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SUMMARY OF ci'Klil'.NT RESEARCHES RELATING TO 



devised for keeping copper-oxide-ammonia solution from the action of 

 air. This reagent, so important in testing the fibres of hemp and flax, 

 rapidly deteriorates, and under ordinary conditions is not permanent for 

 long. The bottle is made of brown glass, and, as will be seen in the 

 illustration (fig. 23), the neck is closed by a caoutchouc plug, in which 

 are two holes for the passage of glass tubes ; one of these dips into the 

 ammoniated copper solution, the other just ends below the stopper, its 

 outer extremity being fitted with a teat having a small perforation. The 



copper solution is covered with a layer of paraffin oil. The same device 

 is used for several purposes in laboratories, but has not been exploited 

 for this special purpose before. 



Simple Arrangement for Determining the Sinking-velocity of 

 Plankton Organisms.*— F. Krause was led to contrive his apparatus 

 by desire of pursuing the following investigations : " What influence 

 has body-form and body-magnitude of plankton-organisms on their 

 sinking-velocity ? How is the velocity of the same individual affected 

 by the viscosity of the medium ? How are such results affected by 

 various temperatures in the same water ? " His apparatus consists of 

 two parts — a receptacle for the organism, and an observation instru- 

 ment. The receptacle is formed out of a rectangular metal plate 

 65 mm. long, 85 mm. broad, and 2 5 mm. thick, whose middle part is 

 cut away so as to leave a rectangular notch 45 mm. long and 6 mm. 



* Zeitschr. wiss. Mikrosk., xxvii. (1910) pp. 347-9 (2 figs.). 



