PLANKTON STUDIES AND THEIR UTILITY. 283 



offers the rarest opportunity for this kind of investigation. This region 

 should be studied in such a way that the work done will be valuable refer- 

 ence when compared with changed conditions which are sure to come 

 later. 



All water life is divided into two great classes by no hard and fast 

 lines. These are littoral and pelagic. The former has to do with life 

 on or near the shores. The latter deals mostly with the floating life of 

 the waters, and it is included in our plankton studies. The term plankton 

 is applied to the plant and animal life that moves with the currents. 

 Floating algae and such minute swimmers as the microscopic Crustacea 

 would be included, while fish and other free swimmers would be excluded. 

 It is an occasion of surprise to some to find that the quantity of such 

 matter in any large body of water is so great that the fixed plants along 

 the shore, and the animals they harbor, are comparatively insignificant 

 in a consideration of the total life. 



The number of individuals in a lake like the Flathead is beyond com- 

 prehension, and the number of separate species is large. The quantity 

 of life if collected in one mass would weigh thousands of tons. 



We know that the total amount varies greatly from season to season, 

 and it will be soon shown that there is reason to believe that there is 

 quite a range of variation in the relative numbers of organism from 

 year to year. 



We are learning something of their daily movements in summer. To 

 undertake the studies of quantity and composition requires additional 

 means of transportation, apparatus time, and literature, and an infinite 

 supply of patience. Time and patience can not be purchased in the mar- 

 kets, so the plankton student must bring these with him. 



If you care to malve the trip go with me in the Missoula and we will 

 push over to Station B. This location will be plain enough to you if you 

 take the bearings. Station B, is at the crossing of two imaginary lines 

 drawn one from the point of the delta to the club house, and one from 

 the rocky point in the bay, down the middle of the bay. (See Plate 

 XLVIII). The other stations are located by a similar method. From 

 soundings we find we have eighty feet of water. The temperature at the 

 surface and at various depths, the time of day, the nature of sky and 

 water are recorded. The Kofaid net of fine bolting silk is then carefully 

 adjusted over the side of the boat, and the pump and hose made ready to 

 use. 



Pumpings are now made at the surface by holding the end of the hose 

 from one to three inches from the top. This catch is put into carefully 

 labelled bottles with numbers corresponding to those in a note-book, 

 where the data before mentioned are kept. The plankton is preserved 

 in a one per cent solution of formaldehyde. Other pumpings are made 

 at three, seven, fifteen, twenty-five, fifty feet, and to the bottom, and the 

 collections properly labelled. We then proceed to similar operations at 

 the other stations. 



We have endeavored to make daily collections the past two years 

 while the station is open. You can readily see how valuable would 



