HARDWICKE'S SCI ENC E-G OSSIT. 



1 1 x 



Surrey. 



Croydon. A. Bennett, 107 High Street. Flowering 

 plants, particularly Orobanches and Potamogetons. 

 Also the genera Chora and Nitella. 



Warwickshire. 

 Birmingham District, 



Birmingham. Montagu Browne, F.Z.S., Broad 



Street, Reservoir Road. General Zoology, especially 



Ornithology (European and exotic). 

 Perry Barr. W. B. Grove, B.A., Cheadle Cottage. 



Botany. 

 Aston. H. W. Jones, F.R.M.S., 183 Park Road, 



Chemistry of Zoology . 

 Aston. J. Levick, Lime Tree Villa, Albert Road. 



General Microscopy, especially "Pond-life." 



( To be continued.) 



I 



CENSUS OF EUROPEAN FLORAS. 



N glancing over a few of our standard Floras, I find 

 the proportion of families or orders is about as 

 follows. This is a very interesting study for a winter's 

 evening, and, better than anything, gives a fair know- 

 ledge of the respective districts, thus : — 



Gras. 



The 



Cruci/enr, to Phanerogamic orders 

 in 22f T ,, Flora Lapponica. 



es, to Phanerogamic orders, is about : 

 in iOj in Flora Lapponica. 

 ,, 11 ,, Flora Edinensis. 

 ,, io.\ ,, Devonshire Flora. 



Berwick-on-Tweed Flora. 



>> 



"1 „ 



12 

 1 



Flora Scotica. 



I2i 



, British Flora (entire). 

 London Flora. 



25J 



Flora Edinensis. 



I7 T 6 T ,, Devonshire Flor.i. 



2l\ 



20^ 

 20l 

 21 

 12" 



Berwick-on-Tweed Flora. 

 Flora Scotica. 

 British Flora. 

 London Flora. 

 Flora Gallica. 



)> ■•■'■7 



Cyperacea:, to other Phanerogamic orders : 



in 9 in Flora Lapponica. 



>> x 53 j> Flora Edinensis. 



,, 16 ,, Devonshire Flora. 



,, 16} ,, Berwick-on-Tweed Flora. 



,, 14.^ ,, Flora Scotica. 



„ I7i| ,, British Flora. 



,, 17} ,, London Flora. 



Thus as we proceed toward the south, many orders 

 which are purely northern, in their general distribu- 

 tion become more rare, as well as fewer species. — 



R. 



DEVELOPMENT OF THE FRESHWATER 

 SPONGE. 



By James Fullagar. 



IN the January number of this year there is a short 

 account of the growth of a small sponge in one of 

 my glasses, from which I obtained some fresh ovaries, 

 and from these ovaries several small sponges have 

 been produced, and have been very interesting objects 

 to me in watching their further growth. From 

 August up to the end of November they had con- 

 tinued to increase in size, and the skeleton spicules 

 had become very numerous. The incurrent through 

 the pores, and the excurrent by the oscula, continued 

 to flow, and these were very plainly seen when a small 

 quantity of carmine was placed in the water. From 

 December up to February the sponge has not made 

 much progress, though it has constantly been supplied 

 with fresh river water. The excurrent from the oscula 

 is now quite suspended, and I rather doubt whether 

 the sponge will perfect itself and again produce the 

 ovaries, the production of which I had hoped to 

 witness, but I must now wait until next August before 

 I shall be able to procure a fresh supply of ovaries. 

 On the ovaries being left out of water they become 

 cup-shaped (fig. 65) by the contraction of the upper 

 half inwards, in the process of drying, and in this 

 condition the foramen appears at the bottom of the 

 cup (fig. 65, a) ; placing them in water for a short time 

 restores them again to their spherical form. The 

 production of the flinty spicules in the sponge is 

 truly wonderful, when we consider their rapid growth 

 and delicate forms, transparent as glass, composed of 

 pure silica. As we are informed that water holds in 

 solution so small a quantity of silica as from one to 

 two grains only in a gallon, the process of extracting 

 it by sponge appears marvellous. Some of the spicules 

 at first are inflated in the centre (fig. 66), some of them 

 have two or three of these enlargements, which 

 probably diminish in bulk as the spines extend, and 

 are lengthened out to the shape at fig. 67, this being 

 their normal shape. Bowerbank does not mention 

 this form of spicula as occurring in S. fluviatilis. 

 Could we have overlooked them ? I do not think 

 this possible ; but, be it as it may, I have now by me 

 in the young sponges many of the inflated form, and 

 some of them with as many as six protuberances, 

 occupying nearly the whole length of the matured 

 spicule ; on the other hand I have a mounted slide of 

 the common shape spicula, containing some hundreds 

 of them, but not one inflated form among them, so 

 that they appear not to be a constant form. The 

 spicula peculiar to the ovaria I have endeavoured to 

 sketch in fig. 68, having boiled them in nitric acid, by 

 which the coriaceous skin covering them was destroyed, 

 and the spicules were liberated. When mounted in 

 dammar they form very pretty objects for the micro- 

 scope. In fig. 68 are sketched some of them pressed 



