242 



NORMAL HISTOLOGY. 



FIG 



Human milk : A , usual appearance ; 

 B, shortly after delivery ; a, large colos- 

 trum corpuscle ; b, small amoeboid cells 

 containing oil ; c, colostrum-corpuscles 

 with few oil-droplets. 



suspended. These globules do not coalesce, owing to the probable 

 presence of a delicate envelope of casein. The addition of acetic 



acid or of caustic potash destroys the 

 envelope and liberates the oil-droplets, 

 which then run together, forming ir- 

 regular masses. Human milk is usu- 

 ally alkaline. 



The milk secreted during the first 

 few days after delivery contains 

 large fatty granular - looking bodies 

 known as colostrum - corpuscles ; 

 these bodies probably represent the re- 

 mains of a portion of the epithelial cells 

 which at one time occupied the centre 

 of the then solid acini, but which underwent fatty degeneration and 

 partial destruction on the establishment of lactation. 



The development of the reproductive organs comprises the 

 genesis of two distinct parts, the sexual glands and their excre- 

 tory ducts. 



In order to understand the formation of the reproductive organs 

 it is necessary to recall the condition of the fcetal excretory structures 

 prior to the appearance of the sexual glands, since the Wolffian body 

 and its duct play important roles in the subsequent development of 

 the generative tract. The Wolffian body consists essentially of a 

 long tube, the WolfHan duct, which extends parallel with the ver- 

 tebral axis throughout the lower part of the body-cavity, and of the 



transverse Wolffian 



FIG. 279. tubules, which join the 



duct generally at right 

 angles, so that the two 

 parts of the Wolffian 

 body are frequently 

 compared to the back 

 and the teeth of a comb. 

 The tubules are tor- 

 tuous, and bear close 

 relations with tufts of 

 convoluted capillary 

 blood-vessels, much the 

 same as the uriniferous 

 tubules do in the Mal- 

 pighian bodies of the 



kidney. Some time after the establishment of the Wolffian body and 

 its duct, a second canal, the Miillerian duct, makes its appearance ; 



Section of rabbit embryo of ten and a half days, showing the 

 Wolffian bodies and the early indifferent sexual glands; w, t, 

 and m, respectively duct, tubules, and Malpighian corpuscle 

 of Wolffian body ; /, mesothelial surface of primary peritoneal 

 cavity ; g, indifferent sexual glands. 



