856 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(without solid calcareous or horny axes) examined, e. g. Cvelogorgia, 

 Briareus, NepJitliya, Spongodes, Tuhipora, Clavidaria, Heliopora, &c. 



Amongst the dimorphic Alcyonarians the sij)honoglyphe is usu:illy 

 absent in the autozooids, but well develojied in the siphonozooids. 

 In Sarcopliyton, however, a feebly developed siphonoglyphe is present 

 in the autozooids in addition to the well-developed ones in the 

 siphonozooids. 



In Primnoa and Villogorgia, the only examples of Alcyonarians with 

 solid axes examined, no siphonoglyphe can be found, and the author 

 is inclined to think, from the researches of other observers, and from 

 general considerations, that it is not present in any genera in which 

 the fleshy parts of the colony are represented only by a thin crust 

 covering solid axes. 



The paper contains some speculations to which the author has been 

 led by these researches, concerning the probable philogeny of the 

 grouj), and a diagrammatic arrangement of the Alcyonaria on these 

 lines. 



Finally, he proposes to divide the Alcyonaria into five principal 

 groujjs : 1st. The Proto-Alcyonaria, including only those genera which 

 do not form colonies. 2nd. The Stolonifera, including the genera Clavu- 

 laria, Cornularia, Tnhijyora, &c., in which the young colonies sj^ring 

 from a creeping stolon. 3rd. The Pennatulidte, which remains as here- 

 tofore. 4th. The Gorgonidfe, a grouj) which contains only those genera 

 in which there are solid horny or calcareous axes, and no siphono- 

 glyphe. 5th. The Alcyonidffi, a large and somewhat heterogeneous 

 grouj) containing all the remaining genera of the Alcyonaria, which, 

 though exhibiting many wide variations, infer se, agree in possessing 

 no specially marked characters of deviation from an ideal central 

 form from which it is suj)posed they must have sprung. 



Porifera. 



Vital Manifestations of the Sponges.* — Taking the sponges as 

 an example of a group in which tissues, organs, and j)hysiological 

 divisions of labour are almost entirely absent, B. Solger makes them 

 the starting-point in his proposed study of vital manifestations and 

 their increasing complication in the animal kingdom. He gives a 

 summary of facts deduced from observations by various writers. 



The functions of the endodermal ciliated chambers and cells appear 

 to be respiration and the prehension of nutriment, recent researches 

 seeming to deny them the — at any rate exclusive— power of actual 

 digestion. The mesoderm probably shares in the latter function : 

 the claim of the ectoderm to this position is less indisputable. The 

 occasional occurrence of lipostomy and lipogastry does not affect this 

 question much, but relates chiefly to the manner of disposing of the 

 used-up water ; the function of exhalation is transferred in lipostomy 

 to other canals and pores, that of digestion in lipogastry is taken up 

 by the ciliated chambers or possibly by the ectoderm and mesoderm. 

 The discovery of digestive ferments (pepsin, trypsin) in the body of 



* Biol. Ceutralbl., iii. (1883) pp. 227-35. 



