41 



seven or eight years. It is probable therefore that in this case 

 growth is not accurately indicated by the experimental method. 

 The growth of the Waddington specimens appears in the Avinter 

 of the first year to be deflected from the normal path, and the same 

 feature is true of the Cullercoats specimens, which may be said 

 to have suffered during the first and more distinctly in the second 

 winter. We have then to choose between explaining this as being 

 due to season or as the result of tank conditions. 



Two considerations help us to conclude that the confinement 

 is the cause of the slow growth. The first is that in the rearing 

 experiments on a large scale at Rhode Island, Professor Mead 

 and his colleagues found that the American species, which is so 

 like our o^v^i, reaches in a year a size of 5-5 to 7-3 cm., and in two 

 years 11-43 cm. It will be noted that the Cullercoats females in 

 the first year were growing just at about that rate. The other point 

 is that when maturity is attained in the case of the female a period 

 of two years must elapse between the ecdyses. The incubation 

 period is one of about eleven months. After casting and pairing 

 the female requires a year before spawning, and the ecdysis takes 

 place immediately after hatching. 



It is seldom that berried lobsters under 9 ins. are seen. They 

 appear to be from 9 to 10 ins., say 21 to 24 cm., as a rule when 

 they come to maturity. This will mark, as we have seen it to mark 

 in these and other cases, the point of inflexion of the curve of growth 

 where the change to a more horizontal phase occurs. It would be 

 possible with all this in mind to construct an ideal curve, fitting 

 into it the ecdyses shown by experiment but neglecting the instars. 

 This, it will be seen, I have ventured to do, and that there may be 

 no confusion I had better state now that the idealised scheme 

 of the growth with reference to the female is shown by the line 

 of small dots, the actual growth of the Cullercoats females by 

 broken lines, and the actual growth of the Waddington males 

 by the continuous line. Brook's series are added to the latter, 

 and indicated by dotted lines and marked " B." The upright 

 figures below refer to the years after hatching, and the sloping 

 figures to the calendar years. The results may now be sum- 

 marised (Table IX.):— 



