432 



Mr. G. Smith. 



takes place in the intermediate periods when growth is in abeyance and the 

 reproductive organs are maturing. 



In Carcinus mcenas it was shown in a previous paper that the male and 

 female differed in respect to their fat-metabolism (6). Thus in the female, 

 maturing its ovaries, it was shown that the blood became flooded with lutein 

 and fatty material to a much greater extent than the male, whose blood instead 

 of becoming yellow with lutein is charged with the pink colouring matter 

 tetronerythrin, but is not so lieavily charged with fatty material as in the case 

 of the female. Coincidently with this it was pointed out that the female does 

 not grow to the same size as the male, and this is again probably due to the 

 fact that the preponderant fat-metabolism of the female for the nourishment 

 of the eggs exerts a check on growth. Finally it has been clearly shown 

 that individuals of Carcinus infected with the parasite Sacculina do no^ 

 increase in size at all after once the parasite has established its system of 

 roots in the body of the crab, and this must certainly be ascribed to the fact 

 that the Sacculina induces a most pronounced fatty habit in the liver of the 

 crab, while the glycogenic function is permanently depressed. This has been 

 completely proved by a series of quantitative estimations and histological 

 examinations of the livers of infected crabs. The condition of the sacculinised 

 crabs, both physiological and morphological, is converted by the action of the 

 parasite into that of mature females in the act of ripening their ovaries, and 

 this, as we have seen, consists in a pronounced fatty habit and the inhibition 

 of growth. 



The above considerations on the processes occurring in normal crabs and 

 in those infected with Sacculina enable us to perceive that there is a marked 

 agreement between these processes in the higher Crustacea and the conditions 

 observed in the Cladocera. In both cases active growth (in which partheno- 

 genetic reproduction is included) is accompanied by storage and use of 

 glycogen for building up the new tissues and skin, while inhibition of growth 

 and sexual reproduction .is accompanied by storage and use of fat for the 

 nourishment of the sexual products. This storage and use of fat is more 

 pronounced in the case of the female than of the male, and it is clear that 

 the fat-metabolism in the two sexes proceeds along different lines. In the 

 case of the female the fatty material developed and stored in the metabolic 

 organs is merely transferred across to the ovary, while in the case of the 

 male it appears that the fat storage is less pronounced and that the fat is not 

 transferred as such to the testis in anything like the same quantity, but is 

 broken down and used for other purposes. 



By thus bringing the processes of growth and reproduction in the 

 Cladocera and in the higher Crustacea into agreement we obtain a certain 



