go 



SCIENCE- G OS SIP. 



r arious 



cell is a dry one, and the cover-glass is held in 

 place only by the paper covering the slide. The 

 cell would therefore not be hermetically sealed. 

 The mite referred to may be TyrogVyphus ento- 

 mqphagits or Cheyletus eruditus, the book-mite, 

 both of which are not uncommon unfortunately in 

 museums and collections, where they feed upon 

 the specimens, causing much havoc. Cheyletus 

 can be distinguished by its large raptorial palpi, 

 of which a good drawing appeared in Mr. Allen's 

 •• Journal of Microscopy,'' 1893, p. 100. There is a 

 drawing in the " Micrographic Dictionary," but it 

 is not accurate. — Ed. Microscopy, S.-G.] 



EXTEACTS FROM POSTAL MICROSCOPICAL 

 SOCIETY'S NOTEBOOKS. 



[Beyond necessary editorial revision these ex 

 tracts are printed as written by the vari 

 members. — Ed. Microscopy, S.-G.] 



Parasite op Gold-Fish. — This is a most vora- 

 cious little creature. As often as I removed him 

 from his host he swam directly back again, and it 

 was only with great difficulty he could be dislodged. 

 The chief place of attack seemed to be about the 

 shoulders. At the time I caught this parasite 1 

 was very much engaged, so sent it to a pro- 

 fessional mounter in London to be mounted, asking 

 at the same time for any information he could 

 give me on the creature. He said he had had 

 similar ones from the Brighton Aquarium, but 

 could not tell me anything more. It is a singular 

 creature, possessed of numerous ciliated swim- 

 merets ; but perhaps its chief feature of interest is 

 the means by which it fastened itself to its host. 

 These will be seen at the anterior end in the shape 

 of two very powerful suckers, around which there 

 seem to be a large number of radiating ciliary 

 muscles. There are also two singular organs of a 

 triangular shape not far from the suckers, appa- 

 rently of a chitinous substance. I should be glad 

 of information on this parasite. — R- T. DUcltfield. 



Q^ten 



Fig. 2. Terminology of Argulus. 



This parasite is Argulus foliaceus. The follow- 

 ing description is from the " Micrographic Dic- 

 tionary": "A genus of Crustacea, of the order 

 Siphonostoma and family Argulidae. Characters : 

 Carapace membranous, covering the cephalo-thorax 

 like a shield ; antennae four, short, concealed 

 beneath the carapace, anterior two-jointed, term- 

 inal joint hooked ; posterior four-jointed; rostrum 

 acuminate ; five pairs of legs, the place of the 



first (6th) pair being occupied by two suckers ; 

 second pair short, five-jointed, the two basal joints 

 spinous, the last joint with two small hooks ; the 

 last four pairs of legs two-cleft, and furnished with 

 ciliated filiform processes." The Argulus is usually 

 found parasitic on fresh-water fish, and is often 

 called "fish-louse." — C. Folltard 



This is certainly Argulvs foliaceus. It is a very 

 old friend of mine. I took a careful drawing of 

 one some time ago. I have fallen across this- 

 parasite several times since. Science-Gossip gave 

 a figure of one some years ago, which was after- 

 wards reprinted in Taylor's " Half -horns in the 

 Green Lanes."' It is found on all kinds of fresh- 

 water fish, and Taylor says it is also found on the 

 tadpole. — Chas. D. Soar. 



[The drawing reproduced herewdth is from a 

 sketch by Dr. J. R. L. Dixon, of Bournemouth, a 

 member of the P.M.S., and is apparently taken 

 from the " Micrographic Dictionary." There is 

 an illustrated article on "Fish-lice," by Mr. F. 

 Noad Clark, at p. 324, S.-G.,Yol. V., N.S., describing 

 the life-history of Argulus. — Ed. Microscopy, S.-G.} 



Mounting Rotifers and Hydrozoa. — I have 

 never seen any successful mounts of rotifers. Can 

 anyone instruct me how to do it 1 Fresh water is 

 full of beautiful creatures, but we seldom see them 

 preserved as slides. My method of mounting- 

 rotifers has been to drop one per cent, solution of 

 osmic acid on the slide, and close the cell. — William. 

 H. Burbidge. 



Mr. Burbidge's failure is fully explained by his 

 having killed the rotifers too quickly. They 

 require narcotising first and then killing at the 

 right moment. This is Mr. Rousselet's method, as 

 fully explained in the " Journal of the Quekett 

 Club" for 1893, p. 205. I understand that this 

 method has not been tried on polyzoa, but I think 

 it is worth trying. — J. S. Pratt. 



I have tried osmic acid with the fresh-water 

 hydra, but only about one in a dozen is passable. — - 

 J. Phillips. 



I have mounted hydrozoa with fully expanded 

 tentacles quite successfully by the following 

 method : Place them in a rather shallow vessel of 

 sea-water and add, very gently, a few drops of 

 chloroform-water by means of a pipette. At first 

 the hydra will draw in their tentacles, but if not 

 too much has been given they will expand 

 them again. Then add a little more chloroform- 

 water. After a while, under the influence of the 

 anaesthetic, the animals will become apparently 

 stupefied and cease to draw in their tentacles. 

 Now is the time to kill them, and this is done by 

 suddenly pouring over them a hot saturated solution 

 of corrosive sublimate. This method does also for 

 rotifers. They should be mounted, not in glycerine, 

 but in balsam or weak corrosive sublimate solution. — 

 A. Montague. 



I once spent some time trying to mount rotifers, 

 but with very little success. It is useless trying to 

 fix them instantly with osmic acid. They require 

 to be previously narcotised. The difficulty is to 

 know when they are sufficiently narcotised for the 

 application of the fixing agent. — /. II. L. Dixon. 



[We have already described Mr. Eousselefs method 

 of preserving and mounting rotifers (see SciENCE- 

 Gossip, Vol. VII., page 88). A fuller and more de- 

 tailed account is contributed by him to Cross & 

 Cole's "Modern Microscopy," as well as to various 

 publications of microscopical societies. — Ed. Micro- 

 scopy, S.-G.] 



