443 



difficult to remove so many scales without injuring tlie skin. Two fisli 

 suffered slight punctures in the operation and died of sporozoan infection 

 two days later. Tlie other three lived until the close of the experiment 



The scales regenerated to almost their normal size in twenty-five days. 

 The rate will probably be found to vary in different species of fish. I was 

 unable to dissect out the scales before the sixth day after the operation. 

 On tliis date the scales were very thin and fragile; the cycloid sculpture 

 was developed to the extent of three irregular yet fairly distinct lines 

 which surrounded a relatively large unsculptured area. 



The radiate sculpture which the normal scales of this fish have on 

 their inner ends could not be detected on the sixth day. Faint traces of 

 it appeared on the eighth and tenth days and by the twelfth it was very 

 evident. From the twelfth day the sculpture developed as it does on the 

 periphera of a normal scale except that the lines of the cycloid sculpture 

 were slightly farther apart. 



Scales from the largest of series A, 114 num., the smallest in series 

 B, 72 m.m., and one of the fish that had all its scales removed are figured 

 in plate III. These show no marked difference in the differentiation, indi- 

 cating that age and degree of injury do not influence the process to any 

 great extent, if at all. 



It may be noted that no fatalities occurred which were referable to 

 the osmotic pressure of the sea water. This fact is in direct opposition 

 to the findings of Garrey, '0.1, but corroborates in part those of Sumner, 

 'OG, who repeated and extended the work of Garrey. The results may bo 

 harmonized by assuming that sporozoan infection occurred in Garrey's 

 experiments of which he took no account. The histological study of this 

 process has not yet been completed. 



Garrey, W. E. 



'05. The osmotic pressure of sea water and the blood of marine ani- 

 mals. Biol. Bull. Vol. VIII, No. 4. 

 Hoffbauer, — . 



'99. Die Altersbestimmung des Karpen an seiner Schuppe. Jahres- 

 berichte des Schlesischen Fischerei-Vereiu. 

 Hutton, J. Arthur. 



'10. Salmon scale examination and its practical utility, with notes 

 on Wye salmon fisheries and the photography of the scales. Sherratt and 

 Hughes, London. 



