46 HAROLD SEUERS COLTON. 



and Lefevrc ('98) ha\e agreed that ii probably serves an ab- 

 sorbing function, something like tin gastrovascular canals of 

 C.elentcrata. Huxley ('51) asked: "Does this tubular system 

 represent a hepatic organ or is it not more probably a sort of 

 rudimentary lacieal -\ stem a means of straining off the nutri- 

 tive juices from the stomach into the blood by which these tubes 

 are bathed ?" It is very probable that the organ has a digestive 

 function ; there seems strong evidence to support that idea. But 

 the direction of the cilia in the duct would forbid the conclusion 

 of Huxley, etc., that the function is that of absorption. 



There is yet another function that lias been attributed to the 

 pyloric gland. Kowalewsky ('74) was inclined from what he 

 knew of the structure of the organ in Peropora to attribute to 

 it urinary functions. 



Krunkenberg ('80) says: "Ich finde sie als constantes, durch 

 die Murexideprobe leicht und schon nachzuweisendes Product 

 der als Xieren angesprochnen driisigen Darmanhange bei Phal- 

 litsia mentnla." This statement is based on a misconception. 

 He did not distinguish that the pyloric gland and the renal 

 vesicles were not part of one system. What he analyzed were 

 the concretions which others have found to contain uric acid. 

 This interpretation is supported by the fact that he could not 

 find uric acid in the gland of Ciona and of Cynthia, neither of 

 which have renal vesicles covering the intestine. 



In SaJpa, Todaro ('oi-'o2) described three pairs of diverticula 

 from the alimentary canal that had the power of taking up car- 

 min. The first pair was in the pharynx, the second pair in the 

 oesophagus and the third pair the pyloric gland. 



Let us now turn and inquire as to what organs have been pre- 

 viously described as possessing the power of elimination of waste 

 products of metabolism from the body of tunicates. Roule ('84) 

 make- ihe di-t inction bet \\eeii a kidney of excretion and one of 

 accumulation. Through the investigations of Van Beneden ('46), 

 Kupffer ('72), Laca/e-Duthiers ('741, Ko\\alc>\ ky ('89) and Dahl- 

 griin ('oo), we have a knowledge of this latter type of organ at 

 least in a lew groups. The kidney accumulation may be said 

 to COM^JM of i wo t> pe-. In .^nl/Mi, ( 'i<ia and Botryllns it consists 

 of blood cells containing brownish concretions. The second t\ pe 



