70 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



is always of an opaque grayish-white tint (plate 38, fig. 136). The ovary of a lobster 

 taken at the time of the hatching of the brood (plate 38, fig. 138), or several weeks 

 after it, is invariably, so far as my observation goes, of a light pea-green color, and 

 possesses definite histological characteristics which will be considered in another place. 



The ovary of a female which is approaching maturity for the first time (see Nos. 22, 

 26, 47, 58, 67, 74, 83, etc., table 20), on the other hand, is variable in color. It may have 

 a flesh or almost salmon tint, a cream color, a dirty yellow, bright light-yellow, light 

 olive-green color, or one of many intermediate tints. 



The interesting fact has already been pointed out that the percentage variation in 

 the numbers of eggs produced by lobsters from 8 to 12 inches is excessively great. 

 This points to the conclusion, which is confirmed by anatomical evidence, that the 

 period at which lobsters reach sexual maturity is a variable one, extending over 

 several years, over a period, at least, in which lobsters vary from 8 inches, or slightly 

 under, to 12 inches, or slightly over, in length. 



THE FREQUENCY OF SPAWNING. 



Is the lobster an aiinual spawner, or, to put the question in another way, what 

 percentage of mature female lobsters produce external eggs each year"? These ques- 

 tions, although of much importance, have generally received erroneous answers. 



In the summer of 1890 I first demonstrated, upon the ground of anatomy, that the 

 lobster did not and could not breed annually, as had been commonly supposed. This 

 is proved, first, by the growth of the ovarian eggs, and confirmed by the relatively small 

 percentage of females with external eggs captured during the winter and spring. 



The growth of the ovarian eggs was followed from the time of hatching of the 

 brood until the ova of the next generation were ripe and ready for extrusion. (See 

 note, p. 152.) These results are embodied in table 20. In some notes published 

 in May, 1891, 1 pointed out that three-fourths of the whole number of egg-lobsters exam- 

 ined in the summer of 1890 in Vineyard Sound had extruded eggs during the latter 

 part of July (see table 7). It was also shown that the eggs which are then laid are 

 "carried by the female throughout the fall, winter, and spring, and are not hatched 

 under natural conditions until the following summer" {92). The hatching period 

 was given as extending over a period of about eight weeks, from May 15 to July 15. 

 This agrees, for the most part, with the experience of recent years. 



Bumpus (30) gives correctly the periods of spawning — with the exceptions I have 

 noted— of incubation, and hatching of the young. Garman (72), in a report upon the 

 lobster to the fishery commissioner of Massachusetts, summarizes his results as follows : 



(1) The female lobster lays eggs but once in two years, the laying periods being two years apart. 



(2) The normal time of laying is when the water has reached its summer temperature, varying in 

 different seasons and places, the period extending from about the middle of June till about the 1st of 

 September. 



(3) The eggs do not hatch before the summer following that in which they were laid, the time 

 of hatching varying with the temperature, and the period extending from the middle of May till 

 about the 1st of August. 



These conclusions— subject to the corrections which I have pointed out— are essen- 

 tially a repetition and confirmation of facts which were already known. 



Mather emphasizes (135,136) the facts that the lobster carries its summer eggs all 

 winter and that it breeds once in two years. 



In order to prove with certainty that the lobster can not breed every year, we 

 have only to dissect a female which has recently produced a brood, or has external 

 eggs nearly ready to hatch, in June, July, or August. In table 20 records of over 



