HEART-BODY, ETC., OF CERTAIN POLYCHJITA. 281 



tiori, are not chitin ; that they are not guanin, since they give 

 no murexide reaction (in these points they differ from botli 

 kinds of chloragogen described by Schaeppi in Ophelia) ; that 

 the ovoid crumpled structures are chitinous bodies ; that fat 

 is distributed in globules in the heart-body, especially in its 

 periphery; that iron is distributed in larger and smaller 

 granules, also especially in the periphery ; and finally, that 

 glycogen is probably absent. 



Before leaving the Cirratulidae the relation of the heart- 

 body to its surroundings suggests several matters for con- 

 sideration. On passing out of the dorsal vessel the great bulk 

 of the blood must first go to the gills ; so that if the heart- 

 body in any way modify the constitution of the blood, that 

 change has probably some relation with the respiratory organs. 

 In connection with this point it is interesting to note the 

 pigment lymph-glands described by Ed. Meyer (24, B, p. 701) 

 on the blood-vessels, particularly the arteries, of the gills of 

 Cirratulidae. They consist, he says, of a single glandular cell- 

 layer belonging to the peritoneal wall of the respiratory 

 vessels, and contain brown pigment.^ He also mentions them 

 in Terebellidae (p. 645) and elsewhere. His view with regard 

 to them is that they take some fluid ingredient out of the 

 blood, and cast it into the coelomic fluid. This theory, 

 however, does not account for the situation of the organs in 

 the gills. Is it to be inferred that the excretory matter is cast 

 to the exterior through the gill-wall ?2 At any rate, gill 



> Iron-holding patches, scattered at some points in the epidermis of the 

 gills, are demonstrated both by the Prussian blue and the ammonium sulphide 

 reactions ; the iron is removed by Bunge's fluid at 60" C. in an hour. No 

 iron reaction was noticed in the pigment lymph-glands. 



2 Gill glands for excretory purposes have been demonstrated by Allen (1) 

 in Crustacea ; whilst amongst Annelida yellow concretions regarded as cer- 

 tainly excretory have been found by Miss Buchanan (8, C) in the gills of a 

 branchiate Polynoid. She finds a similar phenomenon in several other worms. 

 In sections of the posterior gills of Sternaspis I find numbers of small 

 refringent bodies crowding the epidermal cells. It may be suggested that 

 the important functions of the dorsal pores of earthworms, of removing waste 

 products, may be represented iu branchiate worms by an excretory activity of 

 the gills. 



