26() TRANSACTIONS LIVERPOOL BIOLOOLCAL SOCIETY. 



" Ladybird " in the summer of '08, and all may be 

 explained by the abnormal heating of the surface water, 

 as can be readily seen from the curves. If the 10 fath. 

 temperature be compared in those four series with the 

 bottom (20 faths. in three cases and GO faths. in the other) 

 the differences are only 001° C, 005° C, 0'28° C, and 

 0*32° C. respectively. Thus, where the difference was so 

 great as 2'42° C. between the surface and the bottom, a 

 difference of 2 14° C. existed between the surface water 

 and that at 10 faths., plainly due to the heating effects of 

 the sun. I find, therefore, no great difference between 

 surface and bottom water, always less thau half a degree 

 except on abnormal occasions, and a difference of over 

 2° C. can be produced solely by the action of the sun's 

 rays on the surface water. Such small differences can 

 scarcely be used as evidence for the inflow of colder 

 currents from without, and I imagine will exercise no 

 perceptible influence upon the vertical distribution of 

 planktonic organisms. 



Salinities in April. 



The samples of sea-water examined were taken with 

 the Ekman Water-bottle, at the same time as the 

 temperatures. The remarks made with regard to the 

 frequency of the determinations of temperature apply, 

 therefore, with equal force here, though the temperatures 

 will naturally vary and be affected by weather conditions 

 (o a greater extent than the salinity. The salinities have 

 been determined by titrations of chlorine by Mohr's 

 method, using the Knudsen apparatus and referring the 

 results to standard sea- water. The salinities, etc., were 

 then calculated by means of Knudsen's hvdrographic 

 tables. T° is t\u> tempera lure (Centigrade) of the water 

 in situ, CI % is the amount ot chlorine per 1,000 parts of 

 water, and S%o is the salinity. 



