LIFE AND WORKS OF NICOLAUS STENO XVII 



essentiatn, id qvod &■ de auviculis patebit verum, &c. Bartholin was far 

 from admitting the correctness or Steno's view. Hippocrates himself, it 

 is true, had already called the heart a muscle; but at Steno's time this 

 view was completely overshadowed by that of Galen, and Steno was 

 quite aware that his assertion would be received with the strongest 

 opposition. He was likewise aware that it was not sufficient to make 

 an assertion, but that a proof of its correctness might justly be claimed, 

 and so he went the way of investigating the anatomy and physiology 

 of the ordinary muscles, afterwards comparing the results of his 

 researches with those attained by an examination of the anatomy and 

 physiology of the heart. As early as in the year after he had written his 

 Letter to Bartholin, Steno published his first Treatise on the muscles. 

 He begins his Treatise by mentioning the anatomy and physiology 

 of some particular muscles, first of all the respiratory ones; he corrects 

 some errors in the current view of the latter, explains various pheno* 

 mena, and gives their name to the levatores costarum muscles. Then 

 he shows that the tongue does not, as was generally supposed, con? 

 sist of a substance of its own, neither is it a gland, as Wharton among 

 others maintained, but it is altogether made of muscular fibres, the 

 course of which he describes. He also describes the two spirals of the 

 muscular fibres, which cross in the oesophagus of the mammals. Pro* 

 ceeding to speak of the general anatomy and physiology of the muscles, 

 Steno furthermore says that the muscles do not, as was then generally 

 supposed, consist of a parenchyma, caro, and muscular fibres, but are 

 entirely made of fibres, to which must only be added arteries, veins, 

 nerves and thin layers of fibrous tissue. The fibres, fibraz motrices, he 

 again divides into fibrils, jibrillx minutissimx, and every muscular fibre, 

 according to his opinion, is continued at either end of the muscle in a 

 tendinous fibre, so that every one of the tendons belonging to a muscle 

 has a number of tendinous fibres corresponding with the number of 

 muscular fibres in the muscle. But when examining the heart Steno 

 here also found nothing but muscular fibres (terminating in tendinous 

 fibres), vessels, nerves and some connective tissue; and having found 

 that also in the heart the function of these fibres was contraction, 

 he concluded that the heart itself was a muscle and nothing but 

 a muscle. Moreover Steno very carefully examined the course of the 

 fibres in the heart, found the bending of the fibres at the apex and 

 the different degree of obliquity of the different layers of fibres, which 

 results were shortly afterwards carried further by Borelli. Finally Steno 

 maintained that the fact of the contraction of the heart not being vo* 

 luntary cannot be used as an argument against the heart's being a 

 muscle, because many muscles, universally recognized as such, contract 

 involuntarily. In thus showing what the heart is, Steno at the same 

 time showed what it is not. He says himself: Non erit cor amplius sui 



