72 TRANSACTIONS OF THE [nov. 13, 
remain unspread must, in their clustered condition, be inevitably 
lost. 
Aération seems to be especially concerned with three cultural 
details—(1) the character of the egg trays, (2) the mode of egg 
attachment, and (5) the means of securing water circulation. 
1. The shallow trays to which the eggs are affixed have, as 
far as the writer can find, been constr ucted either of fine metal 
gauze or of cheese cloth. In the present experiments the use 
of a coarse-meshed “ mosquito netting ” was found to give most 
satisfactory results. Ofa tray bottom of this material the per- 
forations are sufficiently large to admit an egg, but not so large 
as to permit it to pass through. <A tray bottom thus prepared 
retains a single layer of eggs which may be aérated as conven- 
iently on the under as on the upper side. 
2. In former experiments the eggs, becoming viscid, appear 
to have been lifted from the water, spread upon the trays and 
retained thus until their attachment. In trials made at the 
suggestion of Mr. Pancost, of Delaware City, the eggs were 
Spread upon immersed trays. Under water the eggs are easily 
handled, flowing smoothly over the netting tray, and by careful 
tapping of the tray frame may be made to assume a single layer. 
If placed on the tray ten minutes after fertilization they become 
ae attached in about twenty minutes. 
To assure the free circulation of water necessary to the 
natehing process, the egg trays are arranged in stout wooden 
cases, which float in the current or are sunk in deep water. Bot- 
tom and two sides of the cases covered with metal gauze permit 
a free passage of water current. In the present experiments the 
floating hatching case differed from any of which the writer is 
aware in the following regards: It was nearly as deep as wide. 
By this means the hatching trays might be placed almost verti- 
cally, to thus take ady antage of the water current and at the 
same time to economize space. As many as four trays to a case 
were successfully employed; these, held in position by cleats, 
were directed slightly downward to guard against deposits of 
sediment. The incoming current was directed against the under 
side of the tray. 
The problems of aération seem closely connected with those of 
fungus growth, as may be seen in the following paragraphs. 
Inroads of ‘Fish F ungus, Achlya.—The ereatest difficulty 
encountered by Prof. Ryder in his experiments at Delaware 
City (1888) appeared to have been due to fungus growth. This 
was found to arise at various points of the hatching tray during 
the first forty-eight hours of hatching, and to eradually spread 
its velvety encasing over and stifle the entire egg mass. For 
