63 



MARVIN ALLUM 



(Slide FG-26) 



This, then, is diluted £or much the same 

 reason that the egg suspension was diluted initially and 

 that is to get the 20,000 to 30,000 now larvae diluted to 

 the point that a countable sample can be taken. 



(Slide FG-27) 



As you see here, then, an aliquot of this 

 dilution is taken-- 



(Slide FG-28) 

 --placed in a small vial and a little formalin is added 

 to preserve the sample until the counts can be made. 



(Slide FG-29) 



Later on the sample is transferred again 

 to a microscope slide and-- 



(Slide FG-30) 

 --with the compound microscope we examine the straight 

 hinge larvae that result after 48 hours of incubation at 

 20 degrees. In the lower right-hand corner is a larva 

 which would be counted as normal. The next to the last 

 on the left lower would also be counted as normal. All 

 of the other larvae shown here show some evidences of 

 abnormality. In actual practice, the criterion that was 

 used was whether or not shell development was adequate and 

 covered the soft parts of the larval body. Even though 



