475 
were arrayed from river margin near the mark of low water out to 
near the channel, the eggs of marginal waters speedily died while 
those of deep water in large part (90—95%) were safely hatched. 
The arrangement of the eggs in thin layers, moreover, was found 
a condition necessary for aeration. This mode, unfortunately, is not 
easily attained. ‘The eggs soon after fertilization become viscid, and 
unless speedy care be given will shortly glue together in a dense jelly- 
like mass. Of this the inner and poorly aerated eggs speedily die, and 
their disintegration appears to cause the destruction of all. It is 
clear, therefore, that in the disposition of the adhesive eggs upon the 
hatching trays the greatest promptness is required. As a detail of 
this process the eggs were found to be most conveniently spread when 
under water: a mass of eggs placed upon the submerged tray a few 
minutes after fertilization is readily to be floated out into a single 
layer, and may thus be held till attached (about 20 minutes later). In 
the experiments of the writer the most favorable material for tray bot- 
tom proved to be a coarse mosquito netting. On this a single layer of 
eggs was easily arranged, the meshes of the netting proving sufficiently 
large to allow eggs to enter and become favorably attached, but not 
large enough to allow the eggs to pass through: a well prepared tray 
bottom thus received on either side the best conditions for aeration. 
Floating hatching boxes with bottom and ends of fine metal gauze 
were found to give satisfactory results. Space was economized by 
making the box a deep one, placing the hatching trays almost verti- 
cally, allowing four or five to a box. If the trays be slightly inclined 
downward against the direction of the current they are naturally less 
apt to suffer from deposits of silt. 
Under natural conditions the hatching of eggs took place (water 
temperature 60°—73° F.) between 92 and 100 hours. 
4. Laubfrosch und Wetter. 
Von R. v. Lendenfeld (Czernowitz). 
eingeg. 4. November 1893. 
Ich habe diesen Herbst in der Zeit vom 25. Juli bis zum 18. Oc- 
tober zehn Hyla-Exemplare zu dem Zwecke gehalten und beobachtet, 
um zu eruieren ob und in welcher Weise das Auf- und Absteigen der 
Laubfrösche durch meteorologische Verhältnisse beeinflußt wird. 
Den Fröschen wurde eine zehnsprossige Leiter gegeben und die 
Nummern der von unten nach oben 1 bis 10 bezeichneten Sprossen 
mit der Zahl der auf ihnen — oder in gleicher Höhe am Glas — 
sitzenden Frösche multipliciert; diese Zahlen wurden addiert und ein- 
