ANIMAL CHLOROPHYLL 359 



species of echinoid whose blood-cells have been reported upon, 

 the existence of a red, or red-brown pigment cell (such as was 

 described for the Bermuda sea-urchin) has been noted ; and 

 a careful study of the epidermal pigment would undoubtedly 

 reveal, as it did inT. esculentus, that it is identical with 

 that of the coloured amoebocytes. 



Holothuroidea. — The paper of MacMumi (1889) on 

 animal chromatology contains many valuable observations con- 

 cerning the pigments ofHolothuria nigra. He has shown 

 the presence of a red lipochrome in the ' blood ' of this form and 

 has found an identical substance in the integument. He identi- 

 fied the same pigment in the digestive gland and concluded that 

 it ' is built up in the digestive gland and carried in the blood 

 current to be deposited in other parts of the body, though what 

 its role may be when deposited there it is difficult to say '. The 

 fact that this pigment is found in the digestive gland is of 

 particular importance, and should be borne in mind when the 

 pigmentation of the crustaceans is considered. In passing, it 

 seems worth while to note that this red lipochrome described 

 by MacMunn is the one which Harvey (1915) found in the testis 

 of Stichopus ananas, on which he has performed an 

 interesting series of permeability experiments, using the lipo- 

 chrome within the cells as an indicator.^ The writer has 

 observed amoebocytes with brown pigment granules in the 

 body -fluid of Holothuria surinamensis — pigment 

 granules which are similar to those of the epidermis. In 

 addition Herouard (1889) and Cuenot (1891) have reported 

 brilliant brown and yellow amoebocytes for many holothurians 

 common along the French coast. One holothurian (Cucu- 

 maria planci, Marenz.) is distinguished by the presence 

 of haemoglobin in the cells of the perivisceral cavity. Koll- 

 mann (1908, p. 188) endeavoured to find the origin of these 

 cells, but was unsuccessful.^ 



^ The substance turns blue in acid (MacMunn, 1889 ; Harvey, 1915). 



2 Haemoglobin is found also in the ophiuroid, Ophiactis virens 

 (Foettinger, 1880) ; derivatives of haemoglobin (actiniohaematin), more- 

 over, are found in many actinians. 



NO. 262 C C 



