86 



Part III. — Eighteenth Annual Report 



diameter. Here and there through the ovary appear ripe eggs which 

 have not been extruded with the main mass. In May and July, in 

 three examples dissected, yolked eggs were found ; two of the ovaries 

 were white, the third red. In the crabs which have just hatched their 

 eggs the ovaries were found to be of a red colour. (Table II., p. 94, July.) 

 In August seven examples came under observation ; they, with one 

 exception, showed developing ovaries and varying quantities of sperms in 

 the spermatheca. In October and December 1899, of the nineteen 

 dissected crabs which showed by the presence of the empty egg-capsules 

 on their swimmerets that they had hatched their eggs during the 

 summer immediately preceding, many had ripe eggs. A number of 

 crabs which had hatched their eggs in the tanks at Dunbar were kept 

 there until November. One measuring 5-| inches across had an orange 

 ovary. Four which survived till December had ovaries pink or orange 

 in colour, and containing eggs measuring from , 15--27mm. in diameter. 

 On December 1st a female measuring 5^ inches across was found to 

 have a few empty egg-capsules on the base of the swimmerets. On 

 December 9th it extruded a quantity of eggs. A berried crab, 6 inches 

 across, which was got from Dunbar on December 9th, 1899, was 

 examined on its death in February. Empty egg-capsules were found at 

 the base of the endopodite of the fourth swimmeret. They were 

 to some extent concealed by the mass of the new eggs which w T as attached 

 to the limb. The actual proof supplied by the last two crabs — 

 that the female may carry eggs in two successive years — is led up to by 

 the evidence afforded by the condition of the ovaries of the crabs which 

 had lately been berried. We have, then, in the female crab, reproduc- 

 tive periods of two years at least, separated by growth (or casting) 

 intervals. Those crabs which are not preparing to carry another batch 

 of eggs appear to cast very soon after the brood hatches ; but it is not 

 improbable that some do not cast till the following summer. A certain 

 amount of evidence bearing upon this question in the lobster has been 

 published. Herrick* writes as follows: — "Females usually moult 

 shortly after the hatching of a brood." Of several lobsters which had 

 hatched their eggs, and which were placed in confinement by Cunning- 

 ham t in September, two cast their shells — one on November 27th and 

 the other about February 9th. MeekJ records a female lobster which 

 was brought to Cullercoats Laboratory, " evidently after hatching ; 

 she cast her shell in the tank during 17-1 8th August." 



With regard to the frequency of spawning in the lobster, there has 

 been considerable divergence of opinion. Thus, Ehrenbaum§ was of 

 the opinion that the European lobster becomes productive only once in 

 four years. Fullarton || considered that the lobster did not spawn two 

 years in succession. Herrick % accepts the position of Garman, viz., 

 " that the female lobster lays eggs but once in two years, the laying 

 periods being two years apart." Herrick found immature ovaries in 21 

 lobsters which had recently hatched their eggs, and concludes — " That 

 the spawning periods are thus two years apart is a valid inference drawn 

 from the study of the reproductive organs" (p. 71). Allen** in this 

 connection says — " An examination made at the end of July of the ovary 



* Op. cit., p. 35. 

 t Op. cit, pp. 40, 41. 



J Northumberland Sea Fisheries Committee. "Report on the Trawling Excursions, 

 &c," 1899, p. 54. 



§" Der Helgolander Hummer," Wissenschaftliche Mecresvntersuchungen, Neue Folge, 1 

 Bd.. Hft. 1, Kiel, 1894. 

 || Fourteenth Annual Report of the Fishery Board, Part III., p. 186. 

 IT Op. cit, p. 70. 



** "The Reproduction of the Lobster," Journal of the Marine Biological Association, 

 N. S., Vol IV., No 1, pp. 60-69. 



