464 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [38] 
3.56 per cent. And still the great increase of the salmon fisheries in 
Holland during March and April, and near Basel from May to July, 
shows, without a doubt, that among the July and August salmon there 
must be many new immigrants, which is also indicated by the differ- 
ences in the degree of maturity. 
TABLE XIV.—Female winter salmon from the Rhine, near Basel. 
~*~ Wo 
= a8 BE 
& a) 8 
re ai aoe: 5 
a= : oe eh 
5 ‘=| bp 2a 
Slo eunlae ees ne 
Date. = eo By ot ae 
E 5 5 a ¥ 
a 4 =| | eee alemes 
| &D oo a. ® 
| 8 o ONS b0 a 
A | A 
December 10, 1877 .--- 875 10, 200 9, 190 1, 010 
January 30, 1878 .--- 878 11, 200 9, 190 2,010 
November 9, 1879... 907 11, 210 10, 233 977 
November 16, 1879. - 870 10, 140 9, 190 950 
November 25, 1879. - ae 888 10, 880 9, 790 1, 090 
March) 1318802 <2 33-26 ee epee aS 885 10, 860 9, 790 570 
March t20 C1880): aaciecoe este ecies secre amare eleinciniteelseiesie eh 884 9, 620 9, 190 430 
March, 20. LOs0se-< 6.08 Sere kat fetec whe aie Se eee ee | 897 | 10,090! 10,044 46 
PRTC DN 1680 be ae scence eer tee ett ry ines eee me | 885 | 10, 950 9, 190 1, 860 
Average difforenGes st... <sccciesce ceiieseossteece esceise eaten ie a oa | 994 
| 
In other words, the winter salmon and the early spring salmon are fish 
which, to begin with, have brought a larger amount of fat from the sea 
than the summer salmon. They need not, therefore, as Barfurth thinks, 
return to the sea, but their condition permits them to starve half a year 
longer. In view of these differences, the similarity (as to leanness) 
of the spawning salmon is very singular, as is (ignoring the rare late- 
comers) the relative constant difference between the amount of albumen 
and fat as compared with the greatly varying differences of the sum- 
mer salmon. The lowest figures correspond to those fish which have al- 
ready spawned, and which in consequence begin to grow lean very 
rapidly. I therefore agree with Barfurth that a certain degree of ema- 
ciation is, from causes regarding which we can as yet hardly venture a 
supposition, in both sexes a necessary, or at least profitable or favorable, 
condition of the complete development of the sexual organs, or of the 
act of copulation. And the different conditions of migration aim at 
reaching a comparatively normal spawning condition at the right time, 
and at the same time for all fish, no matter from what different points 
they have started in the race for life. The fat fish, therefore, as a 
general rule, immigrate earlier than the lean fish. 
’ As the causes, to which the constantly recurring typical differences 
of natural phenomena may be traced, become simpler as the statistical 
data, which show them, become numerically larger, I consider the differ- 
ent length of the fattening-period, viz, of the scjourn in the sea, as the 
simplest cause of the varying quantity of fat found in the immigrating 
salmon. 
