ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 413 



of a discovery of a nervous system in sponges ; we drew attention to his 

 apparent ignorance of a demonstration made at a meeting of the Society 

 by Prof. C. Stewart. Prof. Stewart's discovery was published, with an 

 illustrative figure, on p. 431 of Prof. Bell's ' Comparative Anatomy and 

 Physiology ' * (1885). This figure showed Dr. v. Lendenfeld that 

 Stewart's sensory cells were different from those described by bimself, 

 and by the kindness of the latter he has been enabled to examine the 

 original specimens. 



He describes very long and large conical processes as arising every- 

 where on the surface of the sponge, and as having a widened basal piece ; 

 they are almost 0*1 mm. long, and about 0-016 mm. broad at their 

 base; they are especially numerous at the entrance to the interradial 

 currents. As neither F, E. Schulze nor Hackel have observed thete 

 structures in living Sycandrae, and as Dr. v. Lendenfeld has never seen 

 them, he suggests that they are ordinarily retracted, and are only to be 

 found extended under specially favourable conditions. 



The processes consist of a substance which is identical with mesoder- 

 mal intercellular substance, and are, apparently, invested by tubular 

 epithelium ; just below the broadened base there are several oval nuclei, 

 surrounded by somewhat irregular plasmatic investments, and continued 

 as a fine filament^ to the tip of the conical " palpocil " ; Stewart's figure 

 shows only one cell in each palpocil. If the process be withdrawn we 

 get a group of cells very similar to the pyriform sensory cells already 

 figured by von Lendenfeld. 



The author concludes that in certain sponges there are special sensory 

 organs which cannot be compared with what are found in Coelenterates or 

 Coelomata; they may be called synocils in opposition to the simj)le 

 palpocils. They probably represent a higher grade of development of the 

 ordinary palpocil with its proper sensory cell, and perhaps owe their 

 origin to the fusion of several simple palpocils, and the surrounding of 

 the group with a proportionately well-developed layer of mesodermal 

 intercellular substance ; they are of mesodermal and not endodermal 

 origin. The pyriform cells, which unite to form the synocil, are homo- 

 logous and analogous with the spindle-shaped sensory cells of other sponges. 



Position of the Ampullaceous Sac and Function of the Water-canal- 

 system in Spongida.t — Mr. H. J. Carter endeavours to show that the 

 pores in a sponge are as much for the general circulation and respiratory 

 function as for the introduction of nutriment, and that the ampuUaceous 

 sac [or flagellated chamber], being situated on the surface of the excretory 

 canals, only requires a single aperture to fulfil its function. He finds 

 new evidence to support this view in a new species of South Australian 

 sponge, which he calls Wilsonella echinonematissima. At the same time 

 he does not doubt that in many instances there is more than one aperture 

 in the sacs, but states that there is probably an equal number in which 

 there is only one that serves the two purposes of inception of nutrient 

 particles and exit of unassimilated material. The new species of sponge 

 is remarkable as having the body-fibre of the Echinonematous type, and 

 the terminal part that of a Psammonematous sponge ; the sacs are sharply 

 defined, persistent, comparatively scanty, and unusually tough under 

 manipulation, so as to render the species excellent for observations on 

 these structures. 



* "Which Dr. v. Lendenfeld quotes as ' Bell's Text-book of Zoology,' London, 188G, 

 p. 144. 



t Ann. and Mag. Nat. Hist., xix. (1887) pp. 203-12. 



