REPORT OF COMMISSIONERS OF INLAND FISHERIES. 75 



The main problem, and, at the same time, the chief difficult}', in 

 the artificial propagation of lobsters consists in rearing the newly 

 hatched, free-swimming fry through the critical period of about two 

 or three weeks. This is a definite period which is passed as soon as 

 the fry shed their skins three times. At each moult the young lob- 

 ster appears in a different form and of a larger size, and there is no 

 difficulty in recognizing the successive stages. It is the critical 

 period for the reason that, until the eggs are hatched, they are well 

 protected by the mother, and after this period has expired the fry 

 assume almost the likeness of the adult form, and in great measure 

 quit their precarious swimming life, and begin, for the first time, 

 to burrow and crawl, hide and fight, at the bottom of the sea. 



The difficulty in rearing fry through this period in any consider- 

 able numbers consists in so confining them that they will not die 

 from the effects of suffocation, mechanical shock, starvation, can- 

 nibalism, or parasites. A large number of experiments were tried 

 by ourselves, as well as by others, before we hit upon the principle 

 iipon which we have based our operations during the last three years. 

 The principle is simply this: the water must be stirred constantly, 

 and the lobsters and their food kept suspended in the water. 



The first apparatus built on this principle was installed in 1901, 

 and was highly successful. In 1902 a number of important changes 

 were made in the construction of the apparatus, and nearly all of 

 them turned out to be improvements. Few alterations were made 

 during the past season, but some were suggested by the experiments 

 that will, it is hoped, in the future, improve the efficiency of the ap- 

 paratus. For a detailed description of this apparatus and the re- 

 sults obtained up to the past season, we must refer the reader to the 

 last report. 



During the season just past all the fry which were used were 

 hatched at our own station with this same apparatus, while hereto- 

 fore we have depended in part on importations from the United 

 States Fish Commission at Woods Holl. The hatching was car- 

 ried on successfully and on a larger scale than ever before. Several 



