only of the breaking of the subcutaneous capillaries and the blood 

 quickly coagulates , leaving only gray scars which persist for some time, 

 without any relation to the mortality of the f ish„ In fishes, broken bones 

 do not occur as frequently as they do in the case of injuries to human 

 beings,, and where they prove fatal it is usually the result of internal 

 bleeding caused by contusions Therefore, in this study the two first- 

 named types of inuries will be omitted,, and the mortality resulting from 

 the latter two will be discussed^ 



The result of brain contusions or the rupture of viscera is that the 

 large portions of the deep arteries and veins are broken „ The blood 

 running out of these vessels effuses into the tissues and, in fishes, it 

 finally reaches a condition where it can be seen from the outside If 

 these are observed inattentively, they are liable to be confused with the 

 minor lacerations and simple subcutaneous hemorrhages described above<> 

 Consequently it is understandable that hitherto all evidences of bleeding 

 appearing on the outside of the fish have been mistakenly, and without 

 deep consideration, believed to be simple external wounds , The author 

 has fortunately been able to distinguish them in this study, and has been 

 able to discover that brain contusions, ruptured viscera, and other types 

 of subcutaneous wounds are the main causes of the deaths which hitherto 

 have occurred several days after the fish have been captured. 



In the following paragraphs the motive for this discovery and the 

 results of the study will be explained, 



1) On the peak of mortality which appears several days after the bait 

 fish have been placed in captivity 



Fishermen who handle bait fish know very well from experience that 

 when fish are caught and held in captivity the mortality is extremely 

 small at first and that the peak of mortality appears after 1 or 2 days 

 have passed. They are so familiar with this phenomenon that when a 

 day or more has passed after the capture of the fish and the mortality 

 is gradually increasing, they indirectly forecast the jmminent appearance 

 of the peak mortality by such sayings as "Well, it looks as if the 

 sardines' heads have begun to ache, "XI Kiumra 24 ), w ho made a statistical 

 study of the mortality of bait fish, reported from actual cases that the 

 maximum values of tne death rate appeared after the passage of 1 - 2 

 days from the capture of the fish, and he gives a clear death rate curve, 

 as snown in Figure 10, 



The author, at Mito in Tagata-gun, Shizuoka Prefecture, in December, 

 1933, using as material sardines (average length 14,2 cm, average weight 

 25,1 gm) which had just been captured and which appeared to be compara- 

 tively uninjured, pierced the brain, liver, and spleen with a cannula to 



XI, Expression used by the Mito bait-dealer Mr, Yamamoto, as well as 

 many other commercial operators. 



36 



