474 MAX MORSE 



when the individuals were allowed to mingle and through their 

 disintegration the water fouled and the specimens suffered. 



Conditions at New Haven were quite different, which is a val- 

 uable check to the Maine experiments. Here the worms live in 

 sea-water which has a large fresh- water dilution. Moreover, 

 the sewage from the city must exert a decided influence in altering 

 the character of the sea-water. 



Finally, at Woods Hole, there was an unfortunate dearth of 

 favorable material of Arbacia, during the season of 1911, which 

 did not permit of as extended a series of observations as otherwise. 

 Only eggs where the check gave decidedly favorable results were 

 used and at times it was found difficult to procure many individ- 

 uals answering this requirement. 



Environmental conditions 



Certain determinations of environmental conditions were made 

 which may be of some value in regard to the experiments conducted 

 upon the same material (Cerebratulus) but at different times and 

 places. I shall present these data in table on page 475. ■ 



It will be seen that the water at Woods Hole and at New Haven 

 run similarly, while the Harpswell water has a higher acid content 

 (or lower OH content). Whether this difference is due to the 

 sewage in these cases, I cannot determine, but I should be inclined 

 to assume that this is not the case, at least at Woods Hole, for 

 the water from Vineyard Sound is comparatively clean, judging 

 from determinations of nitrates and nitrites and other factors 

 determined by the United States Bureau of Fisheries survey of 

 1904-09. It is probably a matter of normal constituents. The 

 water at Harpswell comes partly from the cold Arctic Current^ 

 which bathes the Gulf of Maine, while the Long Island and Vine- 

 yard Sound water comes largely from the Gulf Stream. 



Such are some of the environmental conditions which may have 

 some bearing upon the following experiments with Cerebratulus. 



2 Oceanographers are abandoning the idea of a current of this nature and 

 explain the cold water of the Gulf of Maine as coming from cold depths. 



