40 



Cohnheim discovered that the only substance present in 

 the perivisceral fluid and more than in the sea water, is a sub- 

 stance which gives a precipitate with phosphotungstic acid. It 

 is not arginin or any other amino-acid (no precipitate with AgNOs), 

 since as we saw above none of these are present. Is this perhaps 

 the same substance? Phosphotungstic acid in fact precipitates 

 uric acid (Carl Oppenheimer. Handbuch der Biochemie. 

 Jena. Gustav Fischer. 1909. Bd. I. p. 625). 



He also found slightly more N in the perivisceral fluid of 

 our animals than in the sea water, as the following table shows : 



Table 6. After Cohnheim. 



100 c. c. sea water (Kjeldahl). 

 100 c. c. Holothuria „blood" . 

 100 c. c. urchin „blood" . . . 



0.4 mgr. N, 

 2.5 mgr. N. 

 5.7 mgr. N. 



He was unable to explain such excess of N ; possibly it is, 

 at least partly, due to uric acid. 



M our son and Schlagdenhauffen found urea in the 

 perivisceral fluid of Strongylocentrotus lividus. Brandt and 

 Toxopneustes lividus. Lacken in a concentration of 0.010 "/q— 

 0.013 "/b. I have not been able to detect any by means of 

 Nessler's reagent after hydrolysis (see also the results of 

 Griffiths in chapter 23 and remember the scarcety of urea in 

 lower animals). They also find a ..ptomaine ')" present which 

 has a toxic action on frogs. The same ptomaine is also found 

 between the shells of bivalves. Whether or not our substance 

 is meant here, the present writer does not dare to decide. 



The occurrence of uric acid in the perivisceral fluid of the 

 Echinoderms is very interesting, because it may throw a hght 

 on the dark problem of their excretion. I refer to chapter 23 

 for this topic. 



All the tests mentioned above have been made on Asterias, 

 Arbacia and Thyone with the same result. We see that in 

 these representatives of the chief groups of the Echinoderms, the 

 coelomic fluid is really nothing much more than sea water in 

 which almost constantly a small quantity of uric acid is present 

 and occasionally some of the products of hydrolysis of the 

 food, depending on the feeding conditions. 



A fairly constant blood picture is only characteristic for the 



') I do not understand what these authors mean here. Ptomaines are as 

 far as my knowledge goes, basic substances, products of bacterial decomposition 

 of protein, such as cadaverin and putrescein. I can not concieve how such 

 substances present only in decaying material and highly toxic for every living 

 organism, should be found in the „blood" of the representatives of this group. 



Since however uric acid has some reactions in common with these substances 



the authors do not indicate which test they have used — it is possible that 

 this might be the explanation. 



