SCIENCE. 



6 9 



natives of South Africa, and those of some of the Sunda 

 Isles esteem dragon-flies a great delicacy, catching them, 

 according to Wallace, on birdlimed twigs. Though there 

 can be comparatively little nutriment in the soft bodies of 

 insects, yet there is no reason for the horror with which 

 they are regarded, as articles of food, by the Aryan races. 

 A fancy for the flavor of the Rocky Mountain locust would 

 go far toward decreasing the devastation of that dreaded 

 pest. 



Some of the marine worms are accounted delicacies by 

 certain tribes, but the greater part of the varied forms be- 

 longing to the sub-kingdom must be regarded, so far as 

 they are useful to man at all, as only indirectly so through 

 their consumption by animals he feeds upon. The same 

 may be said of the Protozoa, which, swarming in countless 

 numbers in sea and river, lake and marsh, furnish food for 

 the creatures above them. 



Putting aside all question of protection or preservation 

 of plants and animals now used as food, the examples ad- 

 duced are sufficient to show that the range of foods might, 

 with advantage, be greatly extended. 



Much remains to be learned respecting the diseases and 

 bodily states of cold-blooded animals and of the inverte- 

 brata before we can use them for food with the same confi- 

 dence with which we eat beef, mutton or poultry. The 

 diseases of the higher animals are, to a great extent, similar 

 to our own, and we have learned how to discriminate ; but 

 we do not recognize the diseases of fishes, crabs and shell- 

 fish. The stories of poisonous fish probably arise from this 

 source. Every year we hear of cases of poisoning, well 

 authenticated, from eating mussels, lobsters or other Crus- 

 tacea, or mollusks, which are usually healthy food. All 

 these creatures are subject to diseases which we have not 

 yet studied, and it may be that at certain seasons, such as 

 immediately after reproduction, some of them are unfit for 

 food. This is one well-grounded cause of prejudice, but 

 one which will be removed as our knowledge of the lower 

 forms of life extends. 



The animal and vegetable world furnish us with other 

 things besides food. Materials of other descriptions fur- 

 nish, by their manufacture, a means of procuring food to 

 some, while the articles manufactured are of use to all. 

 Commerce, which has made us familiar with foods pre- 

 viously unknown, has helped us still more in this direction, 

 yet when we consider the great variety of vegetable and 

 animal life, we cannot but believe that much more remains 

 to be discovered, or, at least, utilized. 



Other nations, many of them but semi-civilized, others 

 barbarous, have, in these things, been our teachers. As 

 maize and potatoes were known to the Indians before we 

 learned to use them, so was Phormiumtenax to the Maoris, 

 and cotton to the Hindoos and Chinese. 



When it is remembered what vast industries depend upon 

 the supply of fibrous plants, and, that a fibre with different 

 qualities, as it could be applied to new uses, would start a 

 new branch of trade ; when we see how extensive are the 

 manufactures carried on from gum-resins like caoutchouc, 

 or gutta-percha, we must acknowledge that the discovery of 

 a fiber or a resin with new uses would furnish a livelihood 

 to many additional workers. Take paper for example. 

 Until lately this article was made from linen rags, but as 

 the supply of that material fell short of the demand, cotton 

 waste, siraw, the Yucca plant, and other vegetable materials 

 came into use, and it is evident that it can be made from 

 almost any fibrous substance reduced to a pulp. Few are 

 the plants that cannot be utilized by man. If valueless for 

 food or for building purposes, a fiber, a gum, an essential 

 oil, a medicinal product, may be found in most. 



The constantly-increasing stock of geographical and bo- 

 tanical knowledge brings new materials into the notice of 

 scientists, and the constantly increasing needs of mankind 

 brings them slowly into public notice. The secretion lately 

 found in Arizona, upon the branches of Larrca Mexicana, 

 and of another plant, may yet enable us to dispense with 

 the imported lac from Asia. Chemically the two seem 

 identical ; practically the despised Indian, here again our 

 teacher, has long ago proved its use in the mending and 

 making of vessels for cooking purposes. 



