I3 6 SEVENTEENTH CENTURY. PT. in. 



colouring matter which gives him his dark colour is con- 

 tained in a deeper layer just at the point where the epidermis 



joins the dermis or real fib- 

 rous skin beneath (see Fig. 

 22.) This soft layer is still 

 called the ' Malpighian layer,' 

 and the different colours of 

 the skins of animals are 

 caused by little cells of col- 

 FlG - 22 - ouring matter which lie buried 



Section of the Skin (Huxley.) . 



a, F/pidermis. b, Its deeper layer, or 



Malpighian layer, c, Upper part of After Malpiglli had exam- 



the dermis, or true skin, da, Per- . t 



spiration ducts. ined many other minute struc- 



tures of the human body, he began next to study insects, 

 and in 1669 he published a beautiful description of the 

 silkworm. With his microscope he discovered the small 

 holes or pores which are to be seen along both sides of the 

 body of an insect, and he found that these pores were open- 

 ings into minute air-tubes, which pass into every part of 

 the insect's body, and form a breathing apparatus. He also 

 described the peculiar vessels in which the silkworm secretes 

 the juice from which its silk is made, and he traced the 

 changes which the different parts of the worm undergo as 

 it turns into the moth. In fact, he was the first man who 

 attempted to trace out the anatomy of such small creatures 

 as insects ; a study to which men now often devote their 

 whole lives. 



But grand as Malpighi's discoveries were, a Dutchman 

 named Leeuwenhceck (born 1632, died 1723) made the 

 microscope tell even a more wonderful tale, for he detected 

 in water and in the insides of animals those extremely 

 minute beings which he called animalcules. He showed 

 that a piece of the soft roe of the cod-fish not bigger than 



