[19] EGGS OF THE PLAICE, FLOUNDER, AND COD. 445 



make comparisons of the different stages of development and of the 

 different species of fish. Nets of the breadth of one meter should be 

 used, so that, after the eggs have been counted, there is no risk of be- 

 ing hindered by calculations from making the best possible use of fine 

 weather. 



The bottom-net referred to in my observations can, probably, be better 

 arranged for quantitative investigations. The results which I obtained 

 with this net hardly give the number of eggs high enough. Such a net,^ 

 moreover, can only be used when the sea is very calm, as the waveS' 

 disturb the even movement very much. This might be remedied by 

 tying a weight to it. 



I have based my calculation on the supposition that the water passes 

 through the opening of the hoop of the net, just as if there was no net,. 

 This is, of course, not absolutely correct, because the meshes of the net 

 offer resistance to the water. It is my opinion that all water, with the 

 exception of a very small quantity in front of the net, goes through it,. 

 when the motion is slow ; for my observations showed that objects float- 

 ing in front of the net did not avoid it. So far I have not been able tO' 

 discover any way to utilize the water which avoids the net. It is, how- 

 ever, sufficient to know that, in consequence of this circumstance, one- 

 has obtained a catch which is too small in proportion to the fishing area. 

 The length of the area is obtained by means of a log with a line divided 

 into meters (a white rag being fastened to the line at every two meters,, 

 and a different-colored rag at every 10 meters). 



Besides the apparatus mentioned, another net is required, with which 

 fishipg can be carried on at full, or at any rate, half-steam power. The 

 apparatus required is one which will decrease one-tenth the velocity of" 

 the current passing through the mull -net at the rate of 10 kilometers per 

 hour. For this purpose I have had constructed a hollow cane with au; 

 obtuse top, made of wicker-work, the base of the cone also being closed 

 by wicker-work. The dimensions of this apparatus were as follows:; 

 Diameter of opening at top, 8 centimeters ; diameter of base, 32 centime- 

 ters; depth, 25 centimeters. In the hoop is placed a mull-net of similar 

 shape. The whole is supported by a pole and rope attached to the prow 

 of the vessel. I intend to still further improve this apparatus ; but even 

 in its present condition, it retains alive and well a portion of the medusae 

 and crabs which have been caught, even if the current should have a 

 velocity of 9.7 kilometers per hour. So far, this apparatus cannot yet be 

 used' for catching large quantities, but it can direct attention — through 

 different particles adhering to it— to every change in the character of 

 the contents of the water. 



A second condition of a successful method is the possibility of ascer- 

 taining immediately and quickly the quantity and quality of the catch j, 

 for only by the possession of this knowledge can systematic observa- 

 tions be carried on. 



As the nets have to be washed, a good deal of water— at least 3 to 4 



