140 



HARD WICKE ' 5 .S CIE NCE- G O SSI P. 



Reproductive Organs, especially the Vestibule, in 

 Different Species of Uropoda." 



Photo-micrography. — I am obliged to Mr. 

 Roland Whiting for pointing out my mistake in 

 using the term "micro-photography" instead of 

 photo-micrography." Regarding the rigidity of the 

 apparatus, the fact that I can use it on board ship 

 and at sea will testify to that. — David Wilson 

 Barker. 



Cleaning Objectives in India. — Having used 

 the microscope for more than a dozen years in India, 

 and coming frequently in contact with other workers 

 with the instrument, I have a suggestion to make 

 which will, I trust, catch the eye of our leading 

 opticians. Books and catalogues recommend us to 

 send our objectives to their makers when they need 

 cleaning — advice which I have generally disregarded ! 

 It can be followed in England, but not out here. 

 Some objectives admit of being taken to pieces ; 

 others, unfortunately— and these of English make — do 

 not. I have to suggest that all objectives to be used 

 in India should be so put together as to enable their 

 possessors to take them to pieces readily, without 

 injuring the heads of small screws, &c. The expense, 

 delay and risk incidental to sending them to London 

 for such a simple matter, are distinct drawbacks to 

 their use. — W. J. Simmons. 



ZOOLOGY. 



Feeding Trout. — I shall be greatly obliged if any 

 of the readers of Science-Gossip can tell me of an 

 efficient, as well as cheap means of feeding the young 

 of trout when in the nursery. If any individuals or 

 natural food of the young of trout can be propagated 

 in the water of the nursery of this fish in sufficient 

 quantities as to be of any material use in the feeding 

 of them. — Clara Kingsford, 14, St. Dunstans Terrace, 

 Canterbury. 



Paludina Vivipara Var. Inflata, Loc.—l 

 do not quite understand the gist of Mr. Fryer's note 

 on p. 94 ante, wherein he makes reference to me, 

 and asks for a recognition on my part of his state- 

 ment with regard to P. vivipara var. inflata. His 

 note, it appears to me, is not pertinent, since what 

 records I made of North London shells were con- 

 cerning my own personal "takings," and did not 

 refer to "finds" made by any one else. What he 

 wishes me to admit seems no other than this : that 

 while he has found "forms" of P. vivipara in the 

 "Leg of Mutton" pond on the Heath, which he 

 personally considers referable to the var. inflata of 

 Locard, I have been unable to satisfy myself in that 

 respect with the various " forms " which have been 

 taken by me from the same locality. This I am 

 quite ready to admit, and I am as equally ready to 



admit that,^whether the forms belong to Locard's 

 inflata or not depends entirely on the "personal 

 equation" of the recorder. Other than this, the 

 question is one of a disinteresting nature. — J. W. 

 Williams. 



New Method of Preparing Lantern Slides. 

 —Dr. Sorby, F.R.S., recently gave a demonstration 

 of his new method of preparing specimens for ex- 

 hibition by the lantern. On the whole, his method 

 consists in drying specimens on glass, and in some cases 

 in subsequently mounting them in Canada balsam. 

 As an illustration, some cases may be described. 

 Taking such a beautiful Nudibranch as Eolis, it may 

 be first washed in a mixture of equal parts of alcohol 

 and water, then properly arranged on the glass, and 

 allowed to dry. Success depends to a great extent 

 on the fact that the edges dry first, and adhere to the 

 glass in such a manner that the subsequent drying 

 reduces only the thickness of the object ; and when 

 dry the original outline is perfect, and the animal 

 seems as if it were a projection on the plane of the 

 glass. When subsequently mounted in balsam and 

 used as a lantern slide, the natural form and colour 

 are seen on the screen like a beautiful picture. Such 

 Chretopoda as Niveis are easily prepared, and when 

 thrown on the screen, not only the general form but 

 every hair and the chief blood-vessels are visible, 

 though some of the latter are too small to be well 

 seen unless the real object is examined with a low 

 magnifying power as a hand specimen. Strange to 

 say, such very unpromising animals as Medusa give 

 most satisfactory results. They must first be de- 

 posited for a considerable time in diluted alcohol, to 

 remove the salt, then stained with Keinberg's hsema- 

 toxolin or Beale"s carmine, and finally dried on glass 

 and mounted in balsam. When thrown on the screen 

 the most important points in their structure are well 

 seen. The fringe of tentacles and the sub-umbrella 

 stain dark, whilst the canal system is beautifully 

 shown dark on a pale background. It would be 

 difficult to artificially paint a diagram showing the 

 structure better than does the real animal thus pre- 

 pared. Such preparations as those named above are 

 equally satisfactory as museum or cabinet specimens, 

 as they take up less room than bottles, do not lose 

 their colour, and can be easily examined in the hand 

 with low magnifying power. 



Spinning Habits of Cyclas Cornea. — In Dr. 

 Jeffrey's " British Conchology," p. 15, vol. i., there 

 appears an extract from a letter received from Dr. 

 Lukis, of Guernsey, referring to the habits of the 

 Sphrcriidre. In speaking of corneum as a thread- 

 spinner Dr. Lukis says, " Cyclas cornea is much less 

 active or inclined to ascend the glass ; in fact, I have 

 not seen it accomplish the feat." 1 have for some short 

 time kept a number of this species, and have found 

 it quite the reverse of the above one specimen, which 



