436 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 
From what has been said, it must be supposed that the early, and very 
immature, immigrants complete their entire sexual development in the 
Rhine. For the present, however, my assertion that this also applies 
as a rule to the later immigrants, lacks proof. ‘There, is however, still a 
possibility that, besides these, more mature fish immigrate from the sea. 
THE LOSS OF MATTER SUSTAINED BY THE BODY. 
In order to decide with absolute certainty whether this course of 
development in fresh water, applies to the Rhine salmon from Basel to 
Laufenburg, not only in many cases, but in all cases, we followed another 
course. 
The building-up of the mature ovarium of the winter salmon from very 
insignificant beginnings, is—viewed merely as a material process—a 
most astonishing performance. The weight amounts to from 19 to 27 per 
cent. of the total weight of the body, with 40 to 43 per cent. dry substance 
(at 110°), of which, taking the average of two fish, not quite one-fourth 
(equal to) about 9 per cent. of the fresh ovarium is oily fat. As at this 
period the muscle substance of the body contains only about 20 per cent.,, 
and often even less, dry substance, and as the fat of the intestines and 
the skin has nearly vanished, the assertion that fully one-third of all the 
jirm substance of the body is, during the spawning season, found in the ova- 
rium makes the proportion too low rather than too high. 
If the entire development of the ovarium, in fresh water, is going on 
while the fish is fasting, the body of the average spawning salmon, 
compared with the body of the average spring or summer salmon, must 
show a decrease of the matter in the other organs, at least sufficient for 
building the entire ovarium, and even (on account of the self-consump- 
tion) more than sufficient for that purpose. As during the few months,. 
from the end of July to the beginning of November, when the ovarium 
increases from 4 to 25 per cent. of the total weight of the body, the ver- 
tebral column of the fasting fish will hardly grow much in length, and 
as there are no indications (hyperdermic) to be seen in cuts, with the 
naked eye, all that should be done would be to examine fish of equal 
length at different seasons. 
Those -salmon, however, which bring a three-fourths or entirely ma- 
ture ovarium from the sea, produced by the ample and rich food found 
there, must, even if the muscle-flesh were somewhat leaner and reduced 
in weight, show a larger weight and a greater amount of substance (in- 
cluding the ovarium) than the spring and summer salmon of equal 
length and equal ovarium. | 
There would, moreover, be noticed a very decided difference between 
such spawning-salmon and those which (according to what has been 
said above) undoubtedly supply the substance for the entire ovalium 
from their own body. But this is certainly not the case. There are not 
two categories of Spawning-salmon. Whenever a spawning-salmon is, 
exceptionally, somewhat stouter when compared with its length than 
