208 Mr. H. J. Carter on the Position of the 



I cannot say that microscopic slices of stained sponges, 

 reduced to extreme thinness by the microtome and mounted 

 in balsam, that is under compression, are to me so satisfactory 

 as thicker slices simply stained and mounted in glycerine with- 

 out compression, since in the latter the ampuUaceous sacs may 

 be seen in an unmolested state unaltered by any compression 

 or microtomizing, that is entire and in situ. However, there 

 is no objecting to what Schulze has illustrated any further 

 than that it does not seem to me to convey such a general 

 conception of an ampuUaceous sac and its position in relation 

 to the water-canal as that which I have seen under the circum- 

 stances above mentioned — that is, a globular water-vessel 

 with no neck imbedded in the confines of a water-canal with 

 the mouth opening upon the surface of that canal. 



In the syconoid cylindrical chamber of the calcareous sponge 

 Teichonella lahyrintMca^ which, as I have already stated, is 

 homologous with the ampuUaceous sac, there are not only 

 two main openings, that is, pores at one end and a large single 

 vent at the other, but the interior of the chamber is covered 

 with spongozoa intermingled with a great number of other 

 pores or smaller holes ('Annals,' 1885, vol. xv. p. 119, pi. iv. 

 fig. 7 &c.), so that, in fact, it is so far ])recisely like that 

 which Schulze has described and illustrated in the siliceous 

 sponges. And this structure is continued on to Leuconia 

 nivea and Teichonella prolifera^ although the chambers arc 

 here so divided up as to resemble both in size and position the 

 ampuUaceous sac, which, together with the now tree-like 

 form of the water canal-system opening as vents and pores 

 respectively on the surface (as there is no cloaca in these 

 species), renders the whole almost identical with that of the 

 siliceous sponge. 



I have stated that " there is no cloaca " in Leuconia nivea 

 and Teichonella prollfera ; but the fact is that the termination 

 of the large canal of the water-systems respectively in all 

 sponges is but a modified cloaca, and therefore those of Leu- 

 conia iiivea a.Y\(\. Teichunella proliyera must he considered the 

 same ; but for distinction sake it is necessary to separate them 

 from those Calcispongiai which possess that particular kind 

 of ending of the excretory canal-systems which has been dis- 

 tinguished by the name of " cloaca/' of which many similar 

 instances exist in the adult forms of the siliceous sponges. 



This, however, does not interfere with the fact that the 

 admission of water for respiratory purposes, while it also 

 carries in with it the elements of nutrition, is effected through 

 the pores or inhalant orifices of the surface, while the dis- 

 charge takes place at the vent or exhalant orifice at the other 

 end of the cylindrical chamber. 



