SWAMMERDAM. 1 35 



microscope, they were so affected by it, that after 

 midday he could no longer trace the minute bodies 

 which he examined, although he had then as bright 

 a light as in the forenooa" 



Swammerdam investigated the nature of the 

 changes of outside form and internal structure 

 which accompany insect life. Some of his draw- 

 ings of the escape of the ephemera fly from its 

 sheath of delicate skin on the surface of the water, 

 and out of the wingless or nymph condition, are 

 very beautiful. But his accuracy regarding the 

 minute internal changes of the tissues and organs 

 in the larva, pupa, and perfect insect is being more 

 and more acknowledged. He taught that these 

 changes were not sudden, but that a continuous 

 growth of organs and tissues culminated at certain 

 times of the life of the insect. The larva, or cater- 

 pillar, admirably adapted for its course of life, was 

 a stage of the life cycle of a more perfect form, the 

 imago or flying insect. Swammerdam stated that 

 all the organs of the perfect insect— a butterfly, 

 for instance — were in a visible yet only slightly 

 developed condition in the caterpillar. And late 

 researches are leading to prove that he was right, 

 for the wings of the future fly are to be detected in 

 the body of the tiny crawling thing that escapes 

 from the egg, 



Happy in this toil when he was well, for it was 

 all about what was entirely new and previously 

 unknown, he often laboured on, when he was ill, 

 with "sighs and tears." Naturally sensitive, pious, 



