12 THE ANIMALS AND MAN 



"Place a bit of cover-glass over a very thin portion of the 

 fin and study it with higher power. Find two kinds of 

 corpuscles in the blood: (i) red corpuscles (red only when 

 a number are seen together), very numerous, and carried 

 along in the center of the larger currents closely packed 

 together; and (2) white corpuscles, . . . not very 

 numerous, and usually seen trailing along the edges of 

 the blood currents, or escaping out into the tissues." 



Sunfishes eat insects, shellfish, spawn of other fishes, but 

 not other fishes themselves. 



The females lay their eggs in shallow saucer-like depres- 

 sions on the stream bed, which are scooped out and cleared 

 of pebbles by the males. After laying her eggs the female 

 departs, leaving the nest to the exclusive care of the male. 

 The males are very active and pugnacious, defending the 

 nest with great bravery. This attention lasts, however, only 

 until the eggs hatch, which happens in a week or more, 

 depending on the temperature. The young fry are left to 

 care for themselves. 



The English sparrow (fig. 5). As the English sparrows, 

 which have spread over the whole country, are almost 

 universally held to be pests, the shooting of a few to serve 

 as specimens for the study of the external parts of a bird 

 may be looked on more leniently than the killing of other 

 birds should be. The habits of the live birds may be studied 

 as the pupils go and come from school or in the school 

 yard. 



Examine a dead specimen. Note the division of the 

 body into head, trunk, and appendages namely, wings 

 and legs. Note that the sparrow is covered with feathers, 

 some long, some short, in some places thick and in others 

 thin, but all fitting together to form a complete covering 

 for the body. Only the bill and feet are exposed, and 

 these are covered in one case (bill) with a horny sheath, 

 and in the other (feet) with horny scales. The feathers 



