Ulero-gestation in Trygon Bleekeri. 423 



In any transverse section of a trophoncma we find tlie 

 vestibules of some of the glands opening widely to the surface 

 between transvcr.se sections of two superficial capillaries, 

 others issuing by narrowed openings between two more or less 

 obliquely cut capillaries, while others again end blindly, 

 being covered by a su[)erficial cai)illary in longitudinal sec- 

 tion, which itself lies beneath a layer of pavement epithelium. 



It may now be stated that the examination of numerous 

 sections made in various planes shows that the glands are 

 faintly compound, and that they consist of a collecting well 

 or vestibule, into the bottom of which the short lumina of 

 the true secreting bulbs open on all sides. 



A very delicate basement membrane delimits the glands in 

 their bulbous portion. 



The epithelium, as above noticed, is of two kinds : in the 

 bulbs it consists of large, long, broad-based tapering cells, in 

 which a single nucleus lies close to the basement membrane ; 

 in the vestibule or well we find short columnar or almost 

 cubical cells in which the single nucleus is more central. 



The nucleus stains deeply witli carmine, the rest of the 

 cell, which is faintly granular, taking the stain very lightly. 



In some of the vestibules lightly stained coagula are 

 noticed. 



There are other unimportant histological details ; but the 

 main facts which sections exhibit are that a trophonema con- 

 sists essentially of a dense vascular network, encasing in its 

 meshes simple glands with bulbous loculi, protected by a layer 

 of pavement epithelium wdiich is fenestrated over the openings 

 of the glands. The amount of connective tissue, except at 

 the very base of the trophonema, is insignificant, and the 

 trophonemata are practically built of blood-vessels and 

 secreting epithelium. 



It is not easy to make an exact estimate of the number of 

 glands borne on a single trophonema, and the following 

 calculation can only be regarded as a probable approximation. 

 Taking the area of the orifice of a vestibule at an average of 

 •001 square millimetre, and, since in any one plane at least 

 two glands open into every vestibule, assuming that the 

 space between the vestibules occupied by superficial capil- 

 laries is given up to an equivalent of vestibular orifices, and 

 calculating the glandular surface of an average trophonema at 

 22*8 square millimetres, we should get in each trophonema 

 22,800 glands. 



