602 Wisconsin Academy of Sciences, Arts, and Letters. 
Reported by 
Source 
Nitrogen 
Stadeler (i). 
Astacus fluvi- 
atilis. 
6.14% 
7.40 
5.59 
7.00 
7.37 
6.01-6.39 
6.17 
8.22 
7.22 
6.03 
6.66 
Butschli (2)..... 
Lelman (2)... 
Ledderhose C* * > ...... 
Crustacea. 
Krukenberg (^) ... 
cuttle fish (?).... 
Araki (i) ... 
Gilson (1)... 
Iwanoff (2) .. 
Offer (*)....... 
Scholl (i») . 
Boletus edulis... 
crab shells. 
Brach (n)... 
Total sidpliur. Total sulphur was determined in six catches. 
The sample under examination was fused with sodium carbonate 
and sodium peroxide in a nickel crucible over an alcohol flame 
according to the method of the Association of Official Agricul¬ 
tural Chemists.^^ From the acidified solution of the fusion 
product sulphur was precipitated in the usual manner. Very 
interesting data were obtained in that the sulphur content of all 
six samples, three of them of plant origin and three of animal 
origin, is practically a constant. 
Since the sulphur content was constant for these test catches, 
two others of the larger series which had been collected pre¬ 
viously were examined. Catch number 112 was taken August 
4-7, 1913, from Lake Mendota. The vegetable material pre¬ 
dominates over the animal matter. Catch number 168 is a 
plant scum from Lake Mendota collected on July 11, 1914. 
The apparent constancy of the sulphur content of the plankton 
of Lake Mendota will be investigated further and samples col¬ 
lected since the summer of 1911 will be examined. 
The content of sulphur is recorded below: 
^Ann. Chem. Pharm. Ill, 21 (1859). 
2 Med. Centralbl. 1.3, 588 (1875). 
3 Abderhalden’s Biochem. Handlexikon 2, 527 (1911). 
*Z. physiol. Chem, 2, 213-227 (1878). 
^Z. Biol. 22, 480 (1887). 
«Z. physiol. Chem. 20, 498-510 (1885). 
Comp. rend. 120, 1000 (1895). 
® Beitrage Chem. Physiol, u. Pathol. 1 , 524 (1902). 
»Biochem. Z. 7, 117-127 (1908). 
^oMonatsch. 29, 1023-1036 (1908). 
Biochem. Z. 38, 468-491 (1912). 
12 U. S. Dept. Agr. Bur. Chem. Bull. 107, 23 (1912). 
