152 
BOTANY: CROCKER AND GROVES 
rupting its fringing reefs; this is taken to mean that earlier fringing 
reefs were drov/ned by rapid submergence, so that they did not grow 
up in off-shore barrier reefs. 
The Great Barrier reef of AustraKa, the largest reef in the world, 
with a length of some 1200 miles and a lagoon from 15 to 70 or more 
miles wide, has grown upward during the recent subsidence by which 
the Queensland coast has been elaborately embayed, as was pointed 
out by Andrews in 1902. 
Five islands of the Society group exhibit unequivocal signs of recent 
submergence in their intricately embayed shore lines, as has lately been 
shown by Marshall; the cliff-rimmed island of Tahiti, the largest and 
youngest of the group, has suffered moderate submergence after its cUffs 
were cut, but its bays are now nearly all filled with delta plains; hence a 
pause or still-stand has followed its latest submergence. All the barrier 
reefs of this group appear to have been formed during the recent sub- 
mergence, due to regional subsidence, that embayed their central islands. 
A METHOD OF PROPHESYING THE LIFE DURATION OF SEEDS 
By William Crocker and J. F. Groves 
DEPARTMENT OF BOTANY, UNIVERSITY OF CHICAGO 
Presented to the Academy, January 15, 1915 
Seeds that will withstand drying in the air without injury retain 
their viabihty under herbarium conditions from one to one hundred and 
fifty years. Seeds that will not withstand drying in the air generally 
have a longevity of only a few months. Ewart^ has suggested that seeds 
retaining their viability for three years or less be called microbiotic; 
for three to fifteen years, mesobiotic; and for more than fifteen years, 
macrobiotic. The cause of the loss of viability with storage has been 
a subject of considerable study. Two explanations have been offered: 
exhaustion of stored foods and degeneration of digestive and oxidizing 
enzymes. Both of these explanations have proved incorrect for both 
foods and enzymes are present in almost full force for some years after 
viability is lost. Certain facts have led us to surmise that the gradual 
loss of viability with storage is due to a slow coagulation of the pro- 
teins in the plasma of the embryo. The fall of longevity with rise of 
temperature and of moisture content of the seed indicate this. 
Certain known facts concerning proteins make the experimental 
investigation of this hypothesis possible. Chick and Martin^ have 
