140 



HA RD WICKE'S SCIENCE- G OS SIP. 



" Journal of the Royal Microscopical 

 Society." — The April part contains, besides the 

 usual admirable summary of current researches in 

 every department of zoology, botany, &c, the full 

 address of the President (Dr. Dallinger), whose 

 partial publication in the " Times " and other 

 London newspapers, immediately after being de- 

 livered, excited much attention. This address is illus- 

 trated by plates of all the micro-organisms referred 

 to, and also by an admirable portrait of Dr. Dallinger 

 himself. 



Mounting in Balsam. — The query by Alfred 

 Pinnock (p. 113) is easily answered. From the 

 description of his method of working, it would appear 

 that when his object is fairly in the balsam, and the 

 cover-glass on, he puts a clip which presses out all 

 the balsam except a small portion, sufficient to fill 

 the space around the object between the cover-glass 

 and slide. The balsam pressed out soon begins to 

 harden, and this naturally prevents the evaporation of 

 the liquid or spirituous portion of the balsam, contained 

 under the cover-glass ; but as soon as he has removed 

 this the evaporation goes on more readily and rapidly 

 of the balsam included with the object ; this naturally 

 lessens its bulk ; and, as his clip has pressed the two 

 glasses as close together as the object will allow, it 

 naturally follows that less bulk requires less space, 

 and that gives room for the admission of air. The 

 cure will be to refrain from putting so much pressure 

 on the cover-glass, and the exercise of a little more 

 patience for the hardening process to be completed. 

 — C. Croydon. 



GUM-TRAGACANTH FOR INSECT MOUNTING. — Is 

 there any, and if any what, method of keeping gum- 

 tragacanth good, free from mould, and ready for 

 use, for any length of time ? When simply soaked 

 with water it usually gets mouldy in a few days. — V. 



ZOOLOGY. 



The Distribution of Mollusca in the Lake 

 OF Geneva. — A large species of Anodonta, common 

 in the lake, appears to obtain the assistance of small 

 fish in order to convey the "spat " to new grounds 

 in the following manner. When the tiny fish is at 

 hand, the germ of the mollusk is deposited actually 

 on the back of the fish in some manner ; it is thus 

 distributed in fresh parts of the lake, evidently be- 

 coming detached from the convenient locomotive. I 

 do not know if the fact is new to students of biology. 

 It was pointed out to the writer by the curator of 

 a Swiss museum. In a fresh-water aquarium the 

 Anodonta flourished vigorously ; in the same tank 

 the immature fish were darting about from weed to 

 weed, having bright silvery spots attached to the 

 back, somewhat like air-bubbles. These minute 



points, the curator informed me, develop into tiny 

 mollusks, and are suddenly thrown off the fish to the 

 gravelly bottom. — F. G. S. 



" The Rotifera, or Wheel-Animalcules." 

 — We have received the third part of this splendid 

 and useful monograph, in which the Melicertiadse 

 are continued, every genus and species being fully 

 described and figured. Chapter vii. is devoted to 

 the order Bdelloida, which includes the Philodinadse 

 and Adinetadae. Chapter viii. deals with the order 

 Plo'ima, containing the families Microcodidse, As- 

 planchnadre, and Synchoetadae. This third part 

 concludes the first volume of the work, for which 

 Dr. Hudson has written the Preface. It contains 

 fifteen plates, all in the highest style of art. 



Tengmalm's Owl. — A specimen of this rare 

 pigmy was killed in East Aberdeenshire a short 

 time ago. It was a female in good order (and is 

 now preserved), but weighed only 35 ounces. — W. 

 Sim, Fyvie. 



Provincial and other Societies. — The num- 

 ber of " Proceedings," " Transactions," &c, we are 

 constantly receiving from all parts of the British 

 dominions plainly indicate the widespread and rapid 

 progress of scientific study and inquiry. The " Pro- 

 ceedings of the Royal Society of Tasmania " for 

 1SS5 are especially rich in papers relating to the 

 geology, botany, and zoology of the island. Mr. 

 R. M. Johnston is a large contributor to the geology, 

 Mr. Baston to the botany, the Hon. W. Macleay to 

 the zoology. The present volume also contains a 

 sketch-map of the general geology of Tasmania, by 

 Messrs. C. P. Sprent and R. M. Johnston. We have 

 also received the "Transactions of the Hertfordshire 

 Natural History Society " for February and March, 

 1886, containing title page, etc., list of members, 

 proceedings for last year, report of the council, etc. 

 The sixteenth Annual Report of the Wellington 

 College Natural Science Society for 18S5 contains 

 accounts of the excursions, together with entomo- 

 logical, meteorological, and phenological . reports. 

 It also gives capital digests of the lectures delivered 

 before the members of the society. 



Chameleonic Arions. — Mr. Roberts's note on 

 page 118 deals with some extremely interesting 

 phenomena which have hitherto received but scant 

 attention. It is well known that the slugs have the 

 power of throwing out quantities of slime, which 

 covers their bodies, and experiment will readily show 

 that in some instances, when the slime is coloured, 

 they can by this means change their apparent colour 

 from grey to yellowish, or, as in the case of the 

 small A. ater found by Mr. Roberts, from white to 

 pale greenish. Mr. Roberts has sent me some of his 

 orange-yellow Avion hortensis, and it is perfectly 

 clear they derive their orange tint solely from the 

 colour of their slime, and if this is wiped off they 



