466 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [40] 
must be looked upon as perfectly natural, but in some groups (not till 
July, however) some individuals attract attention by their exception- 
ally small weight, whilst there is no difference of length. Such fish, 
(some of which I myself have seen) occur only in isolated instances, 
one or two being found in a group, and they differ from the next small- 
est by 500 to 1,000 grams. We evidently have here extremes not pro- 
duced by natural causes, but by some extraordinary cause. I have 
sometimes thought that these fish are possibly the counterparts of the 
winter salmon—impatient fish, which, after their return to the sea, | 
do not skip the spawning period, but which immigrate as early as the 
summer of the same year, though their quantity of substance is as yet 
incomplete. Against this, however, speaks the very small weight of 
the pectoral fins (5.26 per cent. of the body) in a November salmon 
which I examined. If, moreover, we take those fish from all groups 
which differ very considerably from the average weight, and place them 
in groups, each varying from the other by 100 grams, we find no tend- 
ency whatever in these figures to form an independent curve; they are 
and remain scattered and disconnected figures. I therefore consider it 
probable, at least for the present, that these are pathological cases— 
fish which, during an invasion of leeches (much feared in early sum- 
mer, especially when the water is low), or owing to some disease, have 
lost some of their substance. Supposing this to be the case, I have 
excluded these scattered figures from the calculation of the averages. 
Their number is very small (about 15 among 470). 
The emaciation of the Rhine salmon in fresh water, which is really 
the main point of our entire investigation, has now been viewed by us 
from two standpoints, viz, as self-consumption, in its relation to the 
length of the starving condition, and as a yielding of substance for the 
building up of the ovarium. Both these processes require albumen and 
fat; both draw albumen and fat from the muscle of the trunk, which in 
March salmon, and even in winter (December) salmon, shows distinct 
traces of fatty degeneration. But whilst the self-consumption uses 
much fat, but very little albumen, as is shown conclusively by a com- 
parison of the spring salmon with the midsummer salmon, the growing 
demand of the ovarivum for substance makes considerable inroads on 
the albumen of the muscle of the trunk in a progression which is not. 
quite regular, and has the same effect as a wasting disease, no matter 
whether there is much fat or not. Where, therefore, are we to look for 
the analogy, and where for the difference of these two processes? 
The solution of this problem is, in my opinion, found in the condition 
of the muscles of the fins and of the head, regarding which I have nu- 
merous data, showing weights and quantities of albumen; these mus- 
cles but rarely share in the fatty degeneration, and they decrease but 
little, if any, in weight and albumen. What can be the cause? That 
it cannot be a so-called ‘morphological cause” (which, to me, is an en- 
tirely vague idea, though some other people may be able to fathom it) is 
