780 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 



content ranging from .20 per cent in Enteromorpha to .98 

 per cent in Porphyra. 



RELATION OF THE ALGAE TO NITROGEN 



Some of the recent work on pure culture methods with 

 fresh-water algae, such as that of Beyerinck ('90), Charpen- 

 tier ('03, '03 a ), Chick ('03), Artari (»13), Spargo ('13), and 

 Schramm ( '14) have conclusively proved that these forms can 

 utilize organic nitrogen. Furthermore, the work of Letts and 

 Hawthorne ('11), and Foster (M4) point to the fact that the 

 marine forms may have this capacity as well. Letts and Haw- 

 thorne and also Letts and Richards ('11) showed that Viva 

 latissima grew better in sewage-contaminated sea-water than 

 in water from the open sea. Foster placed strips of Viva 

 lactuca in normal and artificial sea-water, containing in addi- 

 tion compounds of nitrogen in varying concentrations. When 

 urea or ammonium sulphate was added to either solution an 

 accelerated growth took place. 



The current conception concerning the assimilation of 

 organic nitrogen by the animal organism is that the protein 

 and amino acid molecule must be completely desamidized be- 

 fore the building-up process can begin. In the absence of 

 definite information to the contrary, we can conceive of a par- 

 allel situation existing in the plant. The question at once 

 arises in regard to the algae, whether this be due to the agency 

 of amidases formed by the tissue, or to the activity of desamid- 

 izing bacteria, the presence of which Brandt ( '99), Gran ( '02), 

 Baur (>02), Reinke ('03), Benecke and Keutner ('03), and 

 others have shown to exist abundantly in harbor waters. 

 Neither Letts and Hawthorne nor Foster worked with pure 



cultures, and these bacteria may have been the agency in their 



experiments to render the amino-nitrogen assimilable. 



CARBOHYDRATES AND CARBOHYDRATE CLEAVAGE PRODUCTS OF 



ALGAL SLIME 



Besides the carbohydrates that may be directly assimilable, 

 we find those whose function in metabolism is more or less 

 disputed. The so-called algal slime is made up chiefly of such 

 products. 



