[Vol. 2 



824 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



one of the forms falling within the scope of this study, experi- 

 ments were carried on to determine the presence or absence 

 of nucleases in one representative of each group, Ulva, Ce- 

 ramium, and Ascophyllum. 



One-half per cent nuclein was dissolved in N/10 NaOH, 

 the complete solution of the compound being shown by a 

 drop of phenylphthalein. One hundred cc. of this neutral 

 solution were added to each flask together with 3 grams of 

 air-dried algal powder. Toluene was added as an antiseptic. 

 Checks were set up by adding autoclaved algal powder to the 



nuclein and also by using nuclein solution alone. The flasks 

 were placed at 35-36° C. for 38 days, at the end of which time 

 the phosphoric acid split off was determined as P2O5 by the 

 uranium-acetate method. 1 Five cc. of a sodium acetate solu- 

 tion 2 were added to 25 cc. of the nuclein substrate, this brought 

 to a boil and titrated while hot. Potassium ferrocyanide was 

 used as an indicator — a drop of the titration mixture being 

 removed from time to time and brought into contact with a 

 drop of the indicator on a porcelain plate. The results ob- 

 tained are given in table xvhi. 



TABLE XVIII 



THE ACTION OF POWDERED TISSUE FROM CERTAIN ALGAE UPON NUCLEIN 



Substrate 



100 cc. 

 1 per cent 



Weight algal powder 



FreeH,P0 4 as P2O5 

 in 100 cc. in 38 days 



mgms. 



Net amount 

 P2O5 in 100 cc. 



mgms. 



Nuclein 



3 gms. Ceramtum 



3 gms. Ceramtum boiled 

 3 gms. Ulva 



3 gms. Ulva boiled 



3 gms. Ascophyllum 



3 gms. Ascophyllum bid. 



70.00 

 13.75 

 56.70 

 17.50 

 17.25 

 16.90 



56.25 



39.20 



.35 



These findings substantiate those of T 



('12) re- 

 ae. The 



garding the general presence of nucleases in the algae, 

 values for Ceramium agree verv well with those he obtained 



C 



c 



Ulv 



for the same form, i. e., 56.25 milligrams in 38 days at 

 compared with 76.6 milligrams in 51 days at 22-26 ( 



1 The standard solution of the uranium acetate contained 8.8052 grama of the 

 salt in 250 cc. of water, and each cc. by calculation was equivalent to 5 milligrams 



of P0O5. 



2 The sodium acetate solution contained 25 grams of sodium acetate and 25 

 cc. of 30 per cent acetic acid in 250 cc. 



