62 THE REPRODUCTION OF THE LORSTER. 



fellows. In cases where the ova are mature, but are not shed, a curious 

 physiological process is set up, the yolk of the unlaid eggs being 

 re-absorbed, and passing into the blood. The blood, in this way, becomes 

 dark green, or almost black, and the dark colour is visible through the 

 thin membranes, especially on the under side of the abdomen. Such 

 animals are known as " black " lobsters, and, if the process has been 

 allowed to proceed far, they are unsaleable. The first appearances of 

 this blackening are, therefore, carefully watched for by the owners of 

 the cages, in order tliat the animals may be sold before they become 

 valueless. " Black " lobsters begin to appear about the end of July. 

 Ehreubaum states also, that, in individual cases, lobsters in the cages 

 have spawned, the dates given being 20th, 23rd, and 26th July, the first 

 days of August, and the 28th August. He is also able in two cases to 

 give direct information as to the time the female lobsters carry their 

 eggs. In the first case, eggs spawned during the early days of August, 

 1892, commenced to hatch on the 20th July, 1893. In the second case, 

 the eggs were laid on the 28th August, 1893, and the majority of the 

 larvae hatched on the 21st July, 1894. This would give about eleven 

 months as the period of incubation. It should be noted, however, that 

 the lobsters must have been kept in a state of confinement during the 

 time that the eggs were developing.* 



My own observations on our English lobster (Homarus vulgaris), 

 although not made systematically for the purpose of determining these 

 points, but, rather, from the necessity of examining numerous egg- 

 bearing females at different times of the year, in connection with other 

 investigations, agree with those of Ehrenbaum in pointing to the 

 conclusion that, on the whole, the history of the reproduction of this 

 species is similar to that of the American representative of the 



genus. 



Females with newly-laid eggs were first obtained during the latter 

 half of July, but out of a large number of lobsters examined, only two 

 specimens in this condition were found. During August and Sep- 

 tember my work on the subject was interrupted, but on taking it up 

 again in October (1893), females carrying eggs were plentiful, but all 

 the eggs were either in the nauplius stage, with no eye-pigment yet 

 deposited, or in stages in which eye-pigment was just commencing to be 

 seen. These facts, namely, that newly-laid eggs were scarce during the 



* In the sixth Annual J'rport of the Fishery Board for Scotland, p. 196, Prof. Ewart and 

 Dr. Fulton state that in Rothesay Aquarium, a female, with ova, beini; placed in the tanks 

 in August, 1886, hatching was only comjileted in August, 1887, some of the young lobsters 

 being hatched as early as April. It seems fairly certain from this result, that confinement 

 tends to produce an abnormal rate of development, as, in the case of lobsters captured when 

 the eggs are nearly ready to hatch and placed in the tanks of the Plymouth Laborator)', 

 hatching is usually completed within a week, at most, from the time it commences. 



