MALPIGHI, SWAMMERDAM, LEEUWENHOEK. 569 



the chick, as the most available form in which to gel an insight into 

 this process, but he could not extend his observations successfully into 

 periods earlier than about the twenty-four hour stage of develop- 

 ment. Two memoirs were written on this subject, both in 1672. Of all 

 Malpighi's work, this has received the leasi attention from reviewers, 

 but it is, for the time, a very remarkable piece of work. No one can 



Fig. :;. Mai.piuhi's Sketchks showing thk Embryological Development or the Chick. 



took over the ten folio plates without being impressed with the extent 

 and accuracy of his observations. His earliest sketches show an open 

 neural groove with an enlargement for the head end, and from this 

 stage onward he carries the development of the chick by sketches to 

 the period of hatching. These sketches are of interest not only to 

 .■students of embryology, but also to educated people, to see how far 



