240 Notes and Memoranda. 



New Freshwater Polyzoa. — Mr. C. Parfitt describes, in Annals Nat. Hist., 

 two new freshwater polyzoa he found in Devonshire, Plumatella lineata and 

 Limnas. The first is characterized by eight or ten dark brown longitudinal lines 

 running the whole length of the tubes. The polyp cells are barrel-shaped, and 

 hyaline, the mouth entire, each having five or six dark brown annulations, slightly 

 constricted at each annulus. Tentacles sixty-two ; statoblasts dark reddish 

 brown, elliptical, with a broad yellow margin. It was found on the underside of 

 water-lily leaves, in a pond in Mr. Veitch's old nursery, Topsham Road, Exeter. 

 The other (P. limnas) belongs to that section of the genus which includes P. 

 emarginata ; " but the line of demarcation between the diaphanous portion of the 

 tube in this species and the thick opaque walls of the inferior half, gives it even 

 at first sight a very distinct and marked appearance. Another striking peculiarity 

 is that the tubes grow mostly in pairs, and are very closely adherent to the 

 matrix, except the polyp cell, which stands up conspicuously near the end of the 

 tube." The lower half of the tubes are opaque, and coated with grains of 

 reddish-brown matter. The opaque walls are white inside, and made up of pen- 

 tagonal cells. Tentacula fifty to fifty-four ; calyx festooned. " Statoblasts ellip- 

 tical, yellow, with a narrow blackish ring dividing the cell from the narrow purple 

 rim or annulus which surrounds it." The orifices are conical, not quite at the 

 end of the tubes, and stand at right angles to the tubes, being raised by three or 

 four folds or rings. 



Silvered Object- Glasses eor Sun- Viewing-. — M. Foucault proposes that, 

 for the special purpose of viewing the sun, large achromatic objectives should 

 have their outer sides silvered by chemical precipitation. He finds that a silver 

 film, such as that deposited on the silvered mirrors for telescopes, does not inter- 

 fere with the definition of an object, like the sun, bright enough to be seen 

 through it. 



The Spontaneous G-enebation Controversy still occupies the French 

 Academy. Recently, M. Al. Donne, who formerly took the opposing side, 

 adduced experiments on the affirmative side. He punctured the shells of eggs 

 with a red-hot wire, enveloped the eggs in cotton that had been heated, with a 

 view to destroy germs, and then immersed them in hot ashes. In the course of 

 three weeks or a month he found moulds growing on the organic matter of the 

 egg. M. Pasteur pointed out that the precautions to exclude germs of small 

 organisms were by no means sufficient, and hence the experiment must be rejected. 



The Cholera Mist. — Should the blue mist described by Mr. G-laisher still 

 appear in any part of the country, it is most desirable that the organic particles 

 it may contain should be accurately examined by the aid of the microscope. Mr. 

 Grlaisher and other observers have detected some small bodies of a blue colour, 

 the nature of which has not, we believe, been thoroughly investigated. Micro- 

 scopists should endeavour to ascertain whether such particles exist in sufficient 

 quantities to account for the colour, and whether they represent known forms of 

 sporules. 



An Apple Congress. — The French Pomological Congress began its eleventh 

 session at Melun on the 14th September. Its object is to induce the rejection 

 of all mediocre and bad sorts of apple-trees, and to promote the cultivation of 

 the finer and more profitable kinds. It is expected that the export of French 

 apples will be extended by these measures ; and we have need, as Mr. Roach 

 Smith has pointed out, of something of the sort in this country, where the 

 supply of good apples is below the wants of the population. 



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