Scale: actual size 



Float (plexiglass 



Figure 21.— T-Guide and float, actual size (designed by J. R. Thrailkill, NMFS). This 

 is used to calibrate quart jars and to adjust volumes of plankton + preservative in mea- 

 suring plankton volumes. To use: the float, triangular section pointing up, is inserted 

 between the vertical limbs of the T-guide. The apparatus is placed in a calibrated jar 

 of plankton plus preservative and the horizontal limbs rested on top of the jar (also see 

 Fig. 20). Liquid is added or subtracted causing the float to move up or down until the 

 etched line on the float is between the etched double line on the T (see Fig. 22). The 

 coincidence of the lines indicates that the proper level has been reached, i.e., the volume, 

 in millimeters, etched on the jar — accuracy ±: 1 ml. 



5. Large jellies and tunicates are removed 

 (estimated as equal to or larger than 5 ml 

 in volume) , vi^ashed, and placed into a grad- 

 uate with a known volume of 5Sr buffered 

 Formalin. The difference in this reading 

 and the known volume of added solution is 

 the Volume of the Large Organisms which 

 is subtracted from the Total Volume and 

 recorded as Total Volume Minus Large Or- 

 ganisms (Fig. 20). 



6. The drained plankton and the large organ- 

 isms are put into a pint jar(s) — see Note 

 below, and the jar(s) is filled with the ori- 

 ginal preservative. The original inside 

 label (s) is placed in the jar (s). If a screw- 



top quart jar is used at the time of collec- 

 tion, the same lid is used on the pint jar. 

 If that cap was marked with a writing pen 

 (Martek) or a self-adhesive label, it is left 

 as is. If a string label was used, as on a 

 bail-type jar, the top of the cap is labelled 

 with a self-adhesive label or Martek pen 

 (Fig. 18). 



Note: Pint jars are used to store measured plank- 

 ton because it has been found that almost 90% of 

 all single-jar samples on CalCOFI surveys will fit 

 into pint jars. Even if more than one pint jar 

 is used for some samples, the boxes for storing 

 this size jar require very little more than half the 

 storage space needed for quarts. 



Calibrated quart jars - with unmarked lids - 



are returned to wooden seagoing boxes (ca- 



22 



