[23] BIOLOGY OF THE RHINE SALMON. 449 
TABLE X.—Proportion of weight of the muscles of the pectoral fin (of one side) to the 
weight of body of female summer salmon and spawning salmon. 
’ : | 1,000 parts contain pec- 
Weight of body— Weight of |  toral fin calculated on 
muscles weight of body— 
of the 7 mE 
, : pectoral 
With Without fin. With Withont 
ovarium. | ovarium. ovarium. | ovarium. 
DUTCH FISH. 
May. 31, 1879; ovariaum.31,.......-........ 6, 800 6, 760 19.1 2, 808 | 2, 825 
SALMON CAUGHT BETWEEN BASLE AND 
LAUFENBURG. 
July 1, 1879, ovarium 198 ................ 9, 750 9, 550 34. 23 3, SLL 3, 584 
July 2, 1879, ovariura 300 ................ 9, 700 9, 400 32. 41 3, 341 3, 448 
July 9, 1879, ovarium 291 .............-.- 8, 560 8, 270 30. 45 3, 557 3, 682 
July 21, 1879, ovarium 341 ............... 10, 270 9, 930 | 35. 30 | 3, 437 3, 555 
duly 28; 1879, ovarium 394 .......:....... 7,440 7, 050 26.14 3, 513 3, 708 
August 1, 1879, ovarium 802 ............. 11, 130 10, 330 32. 72 2,940 3, 167 
August 4, 1879, ovarium 429 ............. | 7, 340 6, 910 25.10 3, 420 3, 632 
August 7, 1879, ovarium 279.5..........-.. | &, 980 8, 650 | 30. 03 3, 363 3, 472 
August 25, 1879, ovarium 505 ............ 7, 745 7, 249 26. 69 3, 446 3, 686 
Averavosser eats. 5.24003 Orisa Depa eey mice? | cal @eegeea ed eeeeararnaes 3, 392 3, 548 
November 3, 1879, ovarium 20.40......... | ol 740 5, 700 25. 99 3, 358 4, 560 
November 4,°1879, ovarium 18.18......... | 9, 620 7, 800 34. 30 | 3, 565 4, 397 
November 8, 1879, ovarium 20.44. ........ &, 900 7,190 34. 02 | 3, 822 4, 732 
November 10, 1879, ovarium 20.44......- | 7, 650 | 5, 610 | 24. 85 | 38, 248 4,429 
November 15, 1979, ovarium 16.10........ | 6, 750 5, 180 | 24.71 3, 661 4, 817 
November 22, 1879, ovarium 85........- | 7,510 | 7, 420 Sat | saceter cee. | 4, 462 
November 22; 1879) 117°5. 22-0. 0...002- | 7, 290 | 7,170 | Doe eea| weer a cme aaa 4, 494 
INOVOMDOT: 20 ye sec eccc as waceciae othaedere = | DT30V emereet aes JS1O6 Neeeeneeae 4, 967 
RV ORALO oes e2 pce bctecs deat esee | eo ee een ae eset, Sek | 3, 531 | 4, 607 
| | 
It will be seen from Table X that the muscles of the pectoral fin main- 
tain the same proportion to the weight of the body from summer till 
November, or even—corresponding to the decrease of weight of the 
fish—increase somewhat, thus furnishing proof that the ovarium takes 
the place of muscle-substance which has been used up. 
The decrease of albumen in the fin-muscles is either very small or 
there is no decrease at all. The very muscles, therefore, which are most 
necessary to the fish for its motions, remain singularly free from ema- 
ciation, and are even built up at the expense of substances furnished by 
the muscle of the body. On the other hand, the fact that the-fins re- 
main the same—in spite of the increase of the ovarium—furnishes an- 
other convincing proof that the ovarium cannot be considered merely 
as an addition to the existing body, but is really a substitute for sub- 
stance (belonging to the body) which has been lost. 
All the above facts prove, with absolute certainty, that (with very few 
exceptions) all the Rhine salmon caught between Basel and Laufenburg go 
through their entire sexual development, and the entire growth of the ova- 
rium, at the expense of the body, whilst in the Rhine. 
As regards the male fish I have not such full and accurate calcula- 
tions. The few given below will show, however, beyond a doubt, that 
from midsummer to October there is a very noticeable decrease of 
weight. 
S. Mis. 29-———29 
