226 



also, in some measure, between the lateral portions of the prostate 

 gland and the bladder. It was evidently a lobe of the prostate gland ; 

 and its ducts passed directly through the coats of the bladder, and 

 opened immediately behind the verumontanum. 



A still more distinct appearance of this lobe was afterwards found 

 in a subject twenty-four years of age ; a representation of which 

 accompanies this paper. 



This newly acquired anatomical fact enables us, Mr. Home says, 

 to understand the nature of a disease, of which we could not have a 

 clear idea while we were ignorant of the existence of the part in 

 which it originates : it also enables us to explain various circum- 

 stances respecting the disease, particularly what to our author has 

 ever appeared the greatest difficulty, namely, the protrusion of the 

 tumour into the cavity of the bladder. This protrusion arises from 

 the hard substance of the coats of the vasa deferentia being in close 

 contact, and bound down upon the lobe ; so that, from its first en- 

 largement, it must press up the thin coats of the bladder. The situa- 

 tion of this lobe, and its connexion with the vasa deferentia, also 

 render it liable to many causes of swelling, from which the body of 

 the gland is free ; since every irritation of the seminal vessels, or of 

 their orifices, may be communicated to it by continuity of parts. 



There is much reason, our author says, to believe that the diseased 

 state of the lateral parts of the gland, so common in the later periods 

 of life, has its origin in the lobe here described ; for, in most of the 

 cases examined by him, this lobe has been enlarged in a much greater 

 degree, in proportion to its size, than any other part of the gland ; 

 and the difficulty in passing the urine, which comes on very early in 

 the disease, is, Mr. Home thinks, owing to the enlargement of this 

 lo"be ; since an enlargement of the lateral portions of the gland widens 

 the canal instead of diminishing it. The enlargement of the lobe also 

 occasions the bladder to retain a considerable part of the urine ; and 

 as the urine passes in a stream, and the quantity voided is sufficient, 

 no suspicion is entertained of the cause of the frequency and distress 

 in passing it ; but they are referred to an irritable state of the coats 

 of the bladder. 



From the above observations it appears that the small lobe of the 

 prostate gland here treated of is, from its situation and the circum- 

 stances in which it is placed, more liable to become diseased than 

 any other part of the gland ; and that it produces symptoms of dan- 

 ger and distress which are peculiar to itself, but which have been 

 hitherto supposed to arise from the body of the gland becoming en- 

 larged. 



On the Quantity and Velocity of the Solar Motion. By William Her- 

 schel.JLLJ). F.R.S. Read February 27, 1806. [Phil Trans. 1806, 

 p. 205.] 



The present paper is a continuation of that communicated to the 

 Society by Dr. Herschel last year, in which he considered the direc- 



