292 Comparative Animal Physiology 



TABLE 48 (continued). DISTRIBUTION OF PIGMENTS IN BODY FLUIDS 



cally among the arthropods, e.g., Daphnia, Cheirocephalus, and Branchipus, 

 and in the larvae of certain chironomids. Among the echinoderms hemoglobin 

 is also found in nucleated corpuscles in the sea cucumbers, such as certain 

 species of Thyone and Cucumaria. Cncnmaria elongata, a mud-dweller, has 

 hemoglobin, whereas Cucumaria saxicoia, which lives among rocks, with 

 greater oxygen availability, lacks hemoglobin."' In a few nemerteans and 

 parasitic flatworms and in several roundworms hemoglobin has been detected. 

 The properties of the hemoglobin in some of these parasites are distinctly 

 different from those of the hemoglobin in the host. 



In addition to the blood hemoglobins, there are also many tissue hemo- 

 globins. Muscle hemoglobin or myoglobin is abundant in the "red" muscle 

 of mammals and birds, in the heart muscle of all classes of vertebrates, and in 

 scattered skeletal muscles of cold-blooded vertebrates, as in the dorsal fin muscle 

 of Hippocampus.^'^'- In JJrechis hemoglobin is present not only in coelomic 

 cells but also in muscle and nerve cells." Myoglobin occurs in the radular and 

 pharyngeal muscles of certain snails, especially Busycon/' in the ganglion 

 cord of Aphrodite, ^'^- and in ganglia of certain nemerteans.'-*^ A similar pig- 

 ment is found in the "tracheal body" of larvae of the fly Gastrophilus, which 

 is parasitic in the stomach of horses, and also in the tracheal cells of some other 

 insects."'' Hemoglobin has even been reported from Paramecitnn.'^^^ Hemo- 



