5gO PHILOSOPHICAL TRANSACTIONS. £aNNO I67I. 



in the tortoise, in lizards, and the like, the oblong trachea, divided into two 

 branches, supplies the pulmonary vesicles with air. I know that in frogs there 

 are two vesicles near the mouth, but separate and distinct from the lungs ; these 

 oral [or supra-guttural] appendages are every now and then distended by the 

 air driven from the lungs into the cavity of the mouth, during the act of expi- 

 ration. 



The lungs, as above described, are invested with a reticular muscle, of which 

 I have elsewhere rudely delineated the fleshy plexuses, sinuses, and vesicles. 

 The admirable structure of this muscle is particularly conspicuous in frogs and 

 lizards ; its numerous longitudinal fleshy fibres are mutually intersected by trans- 

 verse muscular fibres, and the interstices are occupied by reticular fleshy plexuses 

 much in the same manner as is seen in the leaves of trees. The aforesaid small 

 intermediate spaces are furnished with a set of straight fibres, or, as it were, 

 short tendons. This remarkable muscle is not only spread over the whole sur- 

 face of the lungs, but also invests all the interior vesicles and sinuses ; so that 

 every part of the lungs being compressed by its action, expiration and sound are 

 produced. A similar structure is observed to a certain degree in the lungs of 

 more perfect animals, ^nd is particularly apparent in the extreme lobules of 

 lambs, when those lobules are distended with air, and so long as they continue 

 moist and soft. 



The fibres of the spleen, concerning which such various opinions and con- 

 jectures have been offered, are not nervous (as, indeed, I myself once imagined) 

 but fleshy [muscular] in such manner, that from the outer fleshy covering, and 

 the fibres that run in a transverse direction, a peculiar muscle is formed, which 

 compresses the cells of the spleen, whereby the blood is propelled into the 

 splenic branch ; after a structure and manner not unlike that which we see in 

 the auricles of the heart. 



Nature has bestowed upon the testicles of a horse a structure somewhat si- 

 milar; for their inner coat contains a set of fleshy fibres, or a muscle pervading 

 the medituUium, together with the varicose vessels (una cum varicosis vasis). 

 These fibres having diff'erent directions like those of the spleen, and running 

 crosswise, so as to form a net-work, support and compress the congeries of 

 [seminal tubes, or] canals.* 



Bologna, February, 1671. 



* There is something of imagination intermingled with these observations of Malpighi, especially 

 in what relates to the spleen and testes. In the latter he seems to have taken portions of cellular 

 membrane for muscidar fibres. 



