BULLETIN OF THE UNITED STATES FISH COMMISSION. 61 
which young fish resembling gurnards emerged, and he correctly con- 
jbluded that the ova of the gurnard followed the same habit as those of 
the cod and haddock. 
| The impetus given to such observations by the energetic action of 
(the United States Fish Commission enabled the Americans to corrobo- 
rate the discovery of the Norwegians in regard to the floating of the 
|ova of the cod, which lately have been artificially hatched on a some- 
what extensive scale on their coasts. The labors of Prof. Alex. Agassiz 
in the same country have further added to our knowledge of floating 
eggs, showing that the number of fishes in which this occurs is con- 
siderable. Thus the majority of the American flounders, certain kinds 
of wrasses ( Gtenolabrus ), a species of smelt ( Osmerus ), several species 
l of Coitus , the cod, haddock, gurnard, shad, mackerel, and Spanish mack- 
| erel, a kind of dory ( Zeus ), and the frog-fish are among those which have 
floating eggs. The late Dr. Malm, of Gothenburg, further increased the 
list by discovering that the eggs of the plaice were similarly buoyant; 
and G. Brook has recently added to this category the eggs of the lesser 
weever. The very great influence which this floating of the tiny eggs 
exercises on the multiplication of the food-fishes will be apparent as 
the subject is further examined. 
On the other hand, most fresh- water fishes (except the shad) deposit 
their eggs on the bottom, like the salmon, or on water plants, like the 
carp and pike; while other marine species, such as the herring, sprat, 
lumpsucker, and bimaculated sucker, follow a similar method. The 
number of marine fishes which are supposed to deposit their eggs on 
the sea bed is yearly diminishing, while the ranks of those in which the 
ripe eggs are found to float correspondingly increase. 
To come now to our own shores, and to confine our, remarks to what 
is really the most important group of fishes, namely, the food-fishes, we 
find that early in spring the surface of the sea over the great fishing- 
banks (such as Smith Bank, off the northeast of Scotland, off Caithness), 
presents vast numbers of floating eggs of food-fishes, together with 
multitudes of the very young fishes provided with a yelk-sac, exhibiting 
various degrees of absorption. Some of the ova (as those of the had- 
dock and gurnard) are larger than those of the cod, but they are few in 
number ; while those of a fourth kind are smaller than any yet men- 
tioned. When placed in a vessel of sea- water the eggs persistently 
float on its surface, descending but a very little when the jar is rudely 
shaken. Even after a protracted journey only the dead eggs roll on the 
bottom of the vessel, while all the floating eggs are living. Moreover, 
the eggs were removed from the cod itself and carried from Smith 
Bank to the marine laboratory at the harbor. On arrival, these floated 
at the surface of the vessel. On transfering them to a large jar and 
turning on a tap of sea-water a great change occurred. The ova in a 
few minutes lay on the bottom. Microscopic examination subsequently 
showed that the edge of the germinal area was disintegrating, free pro- 
