1 9 2 Scientific Intelligence — Zoology. 



way to turn, when his compass has become sluggish, his timepiece 

 out of order, the plants which he may happen to meet will shew him 

 the way ; their sleeping leaves tell him that midnight is at hand, and 

 that at that time the sun is standing in the north. — (American An- 

 nual of Scientific Discovery, p. 231.) 



ZOOLOGY. 



13. Professor Agassiz on the Colour of Animals. — Professor 

 Agassiz is of opinion that the coloration of the lower animals living 

 in water, depend upon the condition, and particularly upon the depth 

 and transparency of the water in which they live : that the colora- 

 tion of the higher types of animals is intimately related to their struc- 

 ture ; and that the change of colour which is produced by age in many 

 animals is connected with structural changes. Coloration is valuable 

 as an indication of structure ; and it is a law universally true of 

 vertebrated animals, that they have the colour of the back darker 

 than that of the sides ; and that the same system of coloration pre- 

 vails in all the species of a genus, partially developed in some, but 

 recognisable when a large number of species is examined. 



14. The Tsetse, or Zimb, of South Africa, — The Tsetse is the 

 name given to an insect found in the interior of South Africa. The 

 most curious fact about this insect is, that while its sting is harm- 

 less to man and wild animals, it is certain destruction to horses, 

 cattle, sheep, dogs, or any other domesticated brute, except goats and 

 young calves. Several instances are known where all the cattle, 

 horses, and dogs, of a traveller have been swept off by it. A horse 

 was taken among them by a doubter; about fifty settled on him, 

 and immediately he began to lose flesh ; in eleven days he was 

 dead. When an ox is bitten, at once the countenance stares, the 

 eyes run, he loses strength, swells under the jaw, staggers, grows 

 blind, and becomes emaciated, which continues sometimes for 

 months, when death ensues. Upon removing the skin, a great 

 many air-bubbles are found on the surface of the body, under the 

 cellular membrane. The fat is of an oily, glassy consistence, and 

 of a greenish-yellow colour. The heart is soft and pale, lungs and 

 liver diseased, and the gall-bladder unusually distended with bile. 

 The muscles are flabby, the blood contains very little colouring 

 matter, and not a pailful is found in the body. There is no such 

 thing as becoming accustomed to them, and the natives in the loca- 

 lities where they abound, are unable to raise a single domestic ani- 

 mal. In the same districts, elephants, buffaloes, zebras, gnus, &c, 

 live unaffected by the tsetse. A dog fed on the meat of game, 

 lives ; one reared on milk, falls a victim to them. It is said that 

 game meat is possessed of a peculiar acid found but sparingly in 

 tame animals ; perhaps this may be the antiseptic. But then why 

 do calves who subsist on milk escape ? Sometimes an entire herd of 

 cattle is cut off, excepting the calves, and these follow likewise if 

 kept in the region for a year or two. — (American Geographical 

 Society.) 



