HEMOGLOBIN IX'THYONE BRIAREUS LESUEUR. 1 



HAN C. VAN DER HEYDE.^ 



Hemoglobin is by no means rare in lower animals. Though it 

 was originally thought to be characteristic for the vertebrates, it 

 has been found in many other instances. Even in animals as 

 low in the scale of phylogenesis as the worms, we find it in very 

 many forms either in the coelomic liquid, as in the common earth- 

 worm, or in corpuscles (Glycera, Capitclla, Plioronis, etc.). 

 In Molluscs and Arthropods it is generally found in the free 

 form. It is chiefly found in mud-dwellers, or more in general, in 

 animals living in a medium in which oxygen is scarce. The larva 

 of Chironomus is a classical example. 



Our knowledge of the occurrence of respiratory pigments in 

 Echinoderms is very incomplete. In one case, in the brittle star, 

 Ophiactis t'ircns, hemoglobin has been found. Other statements, 

 e.g., the assumption of a respiratory function of the so-called 

 '"' echinochrome (Mac Munn. 1885.) '' in Echinus and Strongylo- 

 centrotus, are to be accepted with some scepticism. Winterstein, 

 e.g., could show that a solution of echinochrome did not take up 

 any more oxygen than the same amount of sea water. Other 

 data concerning respiratory pigments in Echinoderms have not 

 come to the writer's knowledge. 



In studying the digestion of the Echinoderms, among which 

 Th\onc briarcus, a dendrochirote Holothurian common around 

 Woods Hole, the writer was struck by the brilliant red color of 

 the Polian vesicles every time he dissected a specimen. Curiosity 

 drove him to examine this color a little more closely. The color 

 appeared to be due to the contents ; it " flows away," when the 

 vesicle is cut. It could be centrifuged off and a microscopical 



1 From the Marine Biological Laboratory, Woods Hole, Mass. 

 Received for publication August 30, 1921. 



2 The writer wants to express his indebtedness to Dr. Leo Loeb and Dr. 

 Samuel E. Pond for the loan of microscope and spectroscope and to Dr. 

 Hiroshi Oshima for morphological information. 



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