OTHER GLANDS. 331 



the frenum lingua. No chemical experiments have hitherto 

 been made upon this glan 1. 



The sublingual gland is much smaller than either of the pre- 

 ceding. It lies beneath the tongue close to the side of its fr> 

 num. Its secretion is poured into the mouth by several minute 

 orifices, which open beneath the tongue on each side. Nothing 

 is known concerning its chemical constitution. 



2. The testes are two in number, and some time before birth 

 lie on the psoas muscle near the lower extremity of the kidneys. 

 Each of them is invested by a proper capsule, and receives, besides, 

 a partial covering from the peritoneum. About the eighth month 

 the testis enters the ring lying behind the process of the perito- 

 naeum, which goes out of the abdomen by the inguinal canal, and 

 in the ninth month it is found in the bottom of the scrotum. 



The testis is enclosed in a firm capsule called the tunica al- 

 luginea. It is of a clear white colour, dense, and fibrous, and the 

 fibres interlace in every direction. At the posterior border it 

 separates into two laminae ; one of which, the external, is conti- 

 nued to the vas deferens. The inner surface of the albuginea is 

 lined by a delicate membrane formed of the ultimate ramifica- 

 tions of the spermatic blood-vessels, united by a little cellular 

 tissue, and thence called tunica vasculosa. The testis itself, be- 

 low these coverings, has the appearance of a soft, pulpy, dark yel- 

 low mass, divided into lobes. It is composed of a great number 

 of minute tubes, called tubuli seminiferi, which do not communi- 

 cate with each other. The lobes differ in size, some containing 

 one, and others a greater number of seminal tubes. Their shape 

 is somewhat conical ; the large end of which is directed towards 

 the circumference of the testis. 



The seminal tubes are the vessels in which the semen is se- 

 creted. According to Monro they are about 300 in number, 

 the length of each is about sixteen feet, and the diameter about 

 3^-oth of an inch. Each of these small vessels commences by a 

 closed extremity, towards the inner surface of the fibrous cover- 

 ing of the testis, and from this point it proceeds in a zig-zag 

 course towards the middle of the organ. It loses its convoluted 

 appearance when it approaches to what is called the mediastinum 

 of the testis, and, passing through its fibres, opens into the next 

 order of vessels. 



The second order of vessels is situated in the substance of the 



