Figure 17. — Two-way, double action valve on syringe (see Table 1 for source of supply). Usually 

 the valve is fixed to the syringe by a screw-on action. In this illustration, the valve is fitted tightly 

 by friction to a disposable plastic syringe. 



Figure 18. — Labels for plankton samples. Clockwise 

 from upper left — Tie-on cardboard label on 1-quart (1 

 liter) bail-type jar; screw-on cap labeled with Martek 

 pen, on 1-pint (1/2 liter) jar; self-adhesive label on 

 screw-on cap; inside label on which information dupli- 

 cates (not in any of these cases) whatever is written on 

 an outside label. Inside label is made of 32-lb., chem- 

 ically resistant linen called "Resist-all." 



Amount of clogging — should be checked 

 in one of the appropriate boxes. This 

 is best observed by noting the variation 

 of the meter readings (see 3b above). 

 If washing is needed, one of three meth- 

 ods may be used : ( 1 ) The net is everted, 

 still on its ring, and brushed down with 

 an ordinary sweeping broom and run- 

 ning seawater; (2) rings are stood on 

 edge, net is tightened along its length 

 by tying down end (without cod end at- 

 tached) and hosed down with high-pres- 

 sure fire hose. This is very effective 

 provided that plankton has not dried in 

 the meshes; (3) net is detached from 

 ring and put in a washing machine using 

 a 30-min cycle, warm water (not hot) 

 and a nonpolluting detergent. 

 Rips and holes in the net — the net should 

 be looked at after every tow to check 

 on needs for repair or replacement. If 

 holes or tears are small, they should be 

 sewn before the next tow with nylon 

 thread of a dark color (to be easily lo- 

 cated for sewing machine repair later 

 on shore) . Check appropriate boxes. If 



18 



