66 SUMMARY OF CURRENT RESEARCHES RELATING TO 



formed, took the particles into, and then cast them out of its body. 

 Towards the evening of the day of observation the rosette-shaped 

 marking had totally disappeared, and its place was taken by a small 

 pit ; into this the sponge contracted the greater part of its body. 

 Chemical as well as mechanical agencies appeared to be at work, 

 but the demonstration of the presence of the acid was prevented by 

 the strong alkaline reaction of the sea water. Contrary to the view 

 of Hancock, Nassonow thinks that the spicules of the sponge take 

 no part in the boring operation ; indeed, the young sponge began 

 before it had developed any skeletal structures, not to say before 

 it had completely taken on the other characters of the adult. 



The second question deals with the influence of the parasitic mode 

 of life on the organization of the sponge ; of these results the most 

 striking is perhaps the fact that Clione appears to pass its eggs into 

 the water where, and not, as in all other sponges, in the body of the 

 animal, they become fertilized. 



Some information is given as to the structural characters of this 

 sponge, and the author states that the best sections were obtained 

 from specimens which had been treated with osmic acid, and 

 hardened in alcohol ; good results were also obtained by colouring 

 with hsematoxylin ; sections should, on account of the spicules, be 

 mounted in glycerine. On account of the closeness with which the 

 mesodermal cells are packed the sections must, as in Aplysina 

 (Schulze) be very thin. These closely-packed cell-layers fill, in 

 parts, the whole of the inner body-mass, and among them foreign 

 bodies — either food-remnants or calcareous particles — were not 

 unfrequently observed. Various forms of cells are to be noticed, 

 but between them all there are a large number of intermediate 



New Siliceous Sponges from the Congo.*— W. Marshall intro- 

 duces his description of these new sponges from fresh water by some 

 general observations on the relation of fluviatile to marine sponges. 

 Every one agrees that the former are genetically derived from the 

 latter, and most think that the origin was a monophyletic one. The 

 three general resemblances which lead to this view are : (1) they are 

 monactinellids ; (2) they inhabit fresh water ; (3) they exhibit an 

 asexual as well as a sexual method of reproduction. The first two 

 points appear to be of no importance, when we consider that three- 

 fourths of the marine SilicispongiBe appear to be monactinellid ; and 

 as against the third we have Dybowski's observation that there are no 

 gemmules in the Luhomirshia of Lake Baikal, and that a number of 

 marine forms reproduce by gemmation ; yet again, we must bear in 

 mind that gemmules are not confined to sponges, witness only the 

 analogous case of the Bryozoa. Gemmules, then, no more than 

 stinging cells, are to be used as criteria of genetic af&nities. A 

 careful discussion of all the facts of the case leads to the conclusion 

 that fresh-water sponges are most closely allied to the EenierinsB, 

 but that they have been developed independently of one another in 



* Jenaisch. Zeitschr. f. Med. u. Naturwiss., xvi. (1883) pp. 553-79 (1 pi.). 



