182 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



of this singular, abnormal phenomenon, and showing that the discolora- 

 tion first affects the mobile tissues of the animal contained in its vessels, 

 that is, the blood cells and the watery serum in which they float, was 

 the histological and physiological part of the problem. MM. Puys6gur 

 and Decaisne did uot apparently perceive that they were dealing with 

 a pigment which was not truly chlorophyl. This fact the writer would 

 again point out, giving reasons therefor which he has not hitherto 

 stated elsewhere : 



1. The discoloration is progressive in its advance from the vascular 

 system to other parts, the gills being first affected, then the heart, and 

 finally the mantle and body-mass. The discoloration is diffuse, not con- 

 fined to chlorophylloid granules, as iu plants or in other animals in which 

 such distinct granules are actually found. Nor is it ever in any case 

 lodged iu corpuscular bodies of any sort, except throughout the whole 

 body of the cells found in the vascular canals or the cells entering into 

 the formation of the edible connective tissues of the oyster. This ten- 

 dency gradually to diffuse itself shows that this pigment must be in 

 solution in the blood-serum. The experiments of MM. Puysegur and 

 Decaisne show that it is not destroyed in the process of digestion, as 

 chlorophyl seems to be by the action of the gastric juice in the stomacli 

 of vertebrates, in which case it never, at least in herbivorous forms, 

 has been known to discolor the blood. Chlorophyl in plants is contained 

 iu intracellular plasmic bodies, which are not destroyed when the color- 

 ing matter is removed. Sachs* says : " The coloring matter contained in 

 each chlorophyl body is itself only extremely small iu quantity; after 

 its removal the protoplasmic basis retains not only its form, but also its 

 previous volume. The latter is always a continuous soft substance, 

 containing extremely small vacuoles, in which the coloriug matter is 

 generally distributed universally, though not always uniformly.'' The 

 diffuse coloration of Stentor eceruleus amongst infusorians seems to be 

 somewhat similar to the "azure blue" color found by PuysC'gur in the 

 " intracellular liquid " of Navicnla ostrearia. This brings us to the con- 

 sideration of the second piece of evidence opposed to the conclusion 

 that the pigment which discolors clams and oysters is chlorophyl. 



2. The discoloration of the flesh of the clam and oyster is uot 

 distinctly green, but bluish-green. Only at times have I observed 

 that the blood-cells lodged in the heart were of a light pea-green color 

 in the latter. This bluish-green color I have seen very strong^ ex- 

 pressed in Ostrea angulata and in specimens of 0. edulis. It is, there- 

 fore, reasonable to conclude that the pigment, which is imbibed by the 

 plasma of the parts affected, is truly something different from ordinary 

 green chlorophyl. Phycocyauin, or a kindred vegetable pigment, as 

 elsewhere stated, seems to be the substance which is absorbed by the 

 tissues affected. 



* Text-Book of Botany, 2d Eng. ed., p. 45, 



