182 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



2 of Alcyonium (1 new). There are some interesting notes on 

 geographical distribution, and on the structure of the forms described, 

 e.g. as to cnidoblasts, zoochlorellse, gonads, and canals. 



Maturation of Ovum in Alcyonium digitatum.* — M. D. Hill has 

 reached some remarkable conclusions which, if true, separate the matura- 

 tion processes in the egg of Alcyonium from all hitherto described cases. 

 No polar bodies are formed in the ordinary sense. The division of the 

 female pronucleus before the entrance of the spermatozoon is irregular 

 and amitotic. No chromatin leaves the egg in the stage of ovocyte I., 

 to use Boveri's nomenclature. The female pronucleus completely 

 disappears. There are no bodies that can be termed chromosomes 

 throughout the whole process. The first segmentation nucleus is derived 

 from the male pronucleus, but it is quite possible that chromatin equal 

 in amount to that of the male may also be derived from the female pro- 

 nucleus, though all trace of the latter has been lost. 



Lime-forming Layer of the Madreporarian Polyp, t — Maria M. 

 Ogilvie Gordon refers to Duerden's work on Siderastrea, and emphasises 

 the general fact that the ectoderm does not directly separate out 

 calcareous matter, but organic matter, within which the crystals develop. 

 On Professor Duerden's interpretation, we are to believe that the 

 exceedingly particulate skeleton arises by a sort of crystallisation in an 

 organic cuticular matrix produced by, but distinct from, the ectoderm. 

 Mrs. Ogilvie Gordon upholds her opinion, supported by remarkable 

 correspondences of measurements, which cannot be mere coincidences, 

 that the individual ectoderm cells or nuclear parts exert a determining 

 individual influence on the origin of the lime-forming skeletal units 

 ( = " calicoblasts " in her work) in the cuticular product, which is, after 

 all, a composite product from many ectodermal cells, and persists in 

 retaining its originally particulate character. 



Ciliary Currents in Actiniaria and Madreporaria.J — Oskar Carl- 

 gren has made a precise study of the varied distribution of cilia and the 

 various currents in these forms. He discusses the functions of the cilia, 

 especially in wafting food-particles inwards, and in wafting useless 

 material outwards, and shows that there are four distinct types. 



Victorian Graptolites. § — T. S. Hall gives an account of Upper 

 Ordovician Graptolites from the neighbourhood of Mount Wellington. 

 Eight different species are described, several of which are new. 



New Species of Hydra.|| — N. Annandale describes from the Calcutta 

 tanks a hydra which he is inclined provisionally to class as E. orientalis 

 sp. n. The tentacles and base are milky white, the distal portion of the 

 body is either pale or dark olive-green, deep chestnut, orange-brown, 

 pale -brown, cream colour, or dirty white, never bright green. Every 

 phase of colour may be found in the same tank, but the darker specimens 



* Quart. Journ. Micr. Sci., xlix. (1905) pp. 493-505 (7 figs.). 



+ Tom. eit., pp. 203-11. 



t Biol. Centralbl., xxv. (1905) pp. 308-22 (6 figs.). 



§ Proc. Roy. Soc. Victoria, xviii.,n.s. (1905) pp. 20-4 (1 pi.). 



|| Journ. and Proc. Asiatic Soc. Bengal, i. (1905) pp. 72-3. 



