Packaro] insects of THE POND AND STREAM. 131 



is able to reflect on this progress of life as the beneficent 

 result of the struggle, mental and physical, for existence, of 

 his own and other species ; such an one, unless his faculties 

 are quite unequally developed, cannot avoid a rational com- 

 bination of materialism and spiritualism in his intellectual 

 make-up. The very faculty he possesses of making this 

 retrospect and studying his own mental operations, and of 

 appreciating the Infinite Power working in material laws, 

 separates him from the animals, and should teach him that 

 he is not subject alone to physical, material laws. 



So if, in looking back, the picture of the animal world 

 evolving from a mere drop of protoplasm, of humanity 



struggling up from some ape-like 



'^^ => ^ ' Fig. 91. 



form, seems sad, tragic, and gives a 

 shock to the sensibilities of many, 

 the final result is liopeful and inspir- 

 ing. In connection with tliese pro- 

 found problems of our own existence, 

 the study of the hal)its, economy, 

 structure and embryology of animals, 

 their various contrivances for the 

 maintenance of life, their evident en- 

 joj'ment of life as long as it lasts, the ''"'^* 



gleams of intellect flashing out in their daily acts, all derive 

 a fresh and startling interest. 



Among aquatic insects there are marvels of mechanical 

 skill displayed in the construction of the bodies of tiie swim- 

 ming and diving forms. The Gerris, or Wherrj^man (Fig. 

 91), of our streams, ages ago anticipated our racing boats 

 and wherries. Our diving macliines, whether known to their 

 inventors or not, are modelled on the principle of the diving 

 beetle and the diving spider. Tlie mechanism of swimming 

 in the Dytiscus engaged the attention of Straus-Durchheim, 

 the famous, French anatomist. Models of scissors, straight 

 and curved, that would give new ideas to a Sheffield mnnu- 



3 



