express himself) they thought 

 fit. The Crustacea shewed a farther advancement in organic structure, their soft 

 internal bodies being defended and preserved by a coriaceous covering or shell, as 

 the crab and lobster. These still possess the property of reproducing any limb, of 

 which time or accident might have deprived them, and specimens were now before 

 them in which the various gradations were perceptible, from the newly-emerging 

 limb to the claw fully and completely formed. Next these followed the insect 

 tribes, possessing ganglia and displaying muscular action, but still without internal 

 bones. 



The next department was that of the molluscous animals. Here we first find a true 

 heart differing from that of the articulata in possessing two cavities, one for the 

 reception of the blood returned from the body, the other for its transmission. 



In this class, the nervous system is contained within the general envelope of the 

 body along with the viscera, and is composed of several scattered masses connected 

 by nervous filaments, the chief of these masses is placed on the asophagus or gullet, 

 and is called brain. Of the organs of sense, two only are found, those of taste and 

 vision, the latter of which is frequently wanting. In this class, one single family 

 presents the organ of hearing. The organs of digestion and secretion are nearly as 

 complex as in the vertebrata. Still, however, there is no skeleton, the muscles 

 are merely attached to the skin, which constitutes a soft contractile envelope, be- 

 tween the layers of which, in many species, are formed hard calcareous plates, 

 called shells. 



Finally, we arrived at the vertebrated animals, which are divided into two sec- 

 tions, from their possession of cold or warm blood. The former section is composed 

 of the fishes and reptiles exhibiting various degrees of complication. All, however, 

 have a muscular heart, and some kind of respiration, either by means of gills or 

 membranous lungs. The individuals of the latter division are distinguished by the 

 warmth of their blood, they have also a muscular heart, invariably divided into 

 four cavities, a mouth furnished with two jaws, the one situated either above or 

 before the other; here we always find five senses, never more than four limbs, a 

 brain exactly filling the cavity of the skull, a spinal marrow, and two kinds of 

 nerves. They also possess two kinds of muscles, of which the one set obey the 

 empire of the will, and are hence called voluntary, whilst the others are totally 

 independent of that power, and are termed the involuntary muscles, as the hea.rt, 

 &c. In this division are included the two classes of birds and mammalia, whicli 

 latter also includes the human species, distinguished by their erect posture, tfeat 



