Life-Jiistory of Sahnoii. Ill 



report is devoted, and especially to the verification of the 

 investigation ot" Professor P. Meischer liuesch *. 



As a result of his investigations on this point Dr. Noel 

 Paton finds that, as regards the muscles, the percentage of 

 solids, although throughout the season markedly higher in 

 the fish at the mouth than in the tisli in the upper reaches 

 of the river, remains unaltered in all until August. In 

 October and November it falls markedly, but the weight of 

 the muscle shows no diminution, being kept up by the addi- 

 tion of water ([». 86). The ovaries, on the contrary, increase 

 in solids ; and a bal.mce of loss of muscle and gain of ovaries 

 may b^ struck, from which it appears that " the amount of 

 so/ids lost bi/ the mu>^cle. is not only amply sufficient to yield the 

 solids (jained by the ooary^ but a large surplus is left''' (p. 87). 



Similarly in a male fish the testes increase in size at the 

 expense of the muscle, but they do not attain to anything like 

 the same propor:ionate weight of the whole tish, as do the 

 ovaries. Observations on male tish were more limited than 

 those on female ; but a balance and loss table was drawn 

 up, from which the conclusion was drawn that " the supply of 

 solids, over that required for the construction of the testes, 

 which is thus available for muscular energy ^ is considerably 

 qreuter in the case of the male than of the female fish " (pp. 8S 



Passing on to a consideration of the various substances 

 included in the term '' solid," it is found that chemical obser- 

 vations show that "the fish leaves its marine feeding-ground 

 with the muscle loaded with fat, and that this fat gradually 

 diminishes in amount, being in part transmitted to the ovary 

 and in part used up as a source of energy " (p. lOiJ). The 

 store of fat is, in fact, according to Dr. Paton, " not only 

 aiiqjly svjfficient to yield all the fat required for the fat of the 

 growing ovary, but also abundantly sufficient to yield energy 

 for an enormous amount of muscular work^^ (p. 98). 



As regards the origin of this fat, it would appear that fat 

 is drawn not only from the muscles, but from the intestines, 

 and that " this intestinal jat is the fimt to be drawn upon, and 

 that it is used up more rapidly than the muscle-fat " (p. 100). 

 Further, " the fats stored in the liver while the fsh is feeding 

 in the sea are to a great extent lost during the sojourn in fresh 

 water. As much as 20grm. of fat per tish of standard length 



* ' Statis^tiriche und biologische Beitvage zur Kenntniss von Lebendes 

 Ilheinlachses in Siisssvasiier.' A contribution to the literature of the 

 Berlin Fisheries Exhibition of 1880. Published by \'on Metzer and 

 \\'iltig, Leipsic. See also ' ilistochemischen und physiologischen Av- 

 boittu,' von Frederich Mirsciior, lid. ii. p. 110: Leipsic, 1897. 



