92 



Acad. Sc. Paris. T. 123. 1896. p. 1314), Abelous and Biarnes 

 (CR.Soc. Biol.T.49. 1897. p. 175 and 249) and P or tier 101) 

 have shown. In Robert's paper I found an indication, that 

 the latter author had found them in Echinoderm blood ; unfor- 

 tunately I was not able to consult the original paper. 



What their exact function is in all these groups, nobody caij 

 tell. We can not say, whether the catalases serve only as im- 

 mune bodies against the highly toxic hydrogen peroxyde — 

 toxicity due to the fact that it causes air embolisms — , as 

 Oskar Loew supposed (Catalase. U.S. Deptm. of Agriculture. 

 1901. Rep. No. 68. After Robert), or whether the peroxide- 

 theory of A. Bach (Du role des peroxydes dans les pheno- 

 menes d'oxydation lente. C.R. Acad. Sc. Paris. T. 124. 1897. 

 p. 251) and of Engler and Wild (Ueber SauerstofF-activie- 

 rung. Chem. Ber. Jahrg. 30. 1897. p. 1669. Both after Robert) 

 holds true. The latter theory assumes the formation of peroxides 

 as the primary stage in every combustion of organic substances 

 in the living organism and their destruction by catalase. It is 

 certainly not a measure for metabolic activity, according to 

 Morgulis 88). 



Note. 1 . The so called melanosis in the blood of catterpillars etc. has also 

 been supposed to be due to peroxydases. Here we surely have to do with 

 a tyrosinase according to Biedermann 8). 



2. The results of P o r t i e r who found oxidases to be present nearly 

 everywhere have partly been denied by Kobert. For this reason 

 a repetition of his work does not seem superfluous. 



c. Contents of the Polian vesicles of Thyone. Importance 

 of the water vascular system in respiration. 



The writer 60) was struck by the brilliant red color of the Polian 

 vesicles of Thyone each time that he dissected a specimen. 

 Curiosity drove him to examine this phenomenon a little more 

 closely though it did not seem to have any direct bearing on 

 the problem in hand. 



In Thyone briareus these vesicles which form as we know 

 a part of the water-vascular system, are present in numbers 

 varying from one to four. Scott 118) has studied their anato- 

 mical relations a little more closely and just in this particular 

 species. He finds that usually one is present, often two, 

 occasionally three and rarely four. The general tendency for 

 them is to go to the left side, and thus to disturb the bilateral 

 symmetry. The retractor muscles of course vary with the 

 number of the Polian vesicles. In size as well as in number 

 there is a considerable variety. 



The Polian vesicles form, as mentioned above, a part of the 

 water vascular system and therefore they are on the one hand in 

 connection with the ambulacral feet, which are found all over 

 the outside of the body. At the inside of the muscular body 



