METHODS OF HATCHING FISH EGGS. 
217 
Species. 
Number 
of eggs to 
a standard 
quart, 
57.75 cu. in. 
Authority. 
How determined. 
Reference. 
Spanish mackerel • 
1, 267, 728 
R. E. Earll 
From diameter 
P. C. Report, 1880, p. 450. 
335, 000 
120, 000 
36, 800 
34, 800 
July 7, ’87, Forest and Stream. 
F. C. Report, 1880, p. 575. 
Central Station, season 1884-’85. 
F.N. Clark 
Do 
Do . 
33,' 450 
28, 239 
28, 800 
do 
Central Station, Feb., 1887, 
Shat! 5 
Do 
W. P. Sauerhoif . . . 
Count of 1 gill 
Battery Station, May, 1886. 
Do. 
Do 
22i 750 
24i 363 
12, 800 
F. N. Clark 
Count, 1 duid ounce 
F. C. Report, 1882, p. 820. 
Personal letter, Wytheville 
Station. 
Do. 
Do 
9, 485 
G. A.. Seagle 
Count, 4 cubic iuches 
Rainbow trout, three and 
7, 625 
E. M. Robinson . . 
Count, 8 cubic inches 
four years old fish, domes- 
ticated. 
Rainbow trout frooi Baird, 
Cal. 
Do 
6, 875 
6, 624 
6, 536 
Do. 
Central Station, 1884. 
Do 
9i935 
8,301 
11, 092 
Central Station, Mar., 1887. 
Personal letter, Wytheville 
Station. 
Personal letter, Corry, Pa., 
hatchery. 
Central Station, Feb., 1887. 
Personal letter, Wytheville 
Do ^ 
Do. 
13, 998 
Brook trout, eegs from 
is; 590 
E. M. Robinson . . 
Count, 36 cubic inches 
Michigan. 
Brook trout, eggs from Con- 
necticut. 
12, 063 
5, 720 
5,780 
3,696 
4,272 
3, 300 
Slation. 
Do. 
Do 
Central Station, Dec., 1887. 
Do. 
* Scomberomorus uiaculatiia. 
^Gadus niorrhua. 
* Stizostedion Yitreum. 
‘‘CoregODus clupeiforiuis. 
® Olupea sapidiasima. 
® Roccus lineatus. 
^ Salmo irideus. 
* Salmo fano. 
® Salvelinus foutinalis. 
*®SalveliDU8 namaycush. 
** OncorhvDchus chouicha. 
*2Salmo vsalar. 
Salmo salar, var. sebago. 
An examination of the table will show certain apparent discrepancies between 
the counts made from year to year. It is undoubtedly true that in some kinds of eggs 
there is a slight variation from season to season. Where the count is made of a full 
quart, and of eggs matured under like conditions, the discrepancy in number will be 
but trifling. We can not expect an equality in size between the eggs from wild and 
domesticated fish, between “ scrub ” and improved ” stock. 
The McDonald jar presents an easy, quick, and safe means of applying the knowl- 
edge contained in the table. The measurements in all cases are made while the eggs 
are in the jar, and with the cap screwed down. To ascertain how many eggs have 
been lost or hatched or are on hand are questions constantly arising. It would be 
cumbersome and tedious were we obliged to open the jar and measure the eggs in a 
graduate every time such information was needed. Moreover, we have to know the 
quantity of eggs in each jar itt a period in their development when such procedure 
would be exceedingly hazardous. 
The measuring scale is a light square made of wood, not so liable to break the jar 
as metal. The long leg of the square is 15 inches long, half an inch wide, and quarter 
of an inch thick. The short leg is of the same breadth and thickness and half the 
length. (Fig. 4.) The long leg is graduated to read from the bottom upwards. The 
