THE AMERICAN LOBSTER. 35 



THE PAIRING OF THE LOBSTER AND OF OTHER CRUSTACEA. 



The copulation of the lobster has never been seen, as far as r am aware, in any of 

 the species, but we know that it takes place- in spring and summer at least, it' not at 

 other times of the year*. If ripe females, or females even Avith newly laid eggs, are 

 examined in June or July at Woods Hole, the seminal receptacle is found to be almost, 

 invariably charged with spermatozoa, and it is evident that copulation takes place, 

 certainly in many cases, without immediate reference to the condition of the animal. 

 Thus on August 19 T examined a female lobster which was 9 inches long and found 

 her seminal receptacle loaded with sperm. The ovaries were of a light, greenish -yellow 

 color, and in a very immature condition. This lobster had been impregnated at least 

 two years before her eggs would be ripe. 



I was surprised to find the seminal pouch of another lobster, which was examined 

 about the same time, to be charged with freshly deposited sperm, althoughit had just 

 hatched a, brood and was preparing to molt. It therefore seems probable that the 

 male lobster has no means of discriminating the sexual condition of the female. This 

 lobster, in the ordinary course of nature, would soon have lost in the molt the sperm 

 with which she had been so recently supplied. The first copulation, which had occurred 

 either before or shortly after the hatching of the brood, must have been followed by a 

 second union in order to secure the fertilization of the next batch of eggs. These 

 would not be due, moreover, until one year from this time. It is thus evident that 

 the female lobster is not impregnated once for all and compelled to take the chances 

 of fertilizing her eggs, but is approached more than once by the male. The molting 

 of these animals, although subject to less variation in the adult female than in the 

 male, renders this necessary. Females usually molt shortly after the hatching of a 

 brood. Where the molting is accomplished just before the eggs are laid, which 

 happens very rarely — I have noticed only two cases in the lobster — (see p. 80), copu- 

 lation can precede the act of extrusion by a few days at the most. 



A lobster which had been kept in an aquarium for upward of two months in the 

 summer, without access to the male, laid eggs which were normally fertilized. This 

 and other facts which have just been mentioned show that the female lobster must in 

 some cases be impregnated more than once before each reproductive period, and also 

 that the spermatozoa retain their vital activities for a long time, perhaps, as Bumpus 

 suggests (30), from one to two years. This is not so remarkable, when w , onsider 

 the longevity of spermatozoa recorded by Sir John Lubbock (Weismann's Essays, 

 vol. 1, p. 52), who succeeded in keeping a queen ant until she was 15 years old, 

 during which time she continued to lay fertile eggs. Fertilization must have taken 

 place at the latest in the season when the insect was captured. "There has been no 

 male iu the nest since then," writes Lubbock, "and, moreover, it is, I believe, well 

 established that queen ants and queen bees are fertilized once for all. Hence, the 

 spermatozoa of 1874 must have retained their life and energy for thirteen years, a 

 fact, I believe, unparalleled in physiology." 



Observations on the copulation of the crayfish (Potamobius fluviatilis) have been 

 made by Gerbe (43), Chantran, and other naturalists. The latest and most detailed 

 account of Chantran, published in 1872 (.5.9), is as follows: 1 



1 In quotations from works in foreign languages, I shall give, for convenience, the English trans- 

 lation. The extract can he verified by reference to the original. 



