7. Anthozoa (incl. Hydrocorallia). B. Alcyonaria. 23 



cells and sense cells have been isolated, the former are fusiform, the latter 

 are slender and their hair-like distal ends project beyond the ectoderm, their 

 inner ends being prolonged into branching processes. The sense cells appear 

 to be in very intimate connection with the nematocyst-cells and they innervate 

 the latter. 



Pratt removes from Lobopkytum to a new genus [Sclerophytum] those species 

 which have minute (or no) siphonozooids and a large superficial canal system. 

 In Scl. there are both longitudinal and superficial canal systems but the latter 

 is not found in Lob. and Sarcophytum. In Sarc. the principal longitudinal 

 vessels are direct prolongations of the siphonozooids but in Scl. these zooids 

 terminate in the large vessels of the superficial canal system. In addition 

 to these canals there are, in all 3 genera, short straight ciliated canals con- 

 necting neighbouring autozooids. In Scl. the siphonozooids are small, in some 

 species they are degenerate (short vertical coeca, not open to the exterior, from 

 the superficial transverse canals) and in 2 species they are absent. By intro- 

 ducing lamp-black into the sea water about living colonies of Sarc., J. S. Gar- 

 diner observed the currents entering the siphonozooids. After some time the 

 blackened water was ejected by the autozooids, and in some cases by the 

 siphonozooids , showing that there had been a reversal of the current within 

 the colony. Growth of the colony by formation of new autozooids is most 

 vigorous on the margin in Sarc. hence the mushroom shape is retained; colo- 

 nies of Lob. and Scl. soon lose this shape as growth takes place from any 

 part of the capitular surface which becomes lobei. The autozooids of Scl. 

 are smaller than those of Sarc. and Lob. Their lateral and ventral mesen- 

 terial filaments are more feebly developed, this is perhaps correlated with the 

 presence of numerous zoochlorelhc as these are most abundant in Scl. gardi- 

 neri which has no lateral or ventral filaments. In this respect, in the presence 

 of more than one row of pinnules on the tentacles and of a superficial canal 

 system and in its less marked dimorphism Scl. approaches Xenia. - The author 

 describes Sarcophytum 6 (2 n.), Lobophytum 1, Sclerophytwni 8 (6 n.) and Al- 

 eyonium 1. 



Wilson gives an account of the development of fragments of eggs and pla- 

 nuke and of experiments on regeneration in young colonies of Kenilla. The 

 cleavage nucleus divides 3 to 5 times before cleavage of the cytoplasm occurs 

 and the egg usually segments at once into 8-16 blastomeres 2 or 3 hours 

 after it is laid. 24 eggs were cut into 2 to 5 pieces which were isolated in 

 sea water containing spermatozoa. One piece from each of the first 19 eggs 

 developed. These fragments divided like whole eggs and at the same time 

 with the latter (2 i / z hours) into approximately 8 or 16 blastomeres. In the 

 5 other cases 2 or 3 pieces from each egg developed, segmenting so that the 

 total number of blastomeres formed from the pieces of each egg was the same 

 as that produced from an entire egg. Development of only a single fragment 

 in the first 19 cases is due to the fact that the egg still contains a single 

 nucleus, in the other cases the nucleus had divided and more than one nucleated 

 piece was obtained from a single egg. The period at which cleavage occurs 

 does not depend on the number of nuclei in the piece but on some other pro- 

 gressive change which reaches the critical point at the same time whether the 

 egg be entire or cut into pieces. After fertilisation has occurred, despite the 

 absence of a fertilisation membrane, non-nucleated pieces of the egg cannot 

 be again fertilised. An egg-fragment not more than ' / 4 the volume of an egg 

 may develop into a dwarf-larva, which, after swimming for the normal period 

 (48 hrs.), sinks to the bottom, forms tentacles and the first pair of buds in 



