386 



JOtJENAL OP HOETlCtJLTUEE AND COTTAGE GAEDENEE. 



[ May 9, 1872. 



aphides, which are born alive. A most curious fact this, and 

 one that I can only lightly touch upon here — namely, that in 

 the same species the females arc at one time oviparous and at 

 another viviparous. All through the season of vegetable growth 

 and active life, brood after brood of aphides is ushered into 

 existence without the intervention of any male insects, and 

 without passiug through the egg condition. It is only when 

 aMtumu has fairly commenced to strip the trees that we 

 observe on the Rose bushes individuals with bodies of 

 orange or brown, and endowed with wings of a deeper tint 

 than their female companions. These are male aphides, and 

 the result of their life is the deposit of a batch of eggs, which 

 carry on the species in safety to another season. It is only the 

 change of temperature which has brought these forth, and 

 during exceptionally mild winters a species of aphis has been 

 noticed to continue viviparous, and under artificial waiinth in 

 a greenhouse for several years. 



The subject of aphis life has engaged the attention of some 

 of the most distinguished naturalists here and on the Con- 

 tinent, but, for all that, we cannot state that it has been 

 satisfactorily investigated. With the best intentions, most 

 have investigated theii' structure and habits in order to sup- 

 port some ingenious theory. A number of successive genera- 

 tions of aphides appear, amongst which no male insects are 

 found — that is a fact unquestionable, and how is it to be ex- 

 plained ? A considerable sensation was occasioned a few years 

 since by the discoveries of M. Balbiani, who from his dis- 

 sections, was led to conclude that during the time they are 

 viviparous, apliides are true hennaijhrodites, performing the 

 fimctions of both sexes in female guise. Shortly after M. 

 Meezikow, and Professor Claparide, who had been investigat- 

 ing the matter about the same time, wrote expressing theu' 

 conviction that M. Balbiani was wrong both in his conclusions 

 and in his seeming discoveries ; nor do I think that the 

 " hermaphrodite " supposition has gained much support in 

 England. 



A few words may be added to this paper concerning the 

 migration of aphides, on one point where popular beliefs have 

 gone wrong. They can only travel long distances, if travel 

 they do, in one of two ways — by means of their own wings, or 

 by being carried along by winds , or in the clouds , as some persons 

 think. That they do not journey by their own power of 

 flight to any great distance is self-evident, nor is it likely at 

 all that atmospheric agencies transmit them from one dis- 

 trict to another. I have heard gardeners in our suburbs west 

 of London, lamenting over the fact that the green or black 

 blight of eastern London travelled with the easterly winds in 

 search of " fresh fields and pastures new," but I am quite con- 

 vinced that this is only imagination. — J. E. S. C. 



VEGETABLE AND ANIMAL LIFE. 



What though we may be unable to explain what life is, it 

 may still be proper to examine into what is termed the physical 

 basis of life. It is well to bear in mind, however, that notwith- 

 standing much has been written on these subjects, the know- 

 ledge of hidden forces, motion or Ufe, soul and spirit, is no 

 better elucidated now than it was centuries ago. So that we 

 can with propriety adopt the Scripture language, found in 

 Hebrews xi. 3.—" Through faith we understand that the worlds 

 \vere framed by the word of God, so that things which are seen 

 were not made of things which do appear." This is the 

 positive fact, and science cannot in truth gainsay it. 



Let us briefly consider what science knows of the so-called 

 essential elements of life— carbon, hydrogen, oxygen, and 

 nitrogen. 



Carbon— a pure combustible base of the varieties of charcoal 

 and other carbonaceous matter. Charcoal is burned wood, or 

 burned bone, or leather, both previously organised, whether 

 from the vegetable or animal creation. What is very remark- 

 able, however, is that the diamond, being a mineral, is pure 

 carbon in crystaUised form. As an elementary substance, car- 

 bon combines with oxygen in two proportions, forming carbonic 

 acid and carbonic oxide. Carbonic acid consists of 6 car- 

 bon X 16 oxygen = 22. This extinguishes flame and suffocates 

 animals ; as found in wells and mines it is called choke damp. 

 Limestone, mai-ble, and chalk contain it. Carbonic oxide is 

 composed of 6 carbon x 8 cxygen == 14. It is fatal to animals 

 and extmguishes flame, but it burns in contact with ah-, and 

 forms carbonic acid. 



