of ninety-one; Malpighi, always in feeble health, but directing his efforts with rare capacity, reaching the age of sixty-seven; while the great intensity of Swammerdam stopped his scientific career at thirty-six and burned out his life at the age of forty-three.
They were all original and accurate observers, but there is variation in the kind and quality of their intellectual product. The two university-trained men showed capacity for coherent observations; they were both better able to direct their efforts towards some definite end; Leeuwenhoek, with the advantages of vigorous health and long working period, lacked the systematic training of the schools, and all his life worked in discursive fashion; he left no coherent piece of work of any extent like Malpighi's 'Anatome Plantarum' or Swammerdam's 'Anatomy and Metamorphosis of Insects.'
Swammerdam was the most critical observer of the three, if we may judge by his work in the same field as Malpighi's on the silkworm. His descriptions are models of accuracy and completeness, and his anatomical work shows a higher grade of finish and completeness than Malpighi's. Malpighi, it seems to me, did more in the sum total than either of the others to advance the sciences of anatomy and physiology and through them the interests of mankind. Leeuwenhoek had larger opportunity; he devoted himself to microscopic observation's, but he wandered over the whole field. While his observations lose all monographic character, nevertheless they were important in opening new fields and advancing the sciences of anatomy, physiology, botany and zoology.
The combined force of their labors marks an epoch in the establishment of the scientific method and in the ushering in of a new grade of intellectual life.
