372 



The entire gland varies in size according to the size of the 

 embryo, while its shape varies very slightly. This variation in size, 

 however, does not show any constant proportion to the size of the 

 body, as will be seen from the following table: 



Length of the Body. Length of the Gland. 

 175 mm 29 mm 



187 „ 37 ,, 



260 „ 95 „ 



From the above table, it is clear that the gland increases in size 

 with the age of the embryo. How long this growth continues I do 

 not know at present. The gland was obtained also from embryos 

 having a body length of 75 mm, and 95 mm respectively, but owing 

 to a very poor preservation of the material, an exact measurement 

 was not made. 



The gland preserved in alcohol or in formalin shows, in most 

 parts, a yellowish-brown color, while some parts of the gland, especi- 

 ally along the lateral border, present a greyish tinge. Microscopical 

 examination reveals the fact that the cells in such a greyish area 

 contain a large number of fine needle-like crystals (fat precipitation?). 



The anterior half of the gland is composed of polygonal lobules 

 as in other known glands (for example, glandula parotis). In the 

 posterior portion the lobules owing to the confined space in which 

 they are found, are much flattened and arranged in such a way that 

 the base of one lobule is overlapped by the free edge of another. 



The entire gland is surrounded by a thin fibrous capsule which 

 penetrates the substance to divide it into the lobes and lobules. The 

 gland is composed of the two entirely diö'erent constituent tissues; 

 an outer fat tissue and an inner lymphoid structure ; that is, an inner 

 lymphoid structure is completely surrounded by the fat tissue. To 

 be more precise, the gland is composed of a large number of lym- 

 phatic nodules, each surrounded by a thick fibrous capsule, and each 

 of them or several of them, are again surrounded by the fat tissue. 

 In some cases, the fat tissue and lymphoid structure are found in 

 the same fibrous capsule. 



The lymphatic nodules are composed of adenoid tissue which 

 contains an abundant supply of blood and lymph sinuses and vessels. 

 A large number of leucocytes of various sizes can be seen within the 

 adenoid tissue. The lymphatic nodules do not show a definite area 

 of germination and consequently the mitoses of the cells can be seen 

 almost everywhere throughout the gland. 



The gland has an abundant supply of non-medullated nerve-fibers. 



