VOL. XXIII.] PHILOSOPHICAL TRANSACTIONS. 7| 



Plate 3, fig. 9, represents a yellow lily : a the top of the pistillum or tube, 

 at which the seminal plants are supposed to enter, and through which they are 

 conveyed to the unimpregnated seed in the seed vessel; bbb the apices seminir 

 formes, which, when open, shed that powder which enters the tube at a ; 

 c the place of the seed vessel at the bottom of the tube, the seed vessel itself 

 being concealed under the leaf in this figure. 



In fig. 10, D represents the siliqua in a flower of the pea-kind: e the tube 

 which arises from the siliqua, and conveys the plants to it ; f the membranous 

 coat that involves the siliqua, laid open; gggg the apices, which, before the 

 membranous tegument is laid open, appear to rise from its edges, and by the 

 petala of the flower are kept close upon the orifice of the tube, that they may 

 conveniently shed their farina into it. 



Fig. 1 1 is a French bean represented sidewise. Fig. 1 2 the same opened : 

 h the seminal plant , i a perforation, at which it is supposed the seminal plant 

 first entered. 



^n Experiment to discover the true Cause of the Motion of the Dura Mater, 

 By H. Ridley, M. D. Translated and abridged from the Latin, N° ?87, 

 p. 1480. 



Baglivy having advanced in his 4th book* de Fibra Motrice an opinion^f- 

 concerning the alternate movement of the dura mater, different from the ex- 

 planation given by Dr. Ridley in the 6th chapter of his Anatomy of the Brain; 

 the last mentioned physician was induced to subject this matter to the test of 

 experiment. 



Having tied down a dog and removed a part of the cranium, neither Dr. R. 

 nor his assistants could perceive any pulsation either of the dura mater or of 

 its longitudinal sinus; but a little while afterwards the aforesaid sinus being 

 wounded by the contact of a red hot iron introduced with a different intention, 

 a profuse haemorrhage ensued; by which means the vessels were considerably 

 unloaded ; after which the pulsation both of the sinus and of the whole dura mater 

 was very conspicuous. An incision was made into this sinus in its whole length, 

 in order to trace by the spirting out of the blood the insertion of arteries into 

 it, but in vain; although Vieussens and Wepfer mention that they detected 

 several such insertions. Hence it is evident (Dr. R. infers) that these sinuses 

 have no other motion but that which is communicated to them, as well as to 



* Lib. i. Cap. v. of the Venetian edition in 4to. 1752. 



t Baglivy supposed that the dura mater had, in consequence of its fibrous structure, a systaUie 

 action similar to that of the heart. 



