606 Wisconsin Academy of Sciences, Arts, and Letters. 
ports the absence of reducing sugars. He was able, however, 
to isolate a complex carbohydrate constituent of the pentosan 
type which he called algin. The latter had been previously 
reported by Stanford^. 
The following experiments are recorded although they are 
only a preliminary survey in this direction. In several in¬ 
stances qualitative tests Avere obtained but the reaction seemed 
to indicate only traces of carbohydrates present. In view of 
the small amount of material available for examination, a de¬ 
tailed study of the carbohydrates of the fresh water plankton 
was not undertaken at this time. However, our findings are 
reported here in the hope that they may be a guide to some 
future study Avhen a favorable opportunity presents itself for 
obtaining a larger catch of these small organisms. It should 
be stated in this connection that all the investigators of ma¬ 
rine algae worked with kilograms of the material, Avhereas we 
were limited to several hundred grams for the entire study. 
Six plankton catches were examined. The Crustacea plank¬ 
ton were first extracted Avith Avater, folloAved by 95 per cent, 
70 per cent and 50 per cent alcohol respectively. The aqueous 
or de-alcoholized extract, as the case might be, Avas treated with 
basic lead acetate solution, the precipitated matter removed, and 
the excess of lead precipitated as the sulphate. The filtrate 
did not reduce Fehling’s solution either before or after inver¬ 
sion. This indicates the absence of reducing sugars. 
Following the method of the Association of Official Agricul¬ 
tural Chemists, a weighed portion of each Crustacea catch was 
distilled with hydrochloric acid. A small quantity of fur¬ 
fural was formed. It Avas precipitated Avith phloroglucinol so¬ 
lution and the resulting phloroglucid calculated to pentosans. 
Extracts of the plant catches '‘A” and “B’’ made Avith 50 
per cent alcohol and purified as above showed a slight reducing 
action upon Fehling’s solution. No osazone, however, was 
obtained Avith phenylhydrazine in acetic acid solution. A good 
precipitation of phloroglucid was obtained from the furfural 
liberated on distilling the samples with hydrochloric acid. 
The algal catch ‘‘E” and the mixed diatom-crustacea catch 
5138 were covered with Avater in large flasks. The latter were 
placed in a boiling Avater-bath for one hour and then set aside 
i Chem. News 47, 254-257 (1883). 
