584 SUMMARY OF CURRENT RESEARCHES RELATING TO 



process of migration through the tissues, a phenomenon similar to that 

 recently described by Hadzi in hydroids. The main thread-cell batteries 

 in Mcerisia are those around the oral opening and those on the four 

 perradial tentacles. The thread-cells of the oral battery develop in the 

 more proximal parts of the manubrium, and make their way through the 

 endoderm and structureless lamella to the ectoderm of the mouth-region, 

 the movements being effected by the amoeboid cnidoblasts. The neniato- 

 cysts of the perradial tentacles probably develop in the large ocellar bulbs 

 at the bases of the tentacles. 



Gonadial Grooves of Aurelia aurita.* — T. Goodey discusses four 

 narrow canals, lying in the inter-radial axes, on the ventral walls of the 

 main passages from the central gastric cavity to the gastric pouches, and 

 on the floors of the gastric pouches themselves. They terminate in 

 slightly funnel-shaped expansions at about the centre of each pouch. 

 The boundaries of each groove are formed by two parallel ridges of 

 epithelium, which are raised up so as to form a channel between them. 



From observations of numerous specimens the author has convinced 

 himself that these gonadial grooves function as gonoducts, and that it is 

 only within their limits that the sex-cells pass on their way to the exterior. 

 Thus Aurelia may be looked upon as possessing ccelomic or archenteric 

 derivatives of the nature of primitive gonoducts. 



Indian Ocean Stylasterina.f — Sydney J. Hickson and Helen M. 

 England report on a collection made by Stanley Gardiner, including 

 Distichopora profunda sp. n., Sporadopora providential sp. n., and Conopora 

 dura sp. n. In regard to Distichopora violacea Pallas, it is concluded 

 that the species is protandrous, and that the purple colour is the last of 

 a series of colour-changes in growth. 



Budding of Hydra 4 — Jovan Hadzi finds that the bud of a Hydra 

 does not arise simply as an evagination of the two layers of the parent 

 animal. Things are seldom so simple as they at first sight appear. 



What, then, is a bud ? It arises by local " activation " of the 

 indifferent or interstitial cells below the ectoderm. This is shown by 

 the fact that the beginning of bud-formation is the intense multiplication 

 of the indifferent cells. This is the first step. 



The second step is this, that the indifferent cells insinuate them- 

 selves between the ectodermic epithelial cells and become like them, and 

 that they likewise pass through the supporting lamella and become 

 nutritive-muscular cells. This seems to go on throughout the polyp's 

 life. A bud may be due to the two layers as such, or to indifferent 

 (mesenchymatous) cells. 



Selaginopsis.§ — James Ritchie proposes to add Selaginopsis mirabilis 

 Verrill to the British list. Specimens were found in the net of a trawl- 

 boat which had taken its last few hauls off Flamborough Head. They 

 were quite fresh, with the perisarc in good condition, and were growing 



* Proc. Zool. Soc, 1909, pp. 78-81 (1 pi.). 

 t Trans. Linn. Soc. London (Zool.) xii. (1909) pp. 345-54 (1 pi.). 

 X Arbeit. Zool. Inst. Univ. Wien.xviii. (1909) pp. 61-82 (2 pis.). 

 § Proc. Roy. Phys. Soc. Edinburgh, xvii. (1909) pp. 217-22 (3 figs.). 



