ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



587 



a considerable surface, as the alga grows but little beyond the inocula- 

 tion site. The tubes should be covered with rubber caps to prevent 

 evaporation. Cultures of Chlorella obtained by the foregoing method 

 enabled the author to rear Infusoria and Cladocera. 



Scotia. Closing Plankton Net.* — W. S. Bruce describes a form of 

 closing net (fig. 94) constructed after a design the idea of which was 



Fig. 94. 



derived from the Scottish reversing thermometer frame. A weight runs 

 down the cord A, strikes.the lever B, raises brass rod C, which liberates 

 hook D from position X to Y. This lets go net-cords E, and the net 

 becomes suspended as in position Y by cord F, which has a continuation 

 of A and draws up neck of net and closes it. F is passed through a 

 series of rings round the neck. G- is coarse material. H, Swiss silk or 

 such-like material. The end takes off at I, as in Hensen's net. Thus 

 by letting the whole apparatus down nothing enters the net, but on 

 hauling up the tow-netting proceeds and goes on vertically until the 



* Proc. Roy. Physical Soc, xv. (1904) p. 141 (5 figa.). 



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