Table 5 shows the results of absorption 

 tests of normal bovine serum with the cells of 

 selected skipjack. This table shows the reac- 

 tions of normal bovine, 1 in 8 dilution, and of 

 normal bovine, 1 in 4 dilution, absorbed with 

 selected cells. The letters a, b, and c after 

 the absorptions with No. 13' s cells show the 

 results of separate absorptions. The observa- 

 tions conform with the concepts that fish Nos. 



10, 12, 14, 15, 17, 18, and 19 carry an antigen 

 (2) on their cells that reacts strongly with anti- 

 bodies in normal bovine serum, and that fish 



11, 13, and 16 lack this antigen. 



Table 6 shows the results of absorbing 

 a mixture of normal sheep serum and albacore 

 No. 10 antiserum in final concentrations of 1 in 

 4 and 1 in 50 respectively. (Note that sheep 

 serum was used because the available bovine 

 serum supply was exhausted during the study. 

 Table 4 shows that the sheep serum contains 

 antibodies with affinities similar to those in 

 bovine serum, a point borne out by the absorp- 

 tions in table 6). The observations recorded 

 conform with the concept that fish Nos . 10 and 

 15 have both antigen 1 and 2 on their cells, fish 

 Nos. 11 and 13 have only antigen 1 on their cells, 

 fish Nos. 12, 14, 17, 18, and 19 have only 

 antigen 2 on their cells and fish No. 16 has 

 neither antigen 1 nor 2 on its cells. This con- 

 cept must of course be taken only as a guide to 

 further studies, involving larger series of fish. 



Comparative study of different species. 

 As noted above, single individuals of the follow- 

 ing species of fish were available for serologic- 

 al study; yellowfin tuna or ahi, little tunny or 

 kawakawa, and wahoo or ono . These individuals 

 were not all available at the same time nor 

 concurrently with the skipjack, so that complete 

 use of materials for comparative study could 

 not be made. Table 7 shows the reactions of 

 the cells of various species with a series of 

 antiserums, prepared as described in materials 

 and methods. Consideration of this table shows 

 several marked contrasts in the reactions of 

 cells of different fish with the same antiserums. 

 Of particular interest are the albacore anti- 

 serums, for one alternative explanation of their 

 reactions is the possibility that individual varia- 

 tions occur in albacore antigens . Those tests 



marked with an asterisk (*) were run at 1 in 50 

 serum dilution rather than at 1 in 32 . The 

 cells of the wahoo had become quite fragile at 

 the time of the test and the readings may not 

 prove to be reliable . 



Titrations were run on certain anti - 

 serums using the cells of a yellowfin tuna and 

 a little tunny. These antiserums are marked 

 with a "dagger" (/) in table 7. Differential 

 reactions between the two species, paralleling 

 those recorded in table 7, could still be ob- 

 served at dilutions of 1 in 200 and 1 in 400 for 

 the serums concerned. 



As the little tunny is similar in its 

 reactions to skipjack Nos. 10, 11, 13, and 15, 

 it seems likely that these two species vary 

 intra specifically in similar ways, a point that 

 would not be unexpected considering their 

 rather close evolutionary relationship. Absorp- 

 tion of bovine and human typing serums 

 confirmed the antigenic distinctiveness of the 

 yellowfin and little tunny. 



EXPERIMENTS WITH FROZEN HEMO- 

 LIZED WHOLE TUNA BLOODS 



Natural antibodies . Research on tuna 

 bloods was begun at a time when fresh tuna 

 erythrocytes were not available, and when the 

 author had received a variety of samples of 

 frozen whole tuna bloods from the sources 

 credited at the beginning of this paper. Con- 

 siderable effort was therefore made to develop 

 techniques that would permit the detection of 

 individual differences in frozen, hemolized 

 whole blood. As reported in earlier papers 

 (Cushing 1952, a and b), individual variations 

 in the natural antibody content of these bloods 

 were discovered, notably with respect to the 

 agglutination of human type-B cells. The valid- 

 ity of these observations was confirmed by the 

 discovery of individual variations in the natural 

 antibody content of fresh, unfrozen oceanic 

 skipjack serums obtained in Hawaii. These are 

 shown in table 8 . 



No agglutinins for human cells or sheep 

 cells were found in a sample of 24 frozen alba- 

 core bloods, collected July 24 to 26, 1952, off 



