466 
GEOLOGY: W. M. DAVIS 
calcium chloride a crystalline precipitate soluble in hydrochloric acid 
and reprecipitated by ammonia. 
The hydrochloric acid solution of the base, obtained by decomposing 
the water solution of the gold salt with hydrogen sulphide, gives with 
phenylhydrazine and potassium acetate at about 40° a reddish brown, 
partly crystalline, partly resinous solid, easily soluble in organic solvents 
(except ligroin), which, when dissolved in a little alcohol and poured 
into much boiling water, separates on cooling in fine felted needles 
melting at 159° when heated slowly and at 162-3° when the capillary 
is introduced into a bath previously heated to 150°. 
With the data at his disposal Abel in 1903 suggested that the base 
might well be a highly unstable cyclic compound related to the pyrazol- 
one series. In 1906 Curtius began publishing the results of his interest- 
ing investigations on the series of compounds obtained by the action of 
alkalies on diazoacetic ester,^ and our new base in so many respects 
(namely, in its decomposition into methylhydrazine, methylamine, am- 
monia and oxalic acid) so closely resembles his 'pseudodiazoacetic acid' 
derivatives that it may not appear too hazardous to suggest that it con- 
tains the isodiazome thane or N-l,4-dihydro-l,2,4,5-tetrazine grouping 
and that its constitution may be represented by the formula 
CHsNy xN.N(CH)3\ 
I ^CCHO or OHCC^ ^CCHO. 
(CHs) . W 
This suggestion is made with all reserve and it is hoped that certain 
experiments now being carried out will soon make it possible to decide 
whether or not it is tenable. 
[This work was made possible by a Grant to Prof. John J. Abel from 
the Rockefeller Institute for Medical Research.] 
lAbel, J. J., Amer. J. Physiol. Proc, 8, 31 (1903); Ber. D. chem. Ges., 36, 1846 (1903); 
37, 368 (1904); Abel and Taveau, R. deM., /. Biol. Chem , 1, 13 (1905). 
2 For a summary of the work of Curtius on these compounds, see Ber. D. chem. Ges., 
41, 3161 (1908); also Ibid., 42, 3284 (1909). 
EXTINGUISHED AND RESURGENT CORAL REEFS 
By W. M. Davis 
DEPARTMENT OF GEOLOGY AND GEOGRAPHY. HARVARD UNIVERSITY 
Received by the Academy, June 22, 1916 
In the diagrams by which Darwin originally illustrated his theory of 
upgrowing reefs on subsiding foundations, the reefs were drawn as 
growing upward and inward, in such a way that the diameter of their 
