2i8 PHYSIOLOGY OF THE INVERTEBRATA. 



(j) Corwjvadis riridis. — MacMnnn has examined the red 

 specimens of this little sea anemone. On putting one of 

 these animals into a compressorinm 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 actiniohtematin or actiniochrome, for 

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

 they belong to a pigment which is related to actiniohasmatin, 

 for this pigment can readily be changed into ha3mo- 

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

 or green varieties of ('. TtridiH. There is no doul)t that this 

 anemone contains a respiratory pigment allied to actinio- 

 hajmatin. 



The important researches of MacMunn and others have 

 shown: (i) That a ra^inratory pigment is largely present in 

 many Adinia\ 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 

 hamatin) and hjematoporphyrin,* which are undistinguish- 

 able from the same products obtained from ha?moglobin. 

 (2) The respiratory pigment in the Actinice cannot be looked 

 upon as a t-orr-in- of oxygen, but as a means to Irq) 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 

 Actinia:, 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 Actinia:, 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 pclyperythrin is identical with MacMunn's haematoporphyriu. 

 t That is, tisiue-respiration. 



