[25] THE SPANISH MACKEREL. 419 
though not always, takes place in the absence of spermatozoa, but in 
such cases the action is slower and the membrane is never expanded to 
its fullest extent. By this slighter expansion, as well as by the greater 
delicacy of the membrane, the spawn-taker usually knows that the eggs 
have not been properly fertilized. 
The mackerel were examined as soon as they were taken from the 
pounds, and when ripe females were secured they were at once “stripped,” 
and owing to the abundance of ripe males no difficulty was experienced 
in getting milt for impregnating them. As the pounds were some dis- 
tance from the harbor, the eggs were carefully tended during the journey 
to the wharf, clean water being added every half hour to keep them in 
good condition. 
It was at once seen that the eggs of the mackerel, like those of the 
cod, belonged to the class known as floating eggs, as after impregnation 
most of them floated at the surface, though a few remained suspended 
in the water at different depths, while others sank slowly to the bottom. 
When, however, there was the least current they were readily carried 
about by it, and became generally distributed throughout the liquid. 
A small oil-globule was noticed in each egg. This served to keep the 
egg in position, remaining constantly at its upper surface, while the fish 
formed with the curve of its back at the lowest point directly opposite. 
As the eggs were only a 22d to a 28th of an inch in diameter and per- 
fectly transparent it was difficult for one not accustomed to handling 
them to detect their presence, and it was not at all surprising that the 
fishermen had never noticed them floating on the surface of the bay. 
In fact, had their attention been directed to them, they would probably 
have had no idea of what they were. 
The number of eggs capable of impregnation that can be taken from 
a female at one “stripping” varies, with the size and condition of the 
fish, from 25,000 to 100,000, this being ,but a small portion of the num- 
ber actually contained in the fish; for, as has been said, the eggs ripen 
very irregularly, some being fully deveioped while others are still green. 
As soon as an egg has reached maturity it frees itself from the envelop- 
ing membrane and passes down through the proper duct, and is soon 
excluded from the fish, to make way for others. Thus the spawning 
season for a single individual probably lasts for more than a month. 
The fish from which eggs were taken by me were so roughly handled 
that few survived the operation, though with proper care it seems prob- 
able that they could be penned up and “stripped” from time to time, 
until a greater part, if not all, of the eggs were secured. The mackerel 
is, however, a delicate fish, and the question of penning and handling it 
is by no means settled. 
Our experiments with the eggs of the codfish had given us some 
experience in the treatment of floating eggs, which proved very valuable 
in suggesting the proper kind of apparatus to be used at this time. On 
reaching the harbor the eggs were allowed to remain in the pans until a 
