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an6\vciT> to (Siucrice. 



1.— Sealing Bottles. — It is no use trying to keep spirit in 

 corked bottles ; whatever you use, it will inevitably get out some 

 way. You must get wide-mouthed bottles with glass stoppers, 

 which can be obtained at any large chemist's. For temporary 

 purposes, a well- fitting cap of lead paper, squeezed tight round the 

 neck of the bottle, is better than cork, or cork may be supple- 

 mented by this. X. Y. Z. 



4. —Rotifers. — Yes, you may guess that from habitat. See 

 End. Brit.^ 9th ed., article Rotifers : — " A few species will appear 

 in countless numbers in infusions of leaves, etc., but their appear- 

 ance is generally delayed until the putrefaction is nearly over. 

 Species oi Rotifer and Fhilodina appear in this way." This delay 

 in their appearance probably means, that they feed on the remains 

 of the dead bacteria, etc., which have taken an active part in the 

 process of putrefaction. B. Lindsay, 



Examiner in Zoology to the Cambridge Exami?ier. 



5.— Four-footed Bird. — I cannot find any further notice of the 

 Opisthocojiia cristata, but will try to procure the original memoir. 

 The discovery is, however, not very startling, when the paragraph 

 you allude to is carefully read. The bird is not " four-footed " 

 when adult. The limb of the adult form loses its claws and be- 

 comes an ordinary wing, as you may easily suppose from the plan 

 given to the type in classification. (See the best and newest 

 English Manual of Zoology, Claus and Sedgwick, published by 

 Swan Sonnenschein). The ostrich exhibits two claws on the fore- 

 limb, which persist in the adult ; Rhea, and among carinate birds 

 the swan, have one so persisting. B. Lindsay. 



6.— Rock-Salt and Gypsum — You would find an answer to 

 your question in any elementary manual of mineralogy, i. — Rock 

 Salt is formed by the evaporation of the waters of some ancient 

 sea, in a geological epoch, when the level of the land was rising. 

 Arms of the sea would, under these circumstances, presently 

 become small inland seas, and these would gradually be dried up, 

 depositing their salt on the surface of the land, so as to result in a 

 salt plain. The Dead Sea is held to be an instance of a sea so 

 isolated, and there are many other instances. Although this is the 

 origin of rock-salt, as found in geological deposits, it will be 

 obvious that it leaves the primary origin of salt as a mineral unac- 

 counted for. How did the rock-salt originate ? From the sea. 

 How did the sea get its salt ?— Presumably by dissolving it from 

 the land. This reminds one of the famous problem raised by the 



