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 40x2 cm., and the inner being 5 mm. in diameter. 

 The lower end of this 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 cc. 

 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 HC1 

 or NaOH. In the formaldehyde titrations 10 cc. of the sub- 



