Feb. 1, 1SC7.] 



HARDWICKE'S SCIENCE-GOSSIP. 



35 



by lir, then another piece -J- inch narrower, the extra 

 size of the first being required as a ledge, on which 

 to drop the water or rest the object previously to 

 inserting it between the glasses. Now prepare a 

 piece of cardboard or cartridge-paper, half an inch 

 less in width than the length of the bath ; this is to 

 be placed between the two glasses, and withdrawn 

 after the bath is complete. Upon its thickness 

 depends the depth of the water between the glasses; 

 and, therefore, if a high power is to be employed, 

 cartridge is better than cardboard. 



Fig. 30. Cell used in the observation of Melicerta with 

 high powers. 



When all is "prepared, and the wax melted, the 

 edges of the glasses which project beyond the card- 

 board are to be dipped into the wax, which soon 

 forms a union between them ; and in a few minutes 

 the card may be withdrawn, and the bath is ready 

 for use. It should then be filled with water by a 

 dipper, and a specimen selected for insertion. 

 Before doing this, it is advisable to remove as much 

 of the weed as possible, so that the piece which is 

 left may be flat, or it will not pass between the 

 glasses. This is effected by first resting it on the 

 projecting ledge, and then moving it gently forward 

 with a needle or any thin object, till it is fairly 

 positioned for observation. The water evaporates 

 slowly, and must be renewed occasionally with the 

 dipper. The peculiar advantage of this bath in the 

 case of Melicerta consists in the free supply of 

 water, as without this these delicate creatures will 

 close or work so fitfully that sustained observations 

 are impossible. It would also be found highly 

 valuable for Zoophytes, or any creatures of a 

 similar character. XL E. Gheen. 



[The above is an abstract of a paper read at the 

 Quekett Microscopical Club.] 



Pliny tells us that Cato of Utica was one time 

 reproached for selling poison, because when dis- 

 posing of a royal property by auction he sold a quan- 

 tity of Cantharides at the price of 60,000 sesterces. 





RHIZOSOLENIA. 



A CURIOUS genus of Diatoms was introduced 

 -^*- to notice by Mr. Brightwell in the sixth 

 volume of the Microscopical Journal. This was 

 called Rhizosolcnia, and with a view to its better 

 acquaintance, we have given figures of two species, 

 and a brief summary of the rest. 



Five British species are on record, and besides 

 the singularity of their forms, they are remarkable 

 for being only found in the 

 interior of marine animals, 

 chiefly Ascidians. Rhizo- 

 solenia styliformis is figured 

 to the left hand (fig. 31), 

 that on the right being 

 Rhizosolenia im bricata 



(fig. 2), so named from the 

 imbricated appearance of 

 the valve. Rhizosolenia 

 setigera has a terminal 

 bristle, sometimes nearly as 

 long as the frustule. Rhizo- 

 solenia alata is a curious 

 little species, with a short 

 bristle seated at the base 

 of the hood-like cap which 

 ends the frustule. And 

 Rhizosolenia robusta is more 

 anomalous in its form, being 

 broad, somewhat sigmoid, 

 and terminating at each ex- 

 tremity in a short bristly 

 point. The latter was 

 found by Mr. Norman in 

 Ascidians from the northern 

 coasts of England, the rest 

 were all found by Mr. Brightwell. We should be 

 glad to hear from any of our correspondents who 

 are fortunate enough to meet with specimens of 

 these rare and singular Diatoms. 



The Plane-tree— Pliny records the particulars 

 of several remarkable plane-trees, and tells us of 

 one in Lycia, that had a cave or hollow in the 

 trunk, which measured SI feet in circumference, in 

 which were stone seats covered with moss ; and 

 that Licinius Mutianus, when consul, with eighteen 

 of his friends, used to dine and sup in the cavity of 

 the tree, the branches of which, we are told, spread 

 to such an extent, that this single tree appeared like 

 a grove ; and this consul, says our author, preferred 

 sleeping in this hollow tree to his marble chamber, 

 where his bed was composed of curious needle- 

 work, and canopied with beaten gold. — Sylva 

 Florifera. 





Fig. 31. 



Fig. 32. 



