ZOOLOGY. 35 1 



brane. Cells thus produced artificially, however, though precisely similar 

 to those formed by the natural fabric, will not undergo further progress. 

 Life cannot be imparted artificially ; vitality is not within the reach of ex- 

 periment. 



In all organized bodies, however, there is a wearing away of the constitu- 

 ent particles of which their various organs are composed. Each physical 

 or mental exertion involves the destruction of materials, requiring the aid 

 of nourishment to sustain and maintain the balance between the growth 

 and loss of these bodies. Sustenance is necessary, and of the most varied 

 kind. The wants and propensities of the various species of beings are dif- 

 ferent ; different food must be selected by different races, and other means 

 adopted to preserve their perpetuity of existence. 



Allusion was also made to the subject of digestion, the formation of chyme, 

 chyle, the lymph, fibrine, blood, and other fluids by which the process of 

 life is maintained, and facts were adduced, showing that the entire econo- 

 my of organic bodies is but an elaboration of cells, the immaterial or spir- 

 itual principle, which resides in them all, disposing of and arranging the 

 cells according to the plan stamped upon each species. The constituents 

 of the blood, its circulation, and the very important part it bears in pre- 

 serving and maintaining ^the other functions of the body in a state of 

 health and activity, were made a particular point of consideration. 



In speaking of nutrition, the author said, " This is the last word in 

 physiology ; the last word of physiology is the first word in clinical medi- 

 icine a science which, without the aid of physiology, would be but an art. 

 Surgery or operative medicine rests entirely upon anatomy. The better 

 the human organism is known to the operator, the better will his operations 

 be performed, so that the last word of anatomy will be the first word of 

 surgery. At the bottom of physiology and medicine clinical and opera- 

 tive will be found embryology." 



NATURAL HISTORY OF CENTRAL AFRICA. 



The following extracts from a letter received from Dr. Vogel, the astrono- 

 mer and naturalist, now at Lake Tsad, give a characteristic description of 

 those countries and its productions : 



"This is really a terrible country. Whoever expects to meet with 

 tropical abundance here will be sadly disappointed. With the greatest 

 assiduity, for a period of nearly five weeks, I have been unable to discover 

 and collect more than seventy-five different plants. The forests, for the 

 most part, consist merely of acacias (only two sorts) and tamarind trees ; 

 palms (doona) are only to be -found about fifty miles north, on the River 

 Yeou. Not a single tree or shrub is devoid of prickles. Perhaps the land 

 presents a more refreshing prospect after the rainy season, for almost all 

 the grasses and the more delicate plants are already quite burned up by 

 the sun, the thermometer frequently rising above 100 F., even from the 

 beginning of February. 



