456 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



The waters of Kew York Ilarbor were foiiud to have less than half 

 the normal average specific gravity of those of the open sea, a diliiculty 

 ■which was overcome in some measure by the use of artificial sea water 

 of a si)ecific gravity of 1.024°. Ova fertilized in the artificial sea water 

 not only develoi)etl as well as could be expected under the other condi- 

 tions in which they were i)laced, but were also shipped from New York 

 to Washington sealed up in one-quart glass jars, packed in cracked ice, 

 and also ui>on trays covered with dampened cloths. The former method 

 of transportation, however, seemed to give the best results. 



Almost all of the observations on the embryo codfish here recorded 

 were made at Wood's HoU in January, 1881, and relate mainly to what 

 could be observed of the development of the living eggs, without further 

 preparation, under the microscope, the small dimensions of the ova and 

 hatched embryos being at the time a great bar to the jnore thorough 

 investigation which 1 have since made with other forms with somewhat 

 larger ova. What has been learned by means of sections in other types 

 has been used only in so far as was evidently apjilicable on general ])rin- 

 ciples. Taken as a whole, these studies must be regarded as dealing 

 with the eggs and embryos of Gadiis morrhua as living transparent ob- 

 jects, and not as a final monography, such as would be possible had series 

 of sections and other preparations been employed in addition. The out- 

 lines of the figures 1 believe to be approximately correct, all of them hav- 

 ing been drawn with care 'with the aid of the camera lucida. The work 

 of Sars on the same species was unfortunately not illustrated, aild is 

 therefore not as valuable as it might have been. If it had been accom- 

 panied by figures, I should probably hesitate to publish several of the 

 accompanying sketches, because the deft pencil of the Norwegian nat- 

 uralist would have i)ortrayed with much greater skill most of the stages 

 here discussed. Mr. Earll's valuable contribution* to our knowledge 

 of this fish, its habits, and its development, cannot be i)assed over in 

 silence, as a j^ood many new facts are brought to light not elsewhere 

 recorded. Unfortunately, the observations here placed upon record re- 

 late only to a period of about thirty days in all. The later changes be- 

 yond the oldest stage here discussed would without doubt be of as much 

 inten^st and importance to fish culturists as the earlier ones. 



The observations recorded throughout the text relating to other forms, 

 not here figured, will, I believe, prove of interest to those engaged in 

 similar studies. These embryological observations have been made at 

 various times and places during the last three years, and embrace as 

 subjects a considerable number of genera belonging to widely separated 

 families. Some of them have been already published, but I have not 

 felt prepared to j)ut the facts accumulated into a connected form, as a 



* A report on the history and present condition of the shore cod-fisheries of Cape 

 Ann, Miissachnsetts, together with notes on the natural history and iirtilitial propa. 

 gati«»n of the species. 13y R. E. Earll. Report of the U. S. Commissioner of Fisheries 

 for 1H78, pp. G8'l-740. 



