1915] 
DAVIS—ENZYME ACTION IN MARINE ALGAE 815 
at least where suction instead of compressed air is employed 
in the air method. The results with the air current were very 
often below the theoretical. The distilling tubes used were 
made in the laboratory from glass tubing, the outer jacket 
measuring 402 cem., and the inner being 5 mm. in diameter. 
The lower end of tkis latter, where it dipped into the collec- 
tion acid, was fitted with a larger tube 14 mm. in diameter— 
this to prevent a back flow of the acid; to the upper end of 
this inner tube was attached a safety bulb made from a 10 ce. 
pipette, and this in turn fitted into the Jena tube containing 
the distilling mixture, by means of a two-hole rubber stopper. 
Through the second hole in this stopper was a small piece of 
glass tubing closed at the upper end with a bit of rubber 
tubing and a pinch clamp; it was through this that the alkali 
was added after the apparatus was connected up for dis- 
tillation. 
Considerable trouble was experienced at first with bump- 
ing, especially after the digestion mixture had become con- 
centrated. Neither bits of glass nor pebbles would overcome 
it. Finally the expedient was adopted of using short pieces 
of glass tubing sealed at one end and this end placed upper- 
most. These were of such a diameter that after digestion, 
the digestion mixture drawn up into them by the cooling of 
the contained air, would easily drain out when the boiling tube 
was forced up on the side of the test-tube by a quick down- 
ward motion. 
The action of Enteromorpha, Mesogloea, and Chondrus 
powder upon various proteins—Fifty cc. lots of casein, 
legumin, albumin, and peptone were used as substrates in this 
series—all in 1 per cent concentrations. The albumin and 
peptone were dissolved directly in distilled water, the legumin 
and casein in N/10 NaOH. Two grams of air-dried tissue 
powder were used for proteolytic action, with the exception, 
however, of Mesogloea, which, as before stated, was partially 
dehydrated before being air-dried. The various substrates 
were made neutral by the addition of N/10 alkali and then 
acid or alkaline by further addition of 2.5 cc. of N/10 HCl 
or NaOH. In the formaldehyde titrations 10 ec. of the sub- 
