METHODS OF COLLECTING AND PHOTOGRAPHING 



75 



the inside of the band, with its margin turned back over its outer 

 surface for the fraction of an inch. By this construction the canvas 

 cone folds conveniently for transportation, while the inner surfaces 

 of cone and net are continuous and smooth, so that plankton 

 organisms do not readily lodge 

 on them. If convenience in 

 transportation is not important 

 the cone may be better made 

 of sheet brass. 



TVlP original fpatlirP of this FlG - l8 - Bucket of Wisconsin plankton net. From 



apparatus loaned by Professor Birge. At right is one 



rift ic tVip HnrL-ft fFio-c rR snrl of the writer's tubes for filtering plankton. Forde- 

 DUCKCt Ulg S - J anc scriptions see text. (From original photographs.) 



19), which is made of telescope 



tubing of two sizes. The smaller size (two inches in internal 



diameter) is used to make the headpiece shown attached to the net 



m Fig. 17. This (Fig. 19, a) is one 



| and three eighths inches long and is 

 i fastened to the net by means of a 

 brass band clamp (Fig. 19, b) made of 

 ' two pieces, with wings at the ends 

 ; through which pass clamp screws. 

 A pin soldered into the headpiece 

 fits a hole in each half of the clamp 

 1 and prevents its turning when the 

 R h I > bucket is twisted to remove it (seen 

 | near the upper margin of Fig. 19, a). 

 ** giV.-ja*'-' d Three brass rings soldered to the out- 



j side of the band clamp serve to attach 

 cords which extend to the lower sup- 



Fl c G ons?n S^?S b ttS^ W t P rtin S g f the CaI1VaS C0ne aild 



S^^KSt^^SSf carry the weight of the bucket. 



clamps with screws; g, side clamp in posi- .-r,, 7 . /-.-i. \ j f i 

 tion; h, semi-cylindrical rod soldered to The bucket (Fig. 1 8) IS made of tele- 

 strip between windows; i, stem of the plug . .. . . . 



which closes the spout seen below at left of SCODC tubing Of a S1ZC which fits OVCr 

 c; j, millimeter scale. For description see 



p a - that used for the headpiece. Pieces 



are cut from the sides of this so as 

 to form four windows separated by strips about one-half inch wide. 

 These strips are strengthened by soldering to the inside of each a 

 semi-cylindrical rod about one-quarter inch in diameter (Fig. 19, h). 



