2i8 PHYSIOLOGY OF THE INVERTEBRATA. 



(y) Comynactis nridis. — MacMi^rm has examined the red 

 specimens of this little sea anemone. On putting one of 

 these animals into a compressorium and examining it by 

 means of an achromatic condenser and a microspectroscope, 

 a spectrum was obtained whose bands do not correspond 

 with either those of actiniohgematin or actiniochrome, for 

 they are nearer the violet and diifer in other respects. Yet 

 they belong to a pigment which is related to actiniohsematin, 

 for this pigment can readily be changed into h£emo- 

 chromogen. No " yellow cells " are present in either the red 

 or green varieties of C, viridis. There is no doubt that this 

 anemone contains a respiratory pigment allied to actinio- 

 hsematin. 



The important researches of MacMunn and others have 

 shown : (l) That a respiratory pigment is largely present in 

 many Actinim. That it must be respiratory is shown by the 

 fact that one of its decomposition products is capable of 

 existing in a state of oxidation and reduction. That it is 

 closely related to haemoglobin is proved by the fact that it is 

 capable of being converted into hsemochromogen (reduced 

 hsEmatin) and hsematoporphyrin,* which are undistinguish- 

 able from the same products obtained from hsemoglobin. 

 (2) The respiratory pigment in the Actiniae cannot be looked ' 

 upon as a carrier of oxygen, but as a means to keep it in com- 

 bination until it is wanted by the cells for metabolic pur- 

 poses. " As it is' distributed all over the surface of some 

 Actinim, the whole body of such an animal may, in a physio- 

 logical as well as in a morphological sense, be considered 

 comparable to a single organ of a higher animal, so far, at 

 least, as internal] respiration is concerned." 



(3) In every species of Actinice, even in those almost 

 destitute of colour, the presence of respiratory pigments has 

 been detected. The coloured proteids, which are concerned 

 in tissue-respiration, enable the anemone to abstract oxygen 



* Moseley 's polyperythrin is identical with MacMunn's hsematoporphyrin. 

 t That is, tissue-respiration. 



