22S 



HARDWICKE'S SCIENCE-GOSSIP. 



[Oct. 1, 1S67. 



SPONGE WASHINGS. 



HE who possesses a microscope, and knows how 

 to use it, need not go far in search of objects. 

 Even within the four walls of his own house it is 

 exceedingly probable that one who is in earnest will 

 find enough to astonish his less enthusiastic friends. 

 It is not always necessary to visit the sea-coast to 

 obtain good marine Diatomaceee. Erom a very 

 simple and common source the student may often 

 secure a plentiful store to employ his- leisure and 

 his microscope. Such home resources and simple 

 expedients are amongst the charms of domestic 

 microscopy ; and the excuses sometimes urged of 

 want of leisure, claims of business, town location, 

 and inability to travel, are overturned when the 

 Diatoms travel to one's own door. It is a reversion 

 of the old saying, that if the mountain will not 

 come to Mahomet, Mahomet must go to the moun- 

 tain. 



Some twelve years ago, being in want of a sponge 

 for use in the stable, I purchased one from a hawker 

 of such commodities for the small sum of half-a- 

 crown. It was one of the coarsest and commonest 

 kind, full of large holes, and with little of external 

 favour to recommend it. This was a home lesson, 

 read by a sponge, on the folly of rash conclusions 

 from mere appearances. After repeated washings 

 in water, this sponge yielded me a large quantity of 

 sand from its interior. After allowing the larger 

 particles to subside, I boiled the lighter portion iu 

 strong nitric acid ; and having carefully washed it 

 several times in water, obtained some very interest- 

 ing slides for my cabinet. Lists are never very 

 readable or acceptable communications, and a dry 

 list of Latin names is least of all attractive to the 

 general reader ; but the following enumeration will 

 give some idea of the hidden treasures of a 

 sponge : — 



The genus Campylodiscus is represented in my 

 "washings " by no less than three species. One of 

 these is the Campylodiscus notatus of Greville, 

 which is distinguished by the central markings, 



Fig. 226, X 500. 



Fig. 22", X 250. 



which Mr. Norman has aptly compared to the 

 figure of a dumb-bell. My specimen measures 

 •0020 of an inch (fig. 22G). 

 The second representative of this genus resembles 



Campylodiscus ralfsii, but it is larger, measuring 

 •0035 of an inch (fig. 227). 



The third species is un- 

 doubtedly Campylodiscus 

 parvulus of Smith, though 

 larger than is usual in Bri- 

 tish specimens; it measured 

 •0022 of an inch (fig. 228). 

 By some this species is re- 

 garded as a variety of Cam- 

 pylodiscus fastuosa (Ehr.). 



The form called Auliscus sculptus by Smith, or, 

 as it is sometimes named, Eupodiscus sculptus, is 

 abundant in my washings, and varies greatly in 

 size. The specimen figured (fig. 229) measured '0017 

 of an inch. 



Fig. 228, x 500. 



Fig. 229, x 500. 



Fig. 230, x 250. 



There is also a fine Triceratium, which appears 

 to be the Triceratium Thwaitesianum of Greville, 

 described by him in the second volume of the 

 " Transactions of the Microscopical Society of 

 London" (new series). Dr. Greville's specimens 

 were from the Cape of Good Hope. The size of 

 the specimen figured is '0040 of an inch (fig. 230). 



Another species of Triceratium of a singular form 

 is the Triceratium pentacrinus of Wallich, which 

 was also found in my " washings." This form is 



Fig. 231, x 500. 



regarded by some authorities as a five-sided variety 

 of the Amphitetras ornata of Shadbolt (fig. 231). 

 My specimen measured '0033 of an inch. 



Amongst the better known species found on my 

 slides are the Surirella fastuosa of Ehrenberg, a 

 common marine form, diffused almost all over the 

 world, since it has been recorded in Europe, Asia, 

 Africa, and America. The specimen figured (fig. 



