BIOLOGICAL EXAMINATION OF DISTILLED WATER. 



I 99 



in column 2 were added. To the dishes were added equal 

 amounts of Arbacia eggs in 16 32-cell stage. 



Experiment n. Two liters of sea-water were evaporated to 

 250 c.c. To 10 c.c. portions of the resulting solution were 

 added respectively 70 c.c. of waters described below. Equal 

 quantities of Arbacia eggs were added. Three days later the per- 

 centages of plutei were ascertained by first killing the cultures and 

 then making counts in a watch glass marked off into squares. 



Per cent. 

 Plutei. 



I. 



Control, 80 c.c. sea-water. 



2. Artificial sea-water made from tap-water. 



3. " " " " " tap-water heated to 60 in closed flask. 

 " " " " " distilled water from Metcalf's, Boston. 

 " " " " " water boiled in copper without H 2 SO 4 



but condensed in glass. 

 6. Artificial sea-water made from water boiled in copper with H 2 SO 4 but 



condensed in glass. 

 Artificial sea-water made from water distilled wholly in glass ; first 



part thrown away. 

 Artificial sea-water made from water distilled in patent automatic 



metal still. 

 Artificial sea-water made from water distilled wholly in glass, with 



K 2 Cr 2 O 7 and H 2 SO 4 . 



10. Artificial sea-water made from water double distilled in glass, first 



distillates rejected. 



11. Artificial sea-water made from " Pureoxia " distilled water. 



4- 

 5- 



7- 

 8. 



9- 



90 



o 



o 

 161 



32 , 



78* 

 66 



5 3 

 87 



90 

 3 4 



Experiment 8.-- Two liters of sea-water were boiled down to 

 400 c.c. Ten c.c. of this concentrated sea-water were added to 

 40 c.c. of each of the waters listed in column 2. To every dish was 

 added an equal amount of fertilized Arbacia eggs on July 10, 1903- 



1 Nearly all small. 



2 Some small ; others as good as control. 



3 All very small and imperfect. 



4 All very small and imperfect. Only experiment with this brand. 



