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POPULAR SCIENCE MONTHLY. 



command. They show successive stages from the time the embryo 

 is first outlined, and, taken in their entirety, they cover a wide range 

 of stages. 



His observations on the development of the heart, comprising 

 twenty figures, are the most complete. He clearly illustrates the 

 aortic arches, — those transitory structures of such great interest as 

 showing a phase in ancestral history. 



He was also the first to show by pictures the formation of the 

 head-fold and neural groove as well as the brain vesicles and eye 



Fig. 3. Maecellus Malpighi (1G28-1694.) 



pockets. His delineation of heart, brain and eye vesicles are far 

 ahead of those illustrating Wolff's ' Theoria Generationis ' made nearly 

 a hundred years later. But Wolff rose to a higher level in his later 

 work on the development of the intestine, and produced some figures 

 better than any of Malpighi's. 



The original drawings for ' De Ovo Incubato,' still in possession 

 of the Royal Society, are made in pencil and red chalk. They far 

 surpass the reproductions in finish and accuracy. In looking them 

 over in 1902, I noticed four aortic arches represented in one figure 

 where the engraver has shown only three. 



The portrait of Malpighi shown in Fig. 3 is taken from his Life 



