Lymphatics in Small Intestine of the Pig. 



95 



is connected with the thoracic duct through the cistema chyli. Such 

 an injection is shown in Fig. 1 from an embryo 3 cm. long. The 

 earliest stage in which the thoracic duct and sac have been injected 

 is 2.7 cm., where the appearances do not differ from the specimen 

 shown in Fig. 1, except that the sac is a little smaller. 



Fig. 1. — Au embryo pig 3 cm. loug, to show an injection of the lymphatics 

 made by puncturing the thoracic duct, x 2.5, R. o., reproductive organ ; r. s., 

 retroperitoneal sac ; s., stomach ; s. b., suprarenal body ; t. d., thoracic duct 

 around the aorta ; W. b., Wolffian body. 



The method of injection is as follows: the embryo is opened by 

 cutting away the thoracic wall and turning the left lung far to the 

 right or removing it entirely. For injections of the retroperitoneal 

 sac it is better to remove the liver. The aorta and azygos vein 

 should be thoroughly exposed, and the hypodermic needle plunged 

 down behind the aorta, inserting the needle just at the arch where 



