HABITS AND DEVELOPMENT OF THE LOBSTER. 79 



Over 100 dissections were made in the summer of 1890 (June 28 to August 19) to 

 determine the period at which female lobsters mature, and to follow out the devel- 

 opment of the reproductive organs; out of this number, 25 lobsters, from 9.31 to 12 

 inches in length, had never spawned; 5 of these were between 10 and 11 inches long, 

 and G between 11 and 12 inches. In many cases it was demonstrable that the 

 ovaries of these lobsters could not have become mature in less than two years. It is 

 therefore obvious that the lengths of 9, 10, and 10i inches, which have been adopted 

 in different States as standards below which no lobsters are allowed to be sold, should 

 be raised, if these animals are to receive the fullest benefit from this kind of legisla- 

 tion. 



The eggs of the greater number are laid at a definite period and are attached by a 

 gluey secretion, coming from cement glands* in the legs of the "tail,' 1 to the long 

 hairs which garnish these appendages and to the under side of the "tail" itself. They 

 are thus carried about by the female, and protected for a period of from ten to eleven 

 months, when they hatch, and the young which then leave the mother lead an iude 

 pendent, free-swimming life, near the surface of the water. 



The number of eggs laid varies with the size of the animal producing them, from 

 3,000 to 9,000, in the case of a female 8 inches long, to 85,000 in one measuring 16i 

 inches. This is the largest egg-bearing female of which I have any record. Lobsters 

 10i inches long, from Vineyard Sound, produce, on the average, 11,000 eggs. 



The law of production may be stated as follows : The numbers of eggs produced 

 by female lobsters vary in a geometrical series, while the lengths of the lobsters producing 



* The cement glands, which are responsible for the viscous secretion in which the eggs are bathed 

 at the time they are laid, and by means of which they are afterwards tirmly secured to the body, are 

 of microscopical size and occur in very great numbers. Thej are most numerous on the hinder faces 

 of the second to fifth pair of swimmerets of the female. Each consists of a spherical cluster of 

 upwards of a hundred large glandular cells, which terminate in a central rosette (a peculiar, reticulate 

 structure whose nature I have not determined). In the center of this rosette a small lumen or empty 

 cavity is usually seen. The lumen communicates with the exterior by a very delicate chitinous tube, 

 the duct of the gland. This thread-like duct penetrates the chitinous covering of the swimmeret 

 and opens at the surface by a minute pore. Each gland has a large, nearly central, ganglion- cell, 

 which is connected with the rosette and with the nerve which supplies the gland. Organs of very 

 similar structure occur in great numbers in the appendages about the mouth, particularly in the man- 

 dibles, maxilbe, the upper and lower lips (labrum and metastoma), and seem, from physiological 

 experiments, to be sense organs, probably of a gustatory nature. These two kinds of oigans, cement- 

 gland and appendicular sense-organ, while agreeing in general structure, give an entirely different 

 micro-chemical reaction. This analysis shows that the organs of the swimming-feet are undoubtedly 

 glandular in their nature, and we must infer either that both kinds of organs are really glands, or 

 that there is a close relation between glands and sense-organs of this particular type. 



The cement glands, like the mammary glands of some mammals, are capable of active secretion 

 only at definite reproductive periods, namely, at the time of egg-laying in the case of the lobster. The 

 liquid secretion is probably poured out very slowly, and trickles down the sides of the swimmerets upon 

 their hairs and into the pouch or cavity formed by the folding of the " tail," where we know, by obser- 

 vations made on other Crustacea, that the eggs are stirred up by the movements of the swimmerets until 

 they become effectually " varnished " and fixed in place by the cement substance. This is not viscous 

 at first, and it is probably some hours before it becomes very tenacious. An interestingcase of alobster 

 which had laid her eggs in the well of a fishing smack came to my notice this summer at Rockland, Me. 

 The lobster was taken out of the well and laid on deck, when the newly laid eggs began to flow out from 

 under the " tail." The crayfish has often been found with the eggs in a similar condition. After a longer 

 contact with sea water the liquid cement becomes, as is well known, very tough and inelastic, resembling 

 chitin in its general appearance and properties. 



