THE REGION OF THE SPINAL CORD 399 
disappeared, the nephric organs would still remain, not as coxal 
glands, but as purely somatic excretory glands. They would still be 
homologous with the annelid segmental organs, or with the coxal 
glands, but would arise in toto from a part of the ventral ccelom or 
nephroccele, more dorsal than the former appendicular part, because 
the appendages and their enclosed ccelom are always situated ventrally 
to the body. Again, according to Sedgwick, the nephric tubules are 
Fic. 157.—TRANSVERSE SECTION OF PERIpaTUS Empryo, (After von KENNEL.) 
Al., alimentary canal; N., nerve-cord; App., appendage; J, IJ, ITI, the three 
divisions (lateral, median, and dorso-median) of the ccelom. 
Fig. 158.—Secrion or Peripatus. (After SzpGwicx.) 
Al., alimentary canal; N., nerve-cord; App., appendage; i.v., internal, and e¢.v., 
external vesicles of the segmented excretory tubule (coxal gland). 
connected with two ccelomic vesicles, the one in the appendage the 
internal vesicle, and the other, the so-called bladder, or the external 
vesicle, in the body itself, close against the nerve-cord. Sedgwick 
appears to consider that either of these vesicles may form the end- 
sac of a nephric tubule, for he discusses the question whether the 
single vesicle, which in each case gives origin to the nephridia of the. 
first three legs, corresponds to the internal or external vesicle. He 
te, 
