SEA-FISHERIES LABORATORY. 219 



and it is by no means always the two hauls that are most 

 alike in bulk that agree best in the kind and number of 

 organisms. 



On reflection, it will probably be agreed that it is 

 unlikely that, with the large, varied and irregularly 

 scattered population that we find the sea to contain, two 

 nets should often catch the same quantities of the same 

 sets of organisms. Consequently a result like that 

 obtained on April 22nd (Form 45), where the two nets 

 caught precisely the same amounts, and where the lists of 

 organisms constituting the hauls are almost exactly alike 

 both in kinds and numbers, is interesting. It will be 

 noticed how different the catch of the weighted net 

 (exactly similar to B and C but ranging through a lower 

 level of water) was on this occasion. The shear-net being 

 of much larger size and having a much coarser mesh 

 naturally gave very different results. It is not comparable 

 with any of the other nets. 



As an example of a case where two similar nets, 

 hauled side by side on the same occasion, gave very nearly 

 the same amount of material, but where the kinds and 

 numbers of organisms present in the catch when examined 

 were found to be very different, I give the following lists 

 of the contents* of the two surface nets after a 15-minutes 

 haul on April 13th, 1907, at Station III. The one net 

 contained 16 c.c. and the other 15*5 c.c, but these amounts 

 were made up very differently in the two cases. For 

 example, it will be seen that in the net C there were no 

 Balanus nauplii and no immature Copepoda, while 

 thousands of both were present in B. Then, again, in B 

 there were very few adult Temora, while in C practically 

 all the Temora were adult. The lists will show other 



* Only omitting those organisms of which fewer than ten individuals 

 were obtained. 



