•ii6 ESSAYS AND OBSERVATION^ 



publiftied on the motion of the blood,' 

 tells us, that he has frequently, in living 

 frogs, feparated the arteries from the two 

 lamellae of the mefentery, and from the 

 furrounding cellular membranes, and 

 found, that, as foon as he cut or wound- 

 ed the artery, an aneurifm was formed. 

 It is not only confirmed by experiments 

 and obfervations of this kind, that a- 

 heurifms may be formed in this manner, 

 but likewife by cafes which have occur- 

 red in pradice. Caefar Hawkens, Efq; 

 Serjeant Surgeon to his Majefly, told me; 

 that, in performing the operation for art 

 aneurifm which had appeared after a 

 •Wound in the fore arm, made with a 

 fmall fword, had been healed for fome 

 months, he found the artery dilated in- 

 to an oval cyfl, like to that of tab. i, 

 fig. i.N° 2. and not a cyft communicating 

 by a fmall hole with the cavity of the 

 artery, as is common. To be fure of not 

 being miftaken, he opened the cyfl: ; and, 

 after having taken out a polypous con- 

 cretion, he found the artery opening in- 

 to 