We will now briefly consider oxygen, so efficient in forming 

 acul compounds, as weU as eight-umths of the weight of water. 



one-fifth of the weight of the atmosphere, and is present (often 

 to the amount of from forty to iifty per cent.) in nearly all the 

 mineral bodies of which the crust of the globe is composed, in- 

 cluding the soil. 



The magnetic properties of the atmosphere are sTiid to be 

 almost exclusively due to the oxygen contained in it ; modified 

 by its action by solar heat, it occupies a high position among 

 electro-negative bodies. It is just as likely that electricity is 

 associated with the oxygen in the air, which — for instance when 

 brought under the rubber of an electric machine — separates it 

 by the oxygen acting upon the amalgam, and Uberates the 

 electricity, which, having a greater affinity for the metalhc 

 conductors than for the air, is conveyed to the Leyden jar, 

 and confined until discharged. Electricity is only a modifica- 

 tion of creative force, and is more nearly related to life than 

 the ponderable elements upon which it acts through the in- 

 fluence of solar Ught or otherwise. Though the sun's rays are 

 not fire, yet bring them to a focus by a lens, and fire is a re- 

 sult in contact with combustible bodies. 



Hydrogen is only known in its gaseous form, formerly called 

 inflammable air, and considered identical with the matter of 

 heat. Pure hydrogen is .sixteen times lighter than oxygen; it 

 burns in contact with air with a pale flame, and when mixed 

 with three or four times its volume of air (or half its volume in 

 jjiu'e oxygen) and inflamed, it burns rapidly, and in the latter 

 case with violent explosion. The only product of this com- 

 bustion is water. How marvellous ! and yet hydrogen is not 

 absorbed by water, and animals soon die when confined m it. 

 So we come to consider water, which was itself considered an 

 clement by the older chemists, but we have just seen that it is 

 a compound of hydrogen and oxygen, as supposed by Watt 

 and Cavendish, as far back as a.d. 1786 and 1787, and since 

 satisfactorily demonstrated. Thus water is in fact an oxide 

 of hydrogen, scientifically considered. But water is seldom 

 purely such ; there are mechanical, gaseous, mineral, and or- 

 ganic impurities in it ; changing in its descent as pure rain- 

 water, it becomes charged with the gases of the atmosphere, 

 such as oxygen, nitrogen, and carbonic acid, and during a 

 thunder storm air appreciable quantity of nitrate of ammonia 

 produced by electric discharges through moist air ; and it is a 

 source of fertility to vegetation, further augmented by its 

 holding in solution small quantities of mineral salts, and gene- 

 rally of organic matter. 



The remaining element to be considered is nitrogen, also a 

 simple gaseous body, forming a constituent of the atmosphere 

 and of nitric acid ; this being also antagonistic to hfe, is hence 

 also called azote. It is, nevertheless, an important comiJonent 

 of many organic substances, and is remarkable as one of the 

 fulminating compounds of gold, silver, and mercury, to say 

 nothing of gunpowder — a compound of sulphur, nitre, and car- 

 bon. Thus we learn that these elements arc mostly dele- 

 terious to life, and yet essential to sujiport it. 



Thus we learn that vegetables produce azotiscd substances, 

 the fatty matters — starch, gum, and sugar — which are consumed 

 and form the food of animals, and from this consumption is 

 produced carbonic acid, water, and ammonia, which latter pro- 

 duct is in turn decomposed by vegetation, and in that de- 

 composition oxygen is evolved, so essential to the animal, 

 in return for the carbonic-acid product given out by the 

 animal, and so essential to vegetation. — (American Cardtncr's 

 Monthly.) 



The Gakden of the Acclimatisation Society of Paris, 

 ruined during the siege, is about to be reopened. A great part 

 of the damage has been repaired, the ornamental and horticul- 

 tural parts have been replaced, and there are already many 

 animals in the park. — (Nature.) 



DINNEE-TABLE DECOEATIONS BY GASLIGHT 

 AT THE BIEMINGHAM SHOW. 



I WISH to draw attention to this class in the schedule of 

 prizes, in which it stands as follows : — 



" Class 145. — Dinner-table decorations by gasUght. Dinner 

 table completely laid out for fourteen persons, and arranged so 

 as to show the best means of utilising fruit and flowers in its 

 adornment. The exhibits wiU be judged and exMbited by gas- 

 hght. Open prizes, £20, £15, £10, and £7." 



I find some misapprehension exists as to the time when these 

 dinner- table displays will be exhibited — the words " by gas- 

 Ught " having led some to suppose that they are to be seen in 