Here is ^ case of a new material furnished by the animal 

 kingdom, for it appears almost certain that the secretion, 

 like that of wax or honey, is elaborated by the insect from 

 the juices of the piants it feeds upon. Insects, so little 

 used for food, so terribly destructive to our food plants and 

 annoying to our domestic animals, may yet yield to us many 

 useful materials ; may yet prove in this respect among the 

 most useful of organisms. Silk, honey, wax, gum-lac, 

 cochineal, all are insect products, elaborated by insects 

 from plants ; and the last two are the produce of coccidce, 

 those destroyers of our orchards and orangeries. Does not 

 this point a way to the utilization, in some cases, of our 

 insect pests ? 



The higher animals may not furnish us with many addi- 

 tional materials. Horn, hair, fur, wool, hides, feathers, 

 bone, ivory, have their known uses. Improvement here is 

 to be looked for rather in new uses for known materials 

 than in the discovery of new ones. But the lower animals 

 may yet yield us many useful substances. The great trea- 

 sure house of the sea holds more than we have ye; learned 

 the use of. Shells, corals, the honey axes of soft-corals, 

 and many other portions of marine animals, may be utilized 

 for something more than show ; and other secretions maybe 

 found as useful as those of the sepia. But though the 

 number of useful species — useful either directly or indirectly 

 — is so large that it includes probably the greater portion of 

 existing organisms, yet some are far more useful than 

 others, and some are directly injurious to more useful 

 organisms. Such species need not be cultivated, except 

 where they do not come into direct competition with more 

 useful ones ; but their consumption or use by man would 

 diminish their numbers and give room for the more useful 

 forms, which are now often permitted by man, even in his 

 own cultivated fields, to be crowded out by the less useful. 

 — Scientific Press, Cal. 



Two eggs of the extinct great auk were sold by auction 

 in Edinburgh recently, both being purchased by Lord Lil- 

 ford, one at ^ioo, the other at 102 guineas, probably the 

 largest sum ever paid for a single egg, with the exception 

 of that of the moa, a single specimen of which was sold at 

 the same place in 1865, for ^200. 



Progress in Utilization of Solar Heat. — Since May, 

 last year, M. Mouchot has been carrying on experiments 

 near Algiers with his solar receivers. The smaller mirrors 

 (0.80 m. diameter) have been used successfully for various 

 operations in glass, not requiring more than 400 to 500 . 

 Among these are the fusion and calcination of alum, pre- 

 parations of benzoic acid, purification of linseed of oil, con- 

 centration of syrups, sublimation of sulphur, distillation of 

 sulphuric acid, and carbonization of wood in closed vessels. 

 The large solar receiver (with mirror of 3.80 m.) has been 

 improved by addition of a sufficient vapor chamber and of 

 an interior arrangement which keeps the liquid to be vapor- 

 ized constantly in contact with the whole heating surface. 

 This apparatus on November 18, last year, raised 35 litres 

 of cold water to the boiling point in 80 minutes, and an 

 hour and a half later showed a pressure of eight atmos- 

 pheres. On December 24 M. Mouchot with it distilled 

 directly 25 litres of wine in 80 minutes, producing four 

 litres of brandv. Steam distillation was also successfully 

 done, but perhaps the most interesting results are those re- 

 lating to mechanical utilization of solar heat. Since March 

 the receiver has been working a horizontal engine (without 

 expansion or condensation) at a rate of 120 revolutions a 

 minute, under a constant pressure of 3.5 atmospheres. The 

 disposable work has been utilized in driving a pump which 

 yields six litres a minute at 3.50 m. or 1,200 litres an hour 

 at 1 m., and in throwing a water-jet 12 m. This result, 

 which M. Mouchot says could be easily improved, is ob- 

 tained in a constant manner from 8 a. m. to 4 P. M., neither 

 strong winds nor passing clouds sensibly affecting it. 



