576 0. A. MAC MUNN. 



an intrinsic Anthea pigment and another an algal pigment, 

 but simply this : that the colouring matters of the algse are 

 several, for we find at least one chlorophyll, one chlorofucin, and 

 certain lipochromes, and perhaps other pigments, all of which 

 belong to the " yellow cells/' 



The Physiological Proof is not wholly reliable. 

 The evolution of oxygen in the presence of sunlight in the 

 case of Anthea must to a large extent at least depend on 

 the situation of the " yellow cells," for it is evident that if in 

 a given species these are shut up in the tentacles the oxygen 

 given off has not much opportunity of escaping out of them so 

 as to make itself evident in a vessel containing the anemone, 

 moreover a large amount of the oxygen will in such a position 

 be largely absorbed by the tissues of the animal, and the same 

 manner in which the cells are packed, as shown in the accom- 

 panying drawing, prevents the deeper lying cells from being 

 acted upon by the rays of light. If on the other hand the 

 ectoderm of the animal were studded with algse there would 

 be a considerable development of oxyg en perceptible, and there 

 is certainly such a variation in the distribution of the " yellow 

 cells," for in some Actiniae I haveobserved rowsof algseembedded 

 in the ectoderm, while in others they may be mostly confined 

 to the tentacles. This point should not be lost sight of, and 

 may account for the discrepancy to a great extent. 



The Morphological Proof that the "yellow cells '^ are 

 parasitic algse has been so well discussed that I need not here 

 "treat of it," but I mayobservethatKrukenberg'sideaastotheir 

 hepatic function must, so far as their microscopic character is 

 concerned, be completely negatived. In no invertebrate liver or 

 answering organ are such bodies found. On the contrary, the 

 microscopic characters of liver chlorophyll or entero- chlorophyll 

 at once separate it from that of the ''yellow cells;" for, in the case 

 of entero-chlorophyll, it is easy enough to see that it occurs 

 mostly dissolved in oil, or in granules, or diffused through the 

 protoplasm of the lining cells of the liver tubes.^ The spectro- 

 scopic reasons for the same conclusion are considered below. 



1 ' Proc. Roy. Soc.,' No. 237, 1885, aud ' Pliilos. Trans.,' 1886, Part I. 



