346 THE AMERICAN MONTHLY [Nov 



Plankton Nets. — The distribution of aquatic life from 

 season to season throughout the various zones of the plank- 

 ton in the larger masses of water of the globe is an object 

 of study which has received considerable attention at the 

 hands of investigators during the last decade. The great- 

 est difficulty that has been experienced has been the need 

 of apparatus upon which the operator can rely to work sat- 

 isfactorily under all conditions and at all times of the year. 

 The nets that are usually used cannot claim these advan- 

 tages, inasmuch as they are always liable to damage and 

 loss when working on a rocky bottom, and during the win- 

 ter months, when the plankton yields its most interesting 

 results they are inadmissible in northern latitudes owing 

 to floating ice. The accuracy of the results, too, leave 

 much to be desired, as with the net it is not possible to de- 

 termine exactly the volume of organisms actually present 

 in a given quantity of water, nor is it practicable to deter- 

 mine the variousgroups that are characteristic of the many 

 vertical zones or strata of water of which the plankton is 

 constituted. 



Plankton Pump. — For critical work, nets have had to be 

 discarded, and in place of them Dr. H. B. Ward has used 

 during his recent investigations on the Great Lakes,a light 

 weight force pump which he calls the "plankton" pump, 

 and which can be carried about and operated by one per- 

 son. The cylinder of the machine is eleven inches long by 

 three and a half inches in diameter, and it has a capacity of 

 three hundred and forty-seven and a half cubic inches per 

 stroke. It is essentially an ordinary force pump, save that 

 it has very finely ground check valves, to which, it is be- 

 lieved, the accuracy of the working of the apparatus is 

 largely due. The pump is connected with the water by a 

 hose one and a half inches in diameter, the lower end of 

 which is adjusted to the various vertical zones of water by 

 means of an attachment to a floating block. Most gratify- 

 ing results have attended the use of this apparatus. It is 

 possible to measure with great accuracy the amount of 

 water filtered. Collecting can be carried on without any 

 disturbance of the water,and water can be drawn from any 



