VOL. II.] PHILOSOPHICAL TRANSACTIONS. 24() 



in the following year, 1667. Dr. C. then rectifies an error into which Mr. Ol- 

 denburg had fallen, respecting the time when the experiment of infusing liquors 

 into the veins was first tried by Dr. Christopher Wren ; showing that it was 

 performed in the house of the French ambassador, the Due de Bourdeaux, in the 

 year 1657, and not 1659, as would appear from Mr. Oldenburg's statement. And 

 the experiment (he says) was several times repeated in the course of that same 

 year. In regard to a certain Hamburgh physician who would attribute the in- 

 vention of infusing liquors into the veins to his countrymen (the Germans), 

 stating that he had heard of the experiment being made in the presence of a 

 prince of the Palatinate ; it is accounted for by the circumstance of the experi 

 ment having been performed before the Palatine Prince Rupert, in England, 

 through whose correspondence the fame of it might easily pass into Germany. 

 Moreover, Dr. Clarck remarks, that it appears from this physician's own words 

 that he had never tried this operation (though he says he had thought of it) at 

 the time he mentions. 



Dr. Clarck then observes, that with the present letter he sends a drawing of. 

 the vasa deferentia and vesiculae seminales, representing them in the state in 

 which they were cut out of the human body by Lower and himself. He con- 

 gratulates De Graaf, * or rather himself, that they both should have hit upon 

 the same discovery. So evident, he says, is the communication between the 

 vasa deferentia and vesiculas seminales, that if a person injects a liquor into 

 the vas deferens, not a single drop of it will get into the urethra before it has 

 reached the upper extremity of the vesiculae seminales. For in the angle A (see 

 figure 1, plate 8), this communication is so contrived, that the vesiculae seminales 

 must be entirely filled before any of the liquor can make its way into the ure- 

 thra. He allows that the semen is emitted into the urethra by two foramina; 

 but he cannot readily assent to De GraaPs doctrine, that there is but one ma- 

 terial of the seminal fluid (unam solummodo esse materiam seminis) ; for if the 

 testicle differs in its structure, colour, and substance, from the epididymis, in 

 the same manner as the epididymis differs from the prostate; and if in these 

 several parts we meet with juices that are of a different consistence and colour, 

 he infers that different materials of the seminal fluid are elaborated in them. 



With regard to De Graaf s and Van Home's assertion, that the substance of 

 the testicle is nothing but a conglomeration of funiculi, or rather extremely mi- 

 nute tubes ; this fact. Dr. Clarck remarks, was known to himself, as well as to 

 Riolan-J- and others, before. But although these funiculi may be drawn out to 



• Of whose anatomical labours an account has been already given at p. 241. (See also N° 38). 

 f John Riolan was the son of a physician of the same name^ and was bora in 1577 at Paris, where 

 VOL. I. I I 



