378 NaiuraUtHstorical Collections. 



on the gelatinous net-works, and again relented their course when they ha^ 

 passed through the openings. The motions were exactly such as we would 

 expect to be produced by cilia, disposed round the inside of the pores ; but the 

 most intense observation, with high magnifying powers, did not render cilia 

 visible on this or any other species which I examined. I now took deeper 

 sections from the substance of a great variety of living sponges, after remov- 

 ing their surface, and on examining them in the same manner, under a pow- 

 erful microscope, I found that, wherever a portion of an internal canal pre- 

 sented itself, there was a distinct and rapid current through it, but the moving 

 organs were as little distinguishable on these, as on the margins or net-works 

 of the pores. On looking with the microscope through the pores of a detached 

 portion of the S. compressa, I have sometimes observed a confused motion 

 among the granular bodies lining their sides, and have even seen these monade- 

 like bodies in groups staggering to and fro, when they had fallen separate to 

 the bottom of the watch glass. But, although every known analogy would 

 lead us to believe that these motions and the currents are produced by cilia, I 

 have never been able, by any artifice, or by the highest magnifjang powers, to 

 bring them distinctly into view in any species of sponge." — Edin. New Phil. 

 Joum. II. 126. 



We are inclined to believe, however, from the numeious analogies, that the 

 ciliated structure will, by deeper investigation, be found to be pretty universal 

 amongst aquatic invertebrata, and that it will probably also come to be classed 

 amongst those transient structures through which several reptiles and fishes pass 

 at an early period of their life. 



Upon the whole, it appears that the use of the cilia in producing currents in 

 the zoophytes, and in a few species of aealepha and gasteropodous moUusca, has 

 been already pretty clearly made out ; but the discovery of this wonderful pro- 

 cess, as a general property of the bivalve and gasteropodous moUusca, the anne- 

 lida, radiata, and, still more remarkably, of the tadpole and water salamander, 

 will stamp Dr. Sharpey as an highly ingenious and talented observer. And we 

 trust that he will pursue the investigation to its utmost limits. 



Additional references to Plate VII. 



Fig. 5. The Sertularia cuscuta of Ellis. 



a, a. The polypi, with their eight tentacula expanding beyond the denticle. 

 Fig. 6. Magnified representation of two of the tentacula, not from nature, but 

 for the purpose of showing the direction of the currents. 



On Calceolarice HybridcB ; by Dr. Grahaji, Professor of Botany in the 

 University of Edinburgh — It is with no slight feelings of disappointment that 

 have lately seen sent to the Botanic Garden some very fine hybrid varieties of 

 Calceolarice. The species lately introduced into cultivation in this country seem- 

 ed so well marked, and so entirely agreed with native specimens which have ac- 

 companied the seeds, that I did not fear a confusion of species in this genus ; 

 a confusion which in other genera seems to have rendered a distinction of species 

 impossible, and has given colour to the opinion that natural genera form the ulti- 

 mate divisions of plants with permanent characters. 



Mr. Morrison, gardener to Lord President Hope at Granton, being aware that 

 several of the finest species of Calceolaria were shy in producing seed, suspected 

 that this defect might be corrected, by applying the pollen of certain kinds to the 

 stigmata of others ; and he first has had the merit of presenting to the florist, 

 hybrids thus produced, which equal, if they do not surpass, in beauty, any of the 

 species of this handsome genus. Mr. Morrison's experiments have been confined 

 to four species, all herbaceous, viz. C. corymbosa, C. urachnoidea, C. plantagi- 

 nea, C. Fothergillii. He has succeeded in crossing the whole of these. C. plan- 

 taginea he finds most apt to produce seeds of itselfj and most readily to fertilize 

 others. The hybrids which Mr. Morrison has sent to the Botanic Garden are 

 the following : 



