84 THE COCKROACH : 



and Ht. (Insect) = Ht. (Viper). The Viper's efficiency as a 

 leaping animal would, therefore, equal that of a Cheese-hopper 

 if it leaped the same vertical height. Therefore, if. the two 

 animals were "endowed with similar powers," the heights to 

 which they could leap would be equal, and not proportional to 

 their lengths, as is assumed in the passage quoted. 



Straus-Diirckheim observes that a Flea can leap a foot high, 

 which is 200 times its own length, and this has been considered 

 a stupendous feat. It is really less remarkable than a school- 

 boy's leap of two feet, for it indicates precisely as great 

 efficiency of muscles and other leaping apparatus as would be 

 implied in a man's leap to the same height, viz., one foot.* 



The Fat-both/. 



Adhering to the inner face of the abdominal wall is a cellular 

 mass, which forms an irregular sheet of dense white appearance. 

 This is the fat-body. Its component cells are polygonal, and 

 crowded together. When young they exhibit nuclei and 

 vacuolated protoplasm, but as they get older the nuclei dis- 

 appear, the cell-boundaries become indistinct, and a fluid, loaded 

 with minute refractive granules, f takes the place of the living- 

 protoplasm. Rhombohedral or hexagonal crystals, containing 

 uric acid, form in the cells and become plentiful in old tissue. 

 The salt (probably urate of soda) is formed by the waste of 

 the proteids of the body. What becomes of it in the end we 

 do not know for certain, but conjecture that it escapes by the 

 blood which bathes the perivisceral cavity, that it is taken up 

 again by the Malpighian tubules, and is finally discharged into 

 the intestine. The old gorged cells probably burst from time to 

 time, and the infrequency of small cells among them renders it 

 probable that rejuvenescence takes place, the burst cells passing 

 through a resting-stage, accompanied by renewal of their 

 nuclei, and then repeating the cycle of change. 



The segmental tubes forming the Wolffian body of Verte- 

 brates have at first no outlet, and embryologists have hesitated 



* In any comparison it is necessary to cite not the height cleared by the man, but 

 the displacement during the leap of his centre of gravity. 



t The granules are not shown in the figure, having been removed in the prepara- 

 tion of the tissue for microscopic examination. 



