152. THE HISTORY OF BIOLOGY 



this work he ranks by the side of Harvey as one of the leading pioneers of 

 modern biology. 



"As is generally done in other physical-mathematical sciences, we shall 

 endeavour, with phenomena as our foundation, to expound this science of 

 the movements of animals; and seeing that muscles are the principal organs 

 of animal motion, we must first examine their structure, parts, and visible 

 action." In these words Borelli states his views on the function of biology 

 and thereby declares his starting-point to be Galileo's conception of nature, 

 and the work reveals the fact that here, as with Galileo, we are face to face 

 with "a new science." Even the very arrangement is original: by means of 

 short sentences, which, on the model of Euclid, are called propositions, with 

 accompanying proofs and corollaries, the inquiry is led from the simplest 

 element of the motory system, the individual muscle, gradually to more and 

 more complicated organs and organic systems, until finally the whole of the 

 being's power of movement is described in the form of a summary. First of 

 all, of course, he discusses the movements in man, to whom the lion's share 

 of the work is devoted, after which he studies the movements of mammals, 

 the flight of birds, the swimming of fishes, and even the characteristic move- 

 ments of insects and others of the lower animals. The first propositions are 

 introduced by an analysis of the actual muscular substance, Borelli maintain- 

 ing that these elements of bodily movement are identical with the flesh — 

 which the Aristoteleans denied. Then he describes in detail the different 

 mechanical functions of the muscles, this being clearly explained in schematic 

 form, with figures appended. On this basis he then proceeds to a study of the 

 different forms of movement: first the individual extremities, then the move- 

 ment of the whole body under different kinds of action, lifting, walking, 

 running, jumping; and even, what was for a southerner an unusual form of 

 motion, that of skating is observed and analysed. After the movements of 

 mammals, as above mentioned, have been examined, he describes birds' 

 power of flight in comparison with the foregoing movements, and finally he 

 analyses the action of swimming, in which he pays attention not only to the 

 motory system of fishes, but also to the possibilities of man and other land- 

 creatures in this respect. In connexion herewith Borelli puts forward sug- 

 gestions for a diver's dress and a submarine vessel; whether he was ever in a 

 position to make practical tests of these inventions history does not relate. 



M-Uscular -physiology 

 In another part of his work Borelli seeks to explain the causes of muscular 

 action. For this purpose he first of all tries a number of purely mechani- 

 cal alternatives, which he rejects, among them being the possibility of the 

 muscle's being shortened merely by contracting its mass, produced by the 

 concentration of its smallest particles. Such takes place, according to Borelli, 

 when a piece of red-hot wire becomes shorter on cooling, but this cannot be 



