358 JOHN F. FULTON, JR. 



is a reduction product of haemoglobin. It is interesting also 

 to note that MacMunn (1883 h) has shown the presence of free 

 haematoporphyrin in the tissues of echinoderms (especially in 

 Uraster rubens) which, as he suggests, is probably an 

 intermediate product in the formation of echinochrome. 



From the preceding facts it is evident that in most echino- 

 derms there are present simultaneously chlorophyll, haemato- 

 porphyrin, and echinochrome, the last being closely related to 

 haemoglobin. If the diagram on p. 351 be consulted it will be 

 o])served that this represents almost the complete circle from 

 chlorophyll to haemoglobin : thus we have chlorophyll, 

 a porphyrin, and an iron-containing pigment which breaks 

 down into a reduction product of haemoglobin. This evidence 

 greatly emphasizes the hypothesis (p. 352) that many of the 

 animal pigments, including haemoglobin, are derived originally 

 from chlorophyll. 



(h) 1 h e r E c h i n o d e r m a t a . 



The body-fluids of numerous other echinoderms possess 

 coloured amoeboid cells whose pigment in many cases appears 

 to be identical with that of the epidermis. The fact that the 

 colour of these cells is similar to that of the body is in itself 

 significant ; in addition, however, there is frequently chemical 

 evidence which tends also to establish their identity. To avoid 

 tiresome repetition only a few of the more important examples 

 from several of the classes of echinoderms will be given. 



Asteroidea. — The amoebocytes from the coelomic fluid 

 of starfish possess granules which vary in colour from yellow 

 to a deep brown (Cuenot, 1901). It is noteworthy, moreover, 

 that the cells with the darker granules are found in the animals 

 with a deeper body-colour. This is particularly noticeable in 

 some of the Bermuda starfish. 



Ophiuroidea .—The only species examined was p h i o - 

 coma pumila. In this form the body-fluid was marked by 

 the presence of many yellowish-brown pigment cells which 

 were closely allied in colour to that of the disc. 



Echinoidea. — So far as the writer is aware, in every 



