Nov. 1, 1865.] 



SCIENCE-GOSSIP. 



251 



edges of the sand-ripples on the sea-beach, where 

 the furrows left by the retired tide stand filled with 

 water. Tlie edges of those furrows often present 

 a more or less dark ocherous brown appearance, and 

 that peculiar colour is caused by myriads of diatoms, 

 which, under ordinary circumstances, lie buried in 

 the sand, having risen to the surface attracted by 

 the sun's light and heat. To prevent disappoint- 

 ment, it may be said that in searching for diatoms 

 on the beach, it is possible that for several days, or 

 it may be weeks, few or no indications of their 

 presence may appear ; but if the search be continued 

 with perseverance, success will certainly reward the 

 investigation. It is difScult to account for the 

 ckanges which take place in the times and circum- 

 stances in which diatoms appear on the sea-coast. 

 I have seen them in great abundance in July and 

 August of one year, and in the next year, although 

 the weather was bright and appeared favourable, 

 they have not made their appearance in large 

 numbers until September or October, and then the 

 beach was covered with matter of a deep cofPee-brown 

 colour, which, on being gathered and examined, was 

 found to consist entirely of diatoraaceous frustules. 



The apparatus requisite for hunting diatoms on 

 the sea-coast are, half-a-dozen two oz. bottles, one 

 four oz. bottle, with wide mouth, and an ordinary 

 dessert spoon. The best method of gathering is to 

 take the spoon, and with it shave oE the ocherous 

 brown matter that lies on the surface and colours 

 the sand, put it, with the sand and water that are 

 taken up at the same time, into the wide- mouth 

 bottle. When the bottle has been half filled with 

 colouring matter, sand, &c., let it be well shaken ; 

 the sand immediately subsides, and the water is left 

 tinged with a more or less deep cloudy-like brown, 

 all of which colouring matter consists of diatomaceee. 

 When the bottle has been shaken, and the sand 

 allowed to subside, which it does almost instantly, 

 then the supernatant fluid shoald be poured into a 

 clean bottle, the contents of which would then con- 

 stitute the gathering ; the sand may be thrown away, 

 and the large bottle cleaned in readiness for another 

 collection. The following new forms, together with 

 about one hundred others, registered in " Smith's 

 Synopsis," and "Pritchard's Diatomacese," are to 

 be had in large numbers near the high, middle, and 

 low tide marks. Near high tide mark Attheya 

 decora, Cocconeis excentrica, Navicula clepsydra, N. 

 trevelyana, Donhinia carinatum, &c. ; and at the 

 middle and low tide zones, the following forms 

 abound -. — Pleurosigma lanceolatum, P. arcuatum, 

 Donkinia rectum, D. carinatum, D. minutum, Brurid- 

 gia geminata, Toxonidea Gregoriana, T. insignis, 

 Bucillaria cursoria, &c., nearly all of which are very 

 beautiful, and the majority of them so delicately 

 marked as to afford the best possible means of 

 testing the excellence of first-class objectives. 



Newcastle-on-Tyne, T. P. Bakkas. 



"HOMES WITHOUT HANDS." 



^NOTWITHSTANDING the recent and very 

 -'-^ interesting volume on this subject, it is not 

 yet exhausted. Presh facts may be gathered about 

 what has already been done, and result in the con- 

 templation of animal life in the highest phases of 

 its intellectual or instinctive development. The 

 infinite variety of means by which one end is to be 

 attained is marvellous. To multiply its kind, and 

 provide a home and shelter for its future offspring, 

 is the great idea which pervades aU forms of life, 

 This is more or less elaborated in different indi- 

 viduals, but in all the same object is paramount. 

 Two or three instances may be given here, which 

 possess in themselves another interest, of an 

 economic character. 



Tbesala. — A singular substance has long been 

 known in the East under the name of Trehala or 

 Tricula. It consists of oval cases from half to 

 three-quarters of an inch in length, found attached 

 by one side to twigs of a species of Syrian Bchinops. 

 The external surface is rough and irregular, nearly 

 of the colour of Sicilian manna, hard, brittle, and 

 with a sweetish taste. These cases are constructed 



Fig. 1. Trehala, 



by a little beetle {Larinus siibrugosus, Chevr.), of 

 which a figure is given (fig. 1). "It appears that 

 tlie larva of the Lannus collects a considerable 

 quantity of saccharine and amylaceous matter, 

 which it procures from the Echinops, and that it 

 constructs its dwelling by disgorging this matter 

 and moulding it with its rostrum." Each case 

 contains only one individual, and when this has 

 assumed its perfect form it emerges from the orifice 

 at the upper end. There is much in the history and 

 economy of this little insect which is still a mystery 

 to us, but enough is known to make us wish for 

 more. Analysis of these curious nests has shown 

 that they contain gum, starch, and sugar in their 

 composition, and when thrown into water, at the 

 ordinary temperature, ■ they swell, partly dissolve 

 and become converted into a pasty mass. In Turkey 

 and Syria they are collected and employed as food, 

 many being sent to Constantinople and other 

 Turkish cities, where they are regularly offered for 

 sale. Some of this substance was exhibited in the 

 Turkish department of the Great Exhibition of 

 1851. The insect itself is of an oblong form and 

 black, about three-fifths of an inch in length, lit, 

 snout is projecting, with the antennae attached ou 



