ON BIOLOGY. 11 



ately after its birth, as well as its various metamorphoses 

 afterward. 



In his first class he placed the spiders and other species 

 which upon hatching have a form more or less like the 

 parent form. In this group he also included the slugs, 

 and leeches, which, of course, are not insects at all. A 

 second class included the grasshoppers and their kind, or, 

 as he points out, those insects which have six feet upon 

 being born and at a later period shed that covering be- 

 neath which the future wings are hidden. He was 

 also struck by the jumping power of this class. Thirdly, 

 he had a class for the caterpillars, which, as we know, 

 are hatched as worms and later assume the various 

 chrysalis forms, and still later emerge as moths and but- 

 terflies and their allies. Lastly, or in his fourth class, 

 he placed such insects as the common fly, which emerge 

 as worms upon hatching from the egg, and later assume 

 a pupa stage enveloped in an investing shell of their own, 

 which protects them until they take on the winged state. 



Swammerdam in many respects was a remarkable man; 

 his personal history forms one of the most interesting 

 pages on the growth and development of zoological 

 science. Toward the close of his life, he carried his 

 studies to such an excess as to utterly ruin his otherwise 

 powerful constitution; he then became a fanatic in relig- 

 ion, careless of his work and its results, and, finally, died 

 a victim apparently of melancholia brought on by his 

 unhealthy religious broodings. We must believe that 

 somewhat earlier in his life, or about 1674, these were 

 much aggravated by the control over his mind which had 

 been gained by that notable mystic, Antoinette Bourignon, 

 a woman whose religious ideas and professions were by 

 no means carried out in her daily course of conduct. 



In England, Sir Hans Sloane and Jno. Ray, during the 

 latter part of the Seventeenth and early part of the 

 Eighteenth Centuries, accomplished a great 

 deal to place the natural sciences upon the 

 most substantial footing. Ray especially was a 

 very learned man, and a voluminous writer upon sub- 

 jects connected with his chosen profession. With two or 

 three favored pupils he traveled much over Europe, and 

 made some very admirable and extensive collections in 

 animals and plants, which were brought back to England 

 to be worked up at his leisure. Ray also did much 

 toward classifying the forms he studied, and as a rule 

 his terse and classical descriptions were excellent, which 

 same favorable criticism, however, cannot be extended to 



