The formaldehyde further denatures the 

 proteinaceous components and causes the 

 worms to appear opaque and whitish in color, 

 suitable for rapid enumeration against a 

 dark background. 



Evaluation of the Procedure 



The relative efficiencies of recovery 

 of the parasites by the dissection method 

 and by the peptic digestion procedure first 

 were evaluated. Thirty-nine chum salmon 

 ( Oncorhynchus keta ) , obtained from various 

 areas of the North Pacific Ocean, were 

 used. The right sides of the fish were 

 treated by dissection and manual isolation 

 of the worms; the left sides by peptic 

 digestion. The results of the study are 

 presented in table 1. 



The data in table 1 were analyzed 

 statistically with the "t" test for the 

 difference of mean values (Johnson, 1950). 

 The population of worms isolated by dis- 

 section was found to be significantly less 

 (t = 2.03, N = 39, significant at P = 0.25) 

 than that determined by the digestion 

 procedure. 



The possibility existed that the dif- 

 ference might have been due to dissimilari- 



of the worms between the left and right 

 sides of the fish. To determine which of 

 these possibilities was most probable, a 

 second study was initiated. In this study, 

 15 chum salmon were used. The parasites 

 in both the right and left sides of each 

 fish were first dissected and removed for 

 enumeration. The dissected material then 

 was treated by peptic digestion, and the 

 residual entire worms in the flesh were 

 isolated and counted. The data, which are 

 independent of these in table 1, are pre- 

 sented in table 2. 



A statistical analysis of the data, 

 again using the "t" test for the difference 

 of mean values, demonstrated that the num- 

 ber of parasites determined by the dissec- 

 tion method alone was signif iceintly less 

 (t = 3.26, N = 15, significant at P = 0.01) 

 than the total number counted, i^.e,, the 

 number determined by dissection plus the 

 additional number recovered by digestion of 

 the dissected material. 



The mean difference between the total 

 number counted and the number obtained by 

 the dissection of the fish was taken as an 



Table 2.-- Anisakis sp. count by dissection, digestion 

 of dissected material, and total count. 



(Summation of the two independent determinations) 



