286 NATURAL HISTORY OF AQUATIC INSECTS CH. 



the Silkworm a not inconsiderable advantage. His 

 working-life as a naturalist comes within the ten years 

 between 1663 and 1673 ; and this short space of time 

 was darkened by anxiety about money, as well as by 

 the religious fanaticism, which in the end completely 

 extinguished his activity. The vast amount of highly- 

 finished work which he accomplished in these ten 

 years justifies Boerhaave's rather rhetorical account 

 of his industry. Unfortunately, Boerhaave, whom we 

 have to thank not only for a useful sketch of Swam- 

 merdam's life, but also for the preservation of most 

 of his writings, was only twelve years old when the 

 great naturalist died, and his account cannot be taken 

 as personal testimony. Swammerdam, he tells us 

 worked with a simple microscope and several powers. 

 His great skill lay in his dexterous use of scissors. 

 Sometimes he employed tools so fine as to require 

 whetting under the microscope. He was famous for his 

 inflated and injected preparations. As to his patience 

 it is enough to say that he would spend whole days 

 in clearing a single caterpillar. Boerhaave gives us a 

 picture of Swammerdam at work which the reader 

 does not soon forget. " His labours were superhuman. 

 Through the day he observed incessantly, and at 

 night he described and drew what he had seen. By 

 six o'clock in the morning in summer he began to 

 find enough light to enable him to trace the minutiae 

 of natural objects. He was hard at work till noon, 

 in full sunlight, and bareheaded, so as not to obstruct 

 the light ; and his head streamed with profuse sweat. 

 His eyes, by reason of the blaze of light and micro- 

 scopic toil, became so \veakened that he could not 



