HARDWICKE'S SCIENCE-GOSSIP. 



69 



correspondent W. H. Rean in regard to feeding. 

 Meat, which he recommends, is never entirely 

 digested by anemones, but is voided after a time, 

 and often spoils the water by putrefying in some 

 unnoticed corner. I found a small portion of the 

 white of a boiled egg free from this objection, and 

 that it was readily taken by anemones, prawns, 

 crabs, &c. The starving system recommended by 

 W. H. Rean must cause many of the anemones to 

 remain unexpauded for days together. They appear 

 to greatest advantage ^fter being fed, and a fine 

 JDianthts after a meal is a sight to be remembered. 

 Many failures with aquariums are caused by a bad 

 aspect. By far the best aspect is one near a window 

 facing due north. A marine aquarium in which the 

 water is deep, is a constant source of vexation to its 

 owner, and can only be made to succeed by having 

 a stream of water constantly running through it ; 

 an arrangement which few can attempt. It is best 

 to have the deepest part of the water in front, and 

 to pile up the rockwork at the back till it reaches 

 the surface of the water. It is well to aerate the 

 water daily with a glass syringe. When once a 

 supply of sea-water is obtained, not a drop need be 

 wasted, even though, through the death and putre- 

 faction of some of the animals, it is opaque and 

 smells offensively. _ It can be restored to its origi- 

 nal purity by exposing it for a few days in a shallow 

 vessel to the open air. To compensate for loss by 

 evaporation, fresh water should be added. — F. G. 

 Watford. 



Horse-Chestnut. — When in Paris in September 

 last, I was struck by the remarkably wintry appear- 

 ance which the deciduous trees had already assumed : 

 a remarkable exception was a young horse-chestnut 

 {JEsculus Hypocastanum), which had not merely ex- 

 panded many young leaf-buds, but several spikes of 

 flower in full bloom, though the blossoms seemed 

 individually small. Is not this an unusual occur- 

 rence ? The tree will surely suffer in the spring . 

 Other specimens of the same tree had only ex- 

 panded a few young leaves, but I only saw this one 

 in blossom. — I. Q. Halliday. 



Umbilicus in Shells. — Your correspondent C. 

 Jecks wants to know what purpose is served by the 

 umbilicus present in certain univalve shells. I 

 think the only answer to this question is, None at 

 all ; it is only an accidental formation caused by the 

 peculiar shape of the shell and its whorls, a con- 

 sequence of a more or less widely-spread [coil of 

 whorls._ As far as my experience goes, it is found 

 largest in the flattest shells ; many have it in embryo, 

 which in the adult is entirely obliterated by the ex- 

 tension of the lip of the shell. By gradation, shells 

 may be traced from the slightly curved dentalium, 

 to the coiled siliquaria, which shell is more or less 

 of a spiral, but without the whorls touching each 

 other; then to shells with a large or small umbilicus, 

 till at the other end those entirely without um- 

 bilicus. I think as well might he ask, why the 

 Terebra and Clausilia should be elongated ; the 

 Zonites and Planorbis flat ; why some Helices 

 should have thickened reflected lips and some not ; 

 why some should have teeth-like processes and 

 others smooth lips ; why some shells are smooth and 

 some rough ? — T. B. B. 



The Name " Tray."— A friend suggests, and I 

 think he is probably right, that the name " Tray " 

 was first given to dogs from the trick blind men's 

 dogs are taught, of holding in their mouths a tin 

 cup, or tray, or plate, for money to be dropped in. — 

 H. Budge. 



Keeping Parrots.— 1 bought a grey parrot 

 some time ago ; he is now dead ; the only symptom 

 observable was diarrhcea. Could you or any of your 

 readers give me some practical information in regard 

 to parrots, as to the proper food, &c, and proper 

 treatment in disease, as I am in a quandary. I wish 

 to buy another parrot, and do not wish to lose him. 

 In particular I would like to know if it is proper to 

 give them water ; also, if it is well to give them a 

 bath now and then. Should they have tine sand or 

 gravel in their cage? If you could find time to 

 answer the above, either by letter or in S.-G., you 

 will greatly oblige yours obediently, /. J. M., 

 Montreal, Canada. 



New Zealand Forests.— The reason why the 

 cultivation of the native trees of New Zealand was 

 unsuccessful, as stated in Science-Gossip for 

 December last, p. 2S1, by Kaiapoi, must, I think, be 

 looked for from other causes than that suggested 

 by your correspondent ; viz. that the New Zealand 

 forest trees are approaching " the end of the period 

 allotted to their existence," especially as trees from 

 other countries gave promise, when he left, of pay- 

 ing for cultivation. It is a well-known fact that the 

 ground upon which any species of tree has lived and 

 died, will not for a lengthened period sustain the 

 same species- Wherever old forests die a natural 

 death, the trees that spring up afterwards are always 

 different. The reason is obvious. Each species 

 takes from the soil what is necessary to its exist- 

 ence ; after that, it cannot be expected that the 

 same species will thrive. There are others that do 

 not require the same nourishment, but will take up 

 as an essential what was rejected by the other. On 

 the same principle the farmer and gardener change 

 their crops, and put into the soil, in the form of 

 manure, the ingredients necessary l'or the crop they 

 intend to grow. Or perhaps the soil was not 

 naturally suitable to the trees that were tried. Any 

 one who has studied our wild plants in their native 

 homes, cannot help observing that many species 

 are peculiar to particular formations ; others again 

 will grow in a great variety of soils and altitudes. 

 Some few may almost be called " Citizens of the 

 World." The above causes are more likely to 

 account for the " natives " not thriving, than that 

 they are approaching the limits of their existence. 

 Cuttings or grafts of very old trees have not such a 

 good chance of succeeding, as they are only part of 

 the old tree ; but seedlings _ of the New Zealand 

 trees if transplanted into suitable soil, will, I have 

 little doubt, live and flourish for ages to come. — 

 A. B., Kelso. 



Hardening Balsam. — Under this heading, in the 

 January number of Science-Gossip, Mr. C. C. 

 Underwood states, that if the object is small he 

 holds it down by a spring clip to prevent displace- 

 ment, and then drives off the turpentine by boiling, 

 so that the balsam is left in such a condition that 

 the cover will never be displaced. As far as the 

 balsam itself is concerned, I quite agree with his 

 statements, and for some specimens his modus 

 operandi is, doubtless, very efficient, but at the same 

 time, there are some which will be entirely spoiled 

 if [subjected to this treatment. All animal tissues, 

 if boiled in the manner described, will contract or 

 shrivel up to such an extent, that, if the same sec- 

 tion be examined before and after boiling, it will 

 scarcely be recognized as the same structure ; there- 

 fore, for this class of specimens I would strongly 

 recommend that, instead of being boiled, the thin 

 cover (after the slide is otherwise complete) should 



