250 PHILOSOPHICAL TRANSACTIONS. [aNNO 1668. 



a certain length, yet he says he could never find that the whole substance of 

 the testes could be untwined, like yarn from the spindle. 



In the concluding part of his letter. Dr. C. gives notice of his intention of 

 communicating to the world his observations on the organs of generation, and 

 on impregnation in the human subject, tracing its progress from the first fort- 

 night to the seventh and eighth months ; deduced from data, furnished partly 

 by abortions, and partly by dissections of women dying at different periods of 

 gestation. 



Explanation of the Figures referred to in this Letter. 



Figure 1 exhibits part of the vas deferens with the vesiculae seminales of one 

 side, as they appeared before they were cut out of the body. A, The angle of 

 communication. B, The upper extremity of the vesiculas seminales. C, The 

 vas deferens where a small injecting pipe was inserted. D, The foramen which 

 opens into the urethra, aaa. Part of the vas deferens, bbb. The vesiculae se- 

 minales. ccc. The duct which leads from the vesiculae into the urethra. 



Fig. 1 represents a part of the vas deferens, with the vesiculae seminales of 

 the other side, after being cut out, inflated, and dried for preservation. The 

 letters denote the same as in fig. 1 . 



Observations concerning the Comet tvhicli lately appeared in foreign 

 Parts, communicated from Italy and Portugal. N" 35, p. 683. 



The Italian account, given by Gio. Domin. Cassini: — 



Anno l668, the 10th of March, ih. of the following night, (after the Italian 

 way of counting) at Bononia, S. Cassini observed a path of light extended from 

 the Whale through Eridanus; which he judged to be the train of a comet, both 

 by the figure and colour, as also because that the direction of it, being by the 

 fancy continued, seemed to proceed to the 21st degree of Pisces, where the 

 sun then was, and so tended to the part opposite to the sun, like other comets. 

 By its extreme point reached to that star in Eridanus marked 14 by Bayer. 

 But it issued out of the horizontal clouds, so that it seemed the head of the 

 comet was either veiled by them, or hid under the horizon. It followed 



he afterwards distinguished himself as a teacher of anatomy. He died in l657, aged 80. He wrote 

 a Schola Anatomica ; Anatomica, Corp. Hum. j Osteologia ; Anthropologia (afterwards republished 

 with large additions under the title of Opera Anatomica) ; Enchiridion Anat. ; besides several con- 

 troversial tracts. He was a man of a most invidious and overbearing temper, and was almost constantly- 

 involved in disputes with contemporary writers, concerning some of the most important anatomical 

 discoveries which were then made. He would not allow Pecquet and Bartholine the merit of their 

 respective discoveries} and even attempted to refute Harvey's doctrine of tlie circulation of the 

 blood. 



