Nov. 1, 1S67.] 



HARDWICKE'S SCIENCE-GOSSIP. 



247 



be seen graudally losing their dirty appearance. I 

 once saw another way of managing skeleton leaves 

 that interested me greatly. The leaves were boiled 

 for two minutes, and then transferred to a strong 

 solution of permanganate of potash and gently 

 heated. In an hour or two the laxcr tissues were 

 easily removed by means of a brush. Sulphurous 

 acid was used for bleaching them, and this liquid 

 also employed with much facility for the removing 

 of the stains on the fingers caused by the perman- 

 ganate of potash. George Newlyn. 

 Dangstein, Petersfelrf. 



FRESH-WATER SPONGE. 



[Spongilla Jiuoiatilis.) 



T HAD often heard and read of fresh-water 

 -*- sponges, and, in consequence, endeavoured to 

 find them, but was never successful till May of this 

 year. Previous to that time, I had often found the 

 spicules in boilings of diatoms, and therefore sus- 

 pected the sponge's existence in the canal which 

 runs from Leamington to Oxford; but while col- 

 lecting fresh-water mussels for an aquarium, I 

 found a fine specimen attached to a stone. This I 

 carefully removed, and on reaching home made a 

 microscopic examination of a small portion, which 

 shewed the spicules supporting the amseba like 

 particles, forming the living part of the sponge. 



Afterwards, I found other specimens, in which I 

 was able to view the system of currents, so charac- 

 teristic of the class Spongidae. The sponge is a 

 variously shaped mass, rough and firm to the touch, 

 of a greenish colom - , attached to stones, in crevices, 

 and other dark spots, at a depth in the water of 

 from two to three feet. 



Running throughout its substance are a number 

 of small channels, opening at the top into larger 

 openings, called oscula, or exhalent orifices. Be- 

 tween these are smaller openings, called the pores, 

 or inhalent orifices. By watching carefully, there 

 may be observed a current from the oscula, setting 

 outwards, fed by the inward current of the pores. 

 If the sponge is cut open, the channels are observed 

 to be dilated at intervals, and in the chambers thus 

 formed, are placed the means for producing the 

 currents. Each of the sponge particles lining these 

 cavities is provided with a vibratile cilium, and by 

 the constant waving of these cilia in one direction, 

 the exhalent current is produced. This current 

 can only be seen at times, as its action is not con- 

 tinuous, only taking place when required. 



The main object of these currents is doubtless 

 the supply of the sponge with food ; as the current 

 moves along, laden with nutritive particles, each 

 inhabitant of the sponge appropriates what he 

 requires. It also serves purposes of respiration, 

 and removes foetal products. 



The propagation of the sponge during the 

 summer is of a sexual character. Certain sponge 

 particles become ova, and others fill with granules, 

 which become converted into spermatozoa. The 

 impregnation effected, the ovum develops into a 

 perfect sponge. This can be observed only during 

 the summer. 



Having left my sponges for four weeks, on going 

 to them afterwards, in August, I found the bottom 

 layer full of seedlike bodies, the " winter germs," in 

 fact. Each of these bodies consisted of a hard coat, 

 inclosing the germs inside. This coat was com- 

 posed of spicules, each of which resembled two 

 toothed wheels, joined by an axis, with a small 

 opening at one part. In November, the sponge 

 dies down, and the germs remain till spring, when 

 they develop into sponges like their parent. 



Besides the common form, there is also a branched 

 species. This must be looked for attached to 

 timber, and is the favourite food of swans. 



The spicules of the Spongilla are straight, and 

 pointed at both ends. The germ case spicules are 

 much smaller than the others. Great care is 

 necessary, after boiling in nitric acid, to remove 

 extraneous matter. G. T. 



NEST OF WOOD WASP. 



(Vespa holsatlca.) 



T^ARLY in the month of May this rather un- 

 -*-^ common wasp commenced building its nest 

 in the south-east porch of my rectory ; and as it is 

 a somewhat rare insect about here, and as Mr. 

 Smith, the great authority on the wasps and bees, 

 tells me he never knew the Holsatiea build above 



Fig. 250. Male and Female of Vespa holsatiea (nat. size). 



ground, although he says it may do so occasion- 

 ally, I send you a short account of it. Early in 

 May I observed a queen commencing her curious 



