ORIGIN OF THE GLANDS. 



267 



true glandular skeleton, as it has been described in speaking 

 of the conformation of the glands. Would we follow this 

 generation of 

 the glands 

 step by step, 

 a gland must 

 be chosen in 

 which the ra- 

 mifications of 

 the excretory 

 duct can be 

 seen amidst 

 the clearer 

 blastema, 

 from the sim- 

 ple rudiment 

 to the term of 

 extreme com- 

 plexity. In 

 young em- 

 bryos of the 

 sheep (fig. 



2/4) we can, by the aid of 

 duct of the parotid still 

 simply branched, the seve- 

 ral branches enlarged like 

 buds at their extremities, 

 and but seldom divided. 

 The same thing may be seen 

 in small human embryos 

 (fig. 276). To follow the 

 onward evolution, embryos 



v 



successively more and more 

 advanced mustbe procured, 

 and, the parotid being re- 

 moved, it is to be examined 

 with a low power and as an 

 opaque object (fig. 277). 

 The clearer blastema of the 

 gland now appears dark, 

 and the excretory duct, 



Fig. 273. "Ramifications of the bronchi from the 

 embryonic Falco tinnunculns, to show the way in wh>cn 

 they sprout as blind canals. Both figures are magnified 

 about 150 times. 



a simple lens, see the excretory 



Fig. 274. Rudiments of the parotid 

 gland in the embryo of a sheep, two 

 inches in length magnified. After 

 M Oiler. 



