Editorial Comment. 321 
As a stimulus toward special readings we have usually re- 
quired from two to four monographs or essays per term from 
each student. These essays are written on paper of uniform 
size say letter paper (loi^xS inches), consisting of four or five 
pages of reading matter and from one to two drawings illustrat- 
ing parts of the paper. The subjects assigned vai'y with the 
different divisions of geology, but more frequently deal with 
economical geology. We usually assign each student a sepa- 
rate subject and have a part of the papers read before the class. 
EDITORIAL COMMENT. 
SOME NEW CONTRIBUTIONS TO THE DISCUSSION OF CORAL 
FORMATIONS. 
Captain W. J. L. Wharton, Hydrogapher to the English 
Navy, contributes to Nature an account of some coral forma- 
tions in the China sea — a welcome addition to our knowledge 
of the facts, doubly welcome in contrast with the unseemly per- 
sonalities and recriminations growing out of the bitter charges 
made by the Duke of Argyll against English scientists. Whar- 
ton frankly avows his "abandonment of the supposition that 
subsidence plays a principal part in the production of barrier 
reefs and atolls," but at the same time is "not satisfied with one 
part of the explanation offered by Mr. J. Murray." The one 
element in Murray's theory which does not satisfy Capt. Whar- 
ton is the same which Dr. L. E. Hicks in his article, "The Reef 
Builders," in this number of this journal, regards as the weak- 
est, viz., the competency of sea water to remove, by its solvent 
action, the great masses of coral which are supposed to have 
partially filled the deep lagoons of some atolls, and the deep 
channels within certain barrier reefs. 
Referring to the very interesting and important fact ascer- 
tained by the Challenger Expedition that pelagic shells falling 
through great depths are dissolved, Wharton says that the case 
is very different from the solution of coral rock in lagoons. 
