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HARDWICKE'S SCIENCE-GOSSIP. 



[April 1, 1SC9. 



MICROSCOPY. 



Pleurosigma hippocampus. — The habitat of 

 this diatom is " marine or brackish water." I have 

 never found it in fresh water, and am not aware of 

 any authority for its being so found. In Pritchard's 

 " Infusoria " it is described as marine ; in Smith's 

 " Synopsis " as of brackish water ; in Kutzing's 

 "Bacillarien" the locality given is the Baltic; 

 Rabenhorst (" Die Siisswasser Diatomaceen ") says 

 that it (Gyrosigma hippocampus) is properly marine, 

 but is found throughout Italy, Sicily, and the neigh- 

 bouring islands along the coast in shallow water 

 and brackish puddles [lialbsahigen pfiitzen) ; the 

 "Mi orographic Dictionary" says mariue or brackish 

 water. Will Mr. Kitton be good enough to say in 

 which of the British so-called fossil earths this 

 diatom may be found ? The inaccuracies (Science- 

 Gossip, 1867, p. 133) pointed out by your corre- 

 spondent Mr. Warner were noted by me at the time 

 in my copy of the Gossip; his corrections are 

 right except as to fig. 142. Pigs. 142 and 143 are 

 both representations, evidently copied from Smith's 

 " Synopsis," of Pin. stauroneiformis (S.), which I 

 have sometimes found to vary much both in outline 

 and absence or presence of central coste.— H. B. 

 If Mr. Warner refers to the "Synopsis" he will 

 find Pleurosigma hippocampus stated to be a brackish- 

 water form. Pritchard's book states it to be a 

 marine form, but refers to Rabenhorst's "Siisswasser 

 Diatomaceen." I have found it in gatherings from 

 Horning, Ormesby, Heigham — all fresh -water 

 localities. It is probably like Navicula amphisbecua, 

 and grows equally in fresh and brackish water. The 

 references to the figures are, of course, wrong. 

 Pimmlaria stauroneiformis = figs. 142 and 143 ; 

 Pinnuktria divergens = fig. 144; Pimmlaria acro- 

 asphari={\g. 141. It is a mistake to put much stress 

 on the habitats of diatoms. I have Terpsinoe musica 

 from barnacles scraped from a ship's bottom, and 

 also from a fresh-water stream in the Mauritius : in 

 both cases it grew luxuriantly. Cyclotella punctata 

 is found in very brackish water, and also in water 

 without a trace of salt; indeed, specimens I have 

 are from perfectly fresh water. Cyclotella Kutzingiana 

 is found under precisely the same conditions. See 

 Dr. Arnott's paper in the Microscopical Journal on 

 " What are Marine Diatoms?"— J. Kitton. 



Pine Pollen.— The common pine here is, I 

 believe, Finns pinaster, which produces a vast 

 amount of pollen, and which, with the flower scales, 

 are pretty objects; the outer scales covering the 

 flower are also interesting with low power. Some 

 years ago the south wind brought quantities of pine 

 pollen from the forests, and which was arrested by 

 the rain-water standing in pools in the streets, and 

 caused among many people no slight alarm, as they 

 imagined there had been a fall of sulphur, and 

 wondered what might crop up next.— G. S., Oporto. 



Anatomy op the Fly. — A treatise on the 

 Anatomy and Physiology of the Blow-fly, illustrated 

 with eight coloured plates, is announced by Mr. B. 

 T. Lowne ; and, from what we have seen of it, this 

 treatise promises to be an acquisition to micro- 

 scopical science. 



VoRTiCELLiE, or Bell Infusoria.— Among the 

 most common and yet most interesting of the In- 

 fusoria are the Vorticellse, or bell animalcules. 1 

 have examined a great number of specimens of the 

 Vorticella microstoma from the water in which 

 hyacinth bulbs have been growing. They consist. 

 of a bell-shaped body attached to a thread-like 

 muscular stalk, which anchors them to some con- 

 ferva or unicellular growth. On being alarmed, the 

 thread contracts into a spiral, and the ridges of the 

 bell close over the mouth in an instant, making 

 everything snug. A dark pith may be noticed run- 

 ning down the stalk. This Ehrenberg takes for a 

 muscular fibre, but M. Dujardin, who seems as a 

 natural consequence to combat Ehrenberg's views,, 

 supposes the outer layer to consist of contractile 

 tissue. The row of cilia inside the bell keep up 

 constantly a double whirlpool, causing two tides as 

 it were to flow into the mouth of the bell, bringing 

 the various spores or green granular matter always 

 present in the water into the mouth of the bell, 

 rejecting most of them again by what seems to be- 

 an anal aperture situated in the cell-wall above the 

 ridge of the bell. I again and again observed some 

 of these green granules slipped into the substance- 

 of the body, and gradually assimilated with it. This 

 is more easily observed on mixing a drop of water 

 coloured with carmine-lake, the granules being red, 

 and the stream out of the exit aperture coming out 

 like smoke from a chimney, discolouring the water 

 for a considerable distance. The manner in which 

 these animalcules multiply is very interesting. The 

 body, at first rather elongated, taking the oval in- 

 stead of the circular form, gradually the oval divides,, 

 and, taking the form of two circles pressed together, 

 these gradually separate, the bell opens, lateral cilia 

 appear on the sides of Vorticella;, and finally it 

 separates altogether and swims off to hang on its own 

 hook, or rather its own thread. I certainly observed 

 nothing in the way of an alimentary caual, and many 

 of the nuclei appeared to me to be nothing but the 

 granules present in the water, and taken in the 

 body as nourishment. I observed other nuclei of 

 more regular appearance brought out distinctly by 

 the carmine, and which separated at the division of 

 the body, and they seem probably to be nuclei or 

 germs of the separated animalcule. As this is the 

 season of the year when the Infusoria can be so 

 easily obtained, they should be examined by all able 

 to do so, and as much light as possible thrown upon 

 their somewhat obscure organizations.—//. Ashby, 

 Port low, co. Waterford. 



