GERMAN PLANKTON INVESTIGATIONS. 333 



but of Codonella campanula the whole were retained. With 

 regard to the eggs, only 19 per cent, of the egg sacs 

 of the Copepoda were lost, eggs (of 81 \l diameter) with 

 a shell, as well as eggs (127 p diameter) with a soft 

 membrane, were invariably retained. 



With regard to the invertebrate larvae, young larvae, 

 with a ciliated ring, invariably escaped capture. Of Cope- 

 pod larvae 14 per cent, escaped. With regard to the larger 

 and more important animal constituents of the Plankton, 

 a decided improvement is noticed. Of adult Copepoda 

 only one-third per cent. (0*3) escaped capture, while 

 Evadne, Podon, worm larvae with long bristles, Sagitta, 

 young mussels and gastropods, Cyphon antes, Oikopleura, 

 and (?) Planida were invariably totally retained by the silk 

 cloth. 



It is thus seen that the individuals which escape play 

 a small and insignificant part in the total volume or weight 

 of the plankton, while the larger and more important 

 individuals are invariably retained. 



Kofoid's results, being based on observations made on 

 fresh water plankton, are not directly comparable to the 

 results obtained from the sea, since the nature of the 

 plankton is in both cases very different, in the former con- 

 sisting to a much greater extent of the very smallest Algae 

 and Protozoa. 



The Latest Form of the Plankton Nets. 



To meet the objections raised by Kofoid, which were in 

 a measure substantiated by the experiments of Lohmann, 

 Hensen (11) has devised two nets which will capture the 

 smallest organisms in the plankton, and which are briefly 

 described below. These nets, being protected externally 

 by a strong metal covering can be used from a steamer 

 which is travelling at a fair rate of speed. 



