1900-1901.] Prof. Letts and Mr Hawthorne on Ulva latissima. 279 
The composition of the tissues of Ulva latissima deduced from 
the preceding analysis is — 
Carbon, . . . . 35 T 5 
Hydrogen, . . 5 ‘27 
Nitrogen, . . . 6T8 
Oxygen (by difference), . 38 "33 
Ash, .... 15-07 containingj j r ^ hur ’ * g-20 
100-00 
Proximate analysis. — The attempts which we have made to 
isolate any definite compounds as proximate constituents of the 
ulva have not been very successful, but it is only fair to ourselves 
to say that we have not had time to study the matter exhaustively. 
Various experiments were tried with different solvents. 
When boiled with water the seaweed does not soften nor suffer 
apparently any considerable change, and no blue colour is produced 
when the infusion is treated with iodine. 
A special experiment was made to ascertain whether any carbo- 
hydrate was present capable of ready hydrolysis into a sugar, and 
for this purpose a quantity of the washed ulva was treated for a 
week in the cold with water containing 5 per cent, of sulphuric acid. 
The extract was then drained away from the seaweed, excess of 
barium carbonate added, the solution filtered and evaporated. 
During the evaporation, white amorphous matter separated and 
oily globules also. The dried residue was treated with a little 
water, the solution filtered and heated on a water-batli with 2 grms. 
of crystallised phenyl-hydrazine hydrochlorate, and 3 grms. of 
sodium acetate, but no trace of a crystallised osazone could be 
obtained. For the sake of comparison, a mixture of 1 grm. of 
ordinary dextrose with the same quantities of phenyl-hydrazine 
hydrochlorate and sodium acetate and water was heated and gave 
abundance of the yellow osazone. 
The amorphous matter turned out to be magnesium carbonate, 
with practically no organic matter. 
The remainder of the ulva , after treatment with acid, was well 
washed with distilled water, and then digested in the cold for a 
week with 5 per cent, caustic soda solution. The resulting brown 
