microswitch actuated a solenoid valve in the vacuum line and the other a similar valve 

 in the air line. The remainder of the unit consisted of a flat-bottomed plastic petri 

 dish (P), 6 inches in diameter. 



P 



Figure 5. --Mechanical egg planter: (K) Circular brass chamber; (L) stainless- 

 steel hypodermic needles; (M) one of three adjustable legs; (N) one of two copper tubes 

 soldered to top plate of chamber; (O) two microswitches for activating solenoid valve in 

 vacuum line and one in air line; (P) petri dish. 



To pick up eggs with the planter, the operator first deposited the eggs in sterile 

 water in the petri dish, placed the egg planter in the dish, and actuated the vacuum 

 while moving the planter around the dish. As the ends of the needles contacted the eggs, 

 the eggs were drawn to the needles and held. When each needle tip had picked up an 

 egg, the operator removed the planter from the dish and held it over the larval medium. 

 A short blast of compressed air then forced the eggs onto the surface of the medium. 



Excess water drawn into the egg-planter chamber in the process of picking up 

 the eggs was removed by the vacuum line. The only water deposited on the medium 

 was the small amount retained in each of the needles . 



