LIFE AND WORKS OF NICOLAUS STENO 



XXIII 



been able to discover what both Aristotle and Steno had found, was 

 that there is another species of shark, common in the Mediterranean 

 (Mustelus vulgaris) and closely related to the Galeus Ixvis, with which it 

 is easily confounded, and this shark, though viviparous, has no placenta. 



Finally there is a little Treatise by Steno founded on the investiga* 



tion of a hare, in the one cornu uteri of which was found a fetus 



sartly resorbed, but to the astonishment of Steno not putrefied. Hence 



le concluded that women may hope that dead fetus, which are not 



Dorn in the natural way, may be resorbed without any putrefaction 



taking place. The fetus underlying this observation was probably a 



mummified one. 



Steno published a number of minor scattered observations and re* 

 marks on anatomical and physiological subjects, among others on the 

 image of the sun in the eye ; on the effect of snuff on the eye ; on the ve« 

 sicles.which Malpighi found in the lungs ; on the liver of over*nourished 

 animals; on the muscular fibres of the membranes surrounding the 

 lungs (of a swan), which he thought were of use in the respiration, 

 cxc. &c. It would carry us too far to enter upon these and other questions, 

 as well as on Steno s descriptions of the particular dissections of various 

 animals. An exception will only be made, as far as his publications on 

 certain fishes (sharks and rays) are concerned, partly because they 

 are most interesting in themselves, and partly because they form the 

 connecting link between Steno's works on anatomy and physiology 

 on one side and his works on geology on the other. 



The first fishes, of which Steno gave a description, were two rays. 

 Having mentioned the system of the mucous canals, also a discovery 

 of his, he went on to describe the position of the viscera, the glands 

 of the stomach and the intestines, and the spiral lamina of the latter, 

 which he also was the first to describe, fully realizing its importance to 

 the digestion, in that it makes up for the greater length of the intestines 

 in other animals. As has already been mentioned, he also touched 

 upon the question of the egg-shells of the rays. Furthermore he de* 

 scribed the structure of the branchiae, pointing out that the latter were 

 constructed in such a manner that the water could only pass one way, 

 the result being a constant supply of fresh water to the fish. He was 

 of the opinion that the fishes were breathing in this manner, but said 

 that the term respiratio might not be the correct one, when the matter 

 in question was water; according to his belief the water in itself 

 played the same part in the respiration of the fishes, as did the 

 air in the respiration of the animals provided with lungs. It must be 

 borne in mind that Steno wrote before Boyle and a hundred years 

 before the discovery of the oxygen. After having meditated on the 

 connection between the process of respiration in fishes and their lack 

 of voice he proceeded to describe the operculum pupillare, by which 



Various Mi= 

 nor Anato- 

 mical and 

 Physiologic 

 cal Observa- 

 tions. 



Rays and 

 Sharks. 



