INTRODUCTION OF THE MICROSCOPE 67 



vat ions successfully into periods earlier than about the 

 twenty-four-hour stage of development. Two memoirs were 

 written on this subject, both in 1672, which were published 

 by the Royal Society of England under the titles De Forma- 

 tions Pulli in Ovo and De Ovo Incubato. Of all Malpighi's 

 work, this has received the least attention from reviewers, 

 but it is, for his time, a very remarkable achievement. No 

 one can look over the ten folio plates without being impressed 

 with the extent and accuracy of his observations. His 

 sketches are of interest, not only to students of embryology, 

 but also to educated people, to see how far observations 

 regarding the development of animals had progressed in 1672. 

 Further consideration of his position in embryology will be 

 found in the chapter on the rise of that subject. 



Little is known regarding the form of microscope em- 

 ployed by Malpighi. Doubtless, much of his work was done 

 with a simple lens, since he speaks of examining the dried 

 lungs with a microscope of a single lens against the hori- 

 zontal sun; but he is also known to have observed with an 

 instrument consisting of two lenses. 



Malpighi was a naturalist, but of a new type; he began to 

 look below the surface, and essayed a deeper level of analysis 

 in observing and describing the internal and minute structure 

 of animals and plants, and when he took the further step of 

 investigating their development he was anticipating the work 

 of the nineteenth century. 



Jan Swammerdam (1637-1680) 



Swammerdam was a different type of man — nervous, 

 incisive, very intense, stubborn, and self-willed. Much of his 

 character shows in the portrait by Rembrandt represented 

 in Fig. 15. Although its authenticity has been questioned, 

 it is the only known portrait of Swammerdam. 



