[15] BIOLOGY OF THE RHINE SALMON. 441 
The following table, with its different horizontal lines, will give a 
still clearer view of the subject. On these lines, counting from the 
starting points of the six groups, placed perpendicularly, the figures of 
the excess of weight (in per cents) over the final weight (=100), reduced 
for the 12th October, are given in intervals proportionate to the differ- 
ences of time: 
TaBLe V.—Average change of weight of female Rhine salmon, caught beiween Basel and 
Laufenburg, from the beginning of June till the 12th of October, six divisions, each con- 
taining fish of equal length, in 3-5 groups each, 470 fish in all. ’ 
GROUPS OR 
DIVISIONS. 
| | Division I. 
108. 05 106. 88 100 
June 19. July 29. Oct. 12. 
_ ae ee Division IL 
109. 83 103. 97 104. 45 105. 80 100 
May J June 6. July 6 Aug. 4 Oct. 12 
| | | | | Division IIL 
108. 80 108. 12 105. 81 105. 67 100 
May 22. June 26. July 19. Aug. 23 Oct. 12. 
| | Division IV. 
Division V. 
Division VI. 
June 2, July 26. 
The figures show the weights of the respective average date of a 
group when the weight on October 12 was 100. 
If, supposing that the change of weight between two average dates 
took place in a straight line, we calculate approximately the average 
proportion to the final weight (October 12 =100) for a number of suit- 
ably-selected periods of time, of all the six divisions, we obtain the 
following course of changes of weight, in which the individual differ- 
ences are very well equalized; so that, in spite of the retarding influ- 
ence of later immigrants on the emaciation (as indicated in figures) of 
the earlier ones, a slight decrease in weight may be perceived from the 
very beginning, which, resembling aparabola, describes a curved line con- 
vex towards the top.* If nothing else, this form, instead of the line (at 
first concave towards the top and then straight, indicating the emacia- 
tion by hunger), points to a connection of an organ growing in geomet- 
rical progression, with the demand for subsistence. 
* The large tables of curves have not been reproduced,—EDITOR. 
