BULLETIN OF THE UNITED STATES FISH COMMISSION. 21 



striictiou of maiiy eggs, although in the first lot of eggs prepared, which 

 sufi'ered greatly from iron rust, and was frequently left without care, 

 sometimes for days at a time, until they were well covered with sedi- 

 ment, fully one-third were living at the end of eight weeks, when I left 

 the Wood's Uoll station. 



It does not seem jiracticable to keep the eggs of more than one lob- 

 ster in each jar, as the eggs of different individuals differ more or less 

 in specific gravity, and it is impossible to regulate the flow of water so 

 as to give them all the required motion ; but as the number is consider- 

 able in each, there is not sufficient excuse for attempting economy in 

 that direction. The number of fertilized eggs carried by lobsters during 

 the spawning season has been ascertained by careful computations in 

 several cases, and varies from about 12,000 to 24,000, the latter number 

 probably being rare. The most common number noticed during late 

 years has been from 15,000 to 18,000. 



The question of the amount of motion to which the eggs should be 

 subjected is one deserving much consideration. The females with eggs 

 contained in the aquaria at Wood's Holl remained very quiet most of 

 the time, and the swimmerets and eggs were scarcely ever observed to 

 be in motion. Confined within the narrow limits of an aquarium, with 

 a strong light entering from all sides, it was not to be expected that 

 their movements would be altogether natural. In nature, whether or 

 not their swimmerets are kept moving regularly backwards and for- 

 wards, which is probably the case to a greater or less extent, the act 

 of moving about in search of food or for change of ground must bring 

 a constant change of water. With the Clark hatching-boxes, which are 

 very successful for certain kinds of fish eggs, no good results were ob- 

 tained, although the flow of water was much greater than in the Mc- 

 Donald jars. These boxes were tried in two ways, with a downward 

 and an upward flow of water, but the eggs remained perfectly motion- 

 less, and at the end of a week were in such bad condition that they had 

 to be thrown away. 



The experiments above described merely indicate a method by which 

 lobster eggs detached from the parent may be successfully kept alive 

 for a considerable length of time with sufficient economy to commend 

 the process to future j)ractice. Had the experiments been made during 

 the hatching season, more satisfactory results would undoubtedly have 

 been reached. It is not expected that in actual practice the eggs will 

 have to be kept very long in the jars. The extensive storage basins in 

 front of the laboratory will afford accommodations for large quantities of 

 "berried" females, which can be so arranged as to permit of their being 

 readily examined from time to time and the condition of the eggs ob- 

 served. As the eggs approach the last stages of development before 

 hatching — a condition that is easily determined almost by the unaided 

 eye — they can be transferred to the hatching-jars, and the final changes 

 allowed to take i)lace under constant observation. As the hatching is 



