iqo].] Records of the I ndian Museum. 6i 



faintly tinged with green; At a slightly later period the capsule 

 commences to bulge out at one pole, and finally forms a projec- 

 tion which may be either pointed or blunt at the free extrem- 

 ity, and is nearly as wide as, and several times as long as the 

 body to which it is attached. It is apparently hollow, and a 

 slight fold or constriction in its wall can generally be detected 

 a short distance from the proximal end. The coloured contents of 

 the capsule are still confined within their original limits, and as yet 

 show no sign of subdivision. The main part of the capsule next 

 increases in size and its contents split up, apparently by fragmenta- 

 tion, into numerous smaller bodies resembling the spore from which 

 the whole structure originated but rather less minute, a colourless 

 residue remaining. Some of these smaller bodies make their way 

 into the hollow projection, and the main part of the capsule gradually 

 becomes less distinct from the projection, which increases in girth ; 

 so that the whole structure assumes a pear-shaped or subspherical 

 outline. During this process the products of division divide and 

 become smaller by subdivision. Finall}^ the capsule ruptures and a 

 new generation of spores is set free. 



It is obvious that much further study would be necessary before 

 it would be possible to give a name to these violet bodies, and such 

 study would have little bearing, so far as it is possible to see, on the 

 subject of this paper. All that can be said is, that the}' appear to 

 represent an asexual cycle in the life-history of some minute alga. 

 It is of interest to note that if they are not phases of the same or- 

 ganism as the zooxanthellge , two s^^mbiotic, or at any rate inquiline, 

 organisms occur together in the inner tissues of the same Act- 

 inian. 



The position of the violet bodies in these tissues is practically the 

 same as that of the zooxanthellse, except that the former are inter- 

 not intracellular. They are not, however, sufficiently numerous in 

 the column to give a visible colour eft'ect, and even in the mesenteries, 

 in which they are far more numerous , they only colour the thin mem- 

 branous part. Stoliczka believed that the deep purple, often seen in 

 the region of the gonads, was directly due to the sexual products. So 

 far from this being the case, I find that when the ovaries are ripe or 

 nearly so, they lose their colour almost completely. The loss of 

 colour, however, is due not to the entire disappearance of the violet 

 bodies, but to the fact they are more widely separated from one 

 another as the eggs increase in bulk and so stretch the endoderm in 

 which the bodies are scattered. It is possible, however, that the 

 growth of the eggs has some direct effect on these bodies, which are 

 so scarce in the spent ovaries that the mesenteries have little colour 

 in this region after the eggs are set free. I have not seen an im- 

 mature individual with purple ovaries, and the violet bodies are 

 always absent from the acontia. 



From what has been said it is clear that neither form of Metri- 

 dmm schillerianum owes its coloration to pigment produced by its 

 own metabolism. In both forms the colours are due to independent 

 or semi-independent organisms, and the difference of distribution 



