62 ON THE PLACE OF MAN IN THE SCALE OF BEING. 



suspended in the midst of the white albumen, that, when the egg is laid upon 

 its side, it will always rise to the highest part of it; and the relative weight 

 of the several parts is further adjusted in such a manner, that the cicatricula 

 or germ-spot shall always be at the point nearest the shell, so as to come into 

 the closest proximity with the source of heat, and also to be in the most im- 

 mediate relation with the surrounding air. There are some Birds, inhabiting 

 the equatorial region, which do not always incubate their eggs, trusting to the 

 solar heat for their maturation. It is said that the Ostriches of the intertro- 

 pical deserts are content with covering their eggs with a thin layer of sand, 

 so as to admit the action of the sun by day, and to keep them warm at night ; 

 but that those living under a less constantly elevated temperature, sit upon 

 their eggs if not constantly, at any rate when the solar heat is not sufficient. 

 This statement has been disputed ; but its truth seems to be confirmed by a 

 curious observation made by Mr. Knight, that a Fly-catcher, which built for 

 several years in one of his hot-houses, sat upon its eggs when the temperature 

 was below 72, but left them when it rose above that standard. Certain Birds 

 inhabiting New Holland, deposit their eggs in a sort of hot-bed, composed of 

 decaying vegetable matter; a number associating together for the construction 

 of this artificial incubating apparatus, although they live separately at other 

 times. The degree of assistance afforded by the parent Birds to their young, 

 after their emersion from the shell, varies much in different tribes ; in general 

 it may be remarked, however, that it is most prolonged in those which ulti- 

 mately attain the highest development, and especially in those whose intelli- 

 gence becomes the greatest. Thus the Chicken and the Duckling, when just 

 hatched, are able to shift for themselves ; but among the Raptorial and Inses- 

 sorial Birds, which rank far higher in the scale, the young is for a long time de- 

 pendent upon the parent for food ; and in the Parrot tribe, which unquestion- 

 ably surpasses all others in intelligence, the parent not only supplies its young 

 with food which it has obtained for them, but partly nourishes them by a 

 milky secretion from the interior of the craw ; impregnating with this the 

 aliment which it swallows, and which it afterwards disgorges for its offspring. 



10. General characters of Mammalia. 



42. The MAMMALIA are universally regarded as the highest group in the 

 Animal kingdom ; not only from being that to which Man belongs (so far, at 

 least, as his bodily structure is concerned), but also as possessing the most 

 complex organization, adapted to perform the greatest number and variety of 

 actions, and to execute these with the greatest intelligence. The contrast is 

 here extremely strong between the reasoning and the instinctive powers ; 

 even when we put Man out of view. When we compare, for example, the 

 sagacity of a Dog, Monkey, or Elephant, and the great variety of circum- 

 stances in which they will display an intelligent adaptation of means to ends, 

 with the limited operations of Insects, over which the judgment and will seem 

 to have no control, we cannot help being struck with the difference. The 

 former are educable in the highest degree next to Man; the latter could not 

 be made to change their habits, in any essential degree, by the most prolonged 

 course of discipline. Man is actuated, like the lower animals, by instinctive 

 propensities, which have an immediate bearing on his corporeal wants ; whilst 

 they have, like him, the power of adapting their actions to gain certain ends, 

 of which they are conscious. A Dog or an Elephant may show more real 

 wisdom, in controlling for a time its instinctive propensities, from the desire 

 to accomplish some particular object, than is displayed by many Men, who 

 give free scope to the exercise of their sensual passions, although warned by 

 their reason of the injurious consequences of such indulgence. 



