9 



adapter in the right hand holder. It is a metal tube, fitted with rubber washers 

 and screw caps at both ends. One end, A, carries the pipette, the other, B, forms 

 a junction v/ith the injection tube.'' At A there is also a metal washer, W, one end 

 of which is concave. Care must be taken to see that the rubber washers fit snugly; 

 and that the rubber washer at A is inserted first. The concave end of the metal 

 washer must always face the rubber. The adapter is constructed as shown in the ac- 

 companying diagram. (Figure 0). 



A W 



i msmr* ? f 



-vC 



Tg g 7/ W f^V 



c.c.a 



Fig. 2 



To prevent tension on the adapter and clamp, loop the tubing back of the adapter, 

 until all strain is removed. Fill the entire system with dust-free distilled water, 

 which has been recently boiled to reduce air content. Fit into the adapter a piece 

 of sealed off capillary and screw in tightly. Exert enough pressure on the plunger 

 to be certain that there are no leaks. Leaks may occur (a) at the point where the 

 syringe fits into the hypodermic needle, (b) at the point where the metal tubing 

 enters the adapter, (c) where the capillary enters the adapter. If there is leakage 

 at (a), work syringe and hypodermic together until they fit more tightly. If there 

 is leakage at (b) or (c) it may be due to the absence of the rubber washer which 

 should be in this position, or due to an imperfect fit of these washers. Remedy all 

 defects until you have a water- tight system. 



Mount a microneedle in the left hand holder. Center and focus as usual. Empty the 

 syringe until it is but three-quarters full. Then insert a micropipette in the left 

 hand holder, and fasten securely. Press on the plunger. If the system is water tight, 

 water will partially fill the shaft of the pipette. If the pipette tip has been 

 broken by any chance, this water will be driven out of the pipette tip. Discard such 

 a pipette. If the tip is sealed the water will recede into the adapter on release of 

 pressure. Now set the pipette into position using the microneedle as a guide. 



Place, a drop of distilled water on a cover slip, invert and put in place on the 

 moist chamber. Rack the moist chamber forward. Using objective #3b, focus on the 

 edge of the hanging drop. Carefully raise the pipette into the drop with the fine 

 adjustment, until the pipette tip touches the cover slip with sufficient force to 

 break onl|r the tip. Attempt filling the pipette by pulling back gently on the plunger. 

 Then lower the tip, move it out of the hanging drop, and see whether fluid can be 

 expelled by exerting slight pressure on the plunger. If the tip is not broken, re- 

 peat this procedure until successful. Rinse the tip by filling and emptying it sever- 

 al times to rid it of free alkali. Always break the tip of the pipette at the magnif- 

 ication under which it is to be used. 



Your apparatus is now ready for operation. Compare and check your set-up with the 

 one shown in the frontispiece. It is advisable to read the following references 

 to familiarize yourselves with the general morphology and behavior of the organ- 

 isms to be used for experiments. 



