428 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 
In the female the difference is less apparent. There is not much dif- 
ference in the length and shape of the nose; the red spots on the body 
and head, which are entirely wanting in the “ winter salmon,” are not 
as strongly developed in the female as in the male salmon; the skin is 
~ dark and looks as if it was covered with impurities, but is not as thick. 
The principal difference in the outward appearance is caused by the 
different development of the ovaria, which in the winter salmon weigh 4 
per cent., and in the spawning salmon fully one-fourth of the total weight 
of the body, so that they bloat the belly very considerably, making the 
back appear particularly thin. As soon as the eggs have been emptied” 
out, the thin, limber walls of the abdomen make the leanness still more 
apparent. 
it is well known that there is a considerable difference in the quality 
of the flesh, which in the winter salmon is peculiarly red (caused by 
coloring matter, which is soluble in alcohol and ether, but not in water, 
and which—partly at least—is inherent in the muscle-fibers) and inter- 
larded with strips of fat; im the spawning salmon it is of a dirty white 
color. After the spawning season it becomes more transparent. The 
intestinal canal of the winter salmon is covered with fat; the append- 
ages of the duodenum are actually enveloped in layers of fat, whilst in 
the spawning salmon it looks as if all the fat had been peeled off and 
at the same time the intestinal canal itself thinned, so that in the former 
the entire weight is about 24 per cent. and in the latter one-half to three- 
fourths per cezt. of the total weight of the body. 
Although it cannot have escaped an attentive observer that between 
these two extremes (the winter salmon and the spawning salmon) there 
are different intermediate varieties, the mutual relations of all these 
fish have not yet been perfectly cleared up. Although it was known 
long since that those salmon which immigrate from the sea do not reach 
their full maturity till they have reached the Rhine, some people think 
that their stay in the fresh water is confined to a few months. The cir- 
cumstance that in November and December there are caught, besides 
the mature fish, a few very fat fish, with very small and hardiy devel- 
oped sexual organs, has led people to suppose that besides those sal- 
mon which ascend the Rhine for the purpose of spawning, there are 
also found, temporarily or permanently, barren fish, which for some very 
Strange reason occasionally stay in the Rhine, and which, when caught, 
of course, do not thereby interfere with the propagation of the species. 
This opinion seemed to be further corroborated when Barfurth* brought 
to the attention of science a view which had long since been entertained 
by practical men, such as Mr, Glaser, and which had also been made 
known to the scientific world by His,t viz, that the Rhine salmon, during 
its stay in fresh water, does not take any food. Barfurth has reached this 
*TROSCHEL’S Archiv fiir Naturgeschichte, vol. xli, i, 122, 1875. 
tHais: Untersuchungen iiber das Ki und die Lientwickelung bei Knochenjischen. Leipzig, 
1873, p. 24. 
