SECT. 3] AND EIGHTEENTH CENTURIES 133 



not to be supposed a forming virtue or Vis Formatrix of an unknown 

 power and operation, as those that consider things suddenly and in 

 grosse do use to put. Yet in discourse, for conveniency and shortnesse 

 of expression we shall not quite banish that terme from all commerce 

 with us; so that what we mean by it be rightly understood, which is 

 the complex assemblement, or chain of all the causes, that concur 

 to produce this effect, as they are set on foot to this end by the great 

 Architect and Moderatour of them, God Almighty, whose instrument 

 Nature is : that is, the same thing, or rather the same things so ordered 

 as we have declared, but expressed and comprized under another 

 name." Thus Sir Kenelm admits that it is allowable to speak of the 

 "complex assemblement" of causes, as if it were one formative virtue, 

 and this corresponds to Roux's "secondary components" or interim 

 embryological laws. But that the portmanteau generalisations can 

 be resolved into ultimate physico-chemical processes, Digby both 

 believes and spends two entire chapters in trying to show. Digby 

 has been one of the two seventeenth-century Englishmen most under- 

 estimated in the history of biology, but his place is in reality a very 

 high one. How far he was in advance of his time may be gauged 

 from the work of his contemporary Sperlingen, whose book of 1641 

 was thoroughly scholastic and retrograde. 



His Treatise on Bodies evoked several answers. Undoubtedly the 

 most interesting from the progressive side was that of Nathaniel 

 Highmore, who will always be well remembered in embryological 

 history. Highmore's The History of Generation came out in 1651, so 

 that Harvey must have known of it, and it is one of the puzzles of 

 this period why Harvey did not make any mention of it in his work, 

 especially as J. D. Horst in a letter to Harvey refers to Highmore as his 

 pupil. Harvey replying in 1655 said he had not seen Highmore for 

 seven years. Highmore's title-page expressly states that his book is 

 an answer to the opinions of Sir Kenelm Digby. But before dis- 

 cussing in what the answer consisted, we may look at the plate which 

 is bound in immediately after the dedication (to Robert Boyle). 

 It is interesting in that it shows again the idea initiated by Leonardo, 

 namely, that all growing things, plants as well as animals, have an 

 umbilical cord, and in that the drawings of the chick embryos and 

 eggs are more quaint than accurate (Plate VI). 



Highmore first describes the Aristotelian doctrine of form and 

 matter, and then censures both it and the extensions of it with their 



