CIHM ICI\AH Microfiche Collection de Series microfiches (Monograplis) (monographies) 1 1 1 I El I CaMdiM liwtitun for HtolOfieal MIcronproductioro / Initltiit caiMdian d. micronproductlom htotoriqiiM 1995 Technical and Bibliographic Notes / Notes technique et bibliographiques The Institute tias attempted to obtain the tiest original copy available for filming. Features of this copy which may be bibliographically unique, which may alter any of the images in the reproduction, or which may significantly change the usual method of filming are checked below. D Cokxjred covets / Couveiture de couleur [ I Covt.s damaged/ — Couverture endommag^e I I Covere restored an*or laminated/ Couverture restaui«e et/ou pellicul«e Q Cover title missing /Le litre de couveiture manque Q Coloured maps/ Cartes giographiques en couleur [~~] Coloured ink (i.e. other than blue or black)/ Encre de couleur (i.e. autre que bleue ou noiie) I I Cotoured plates and/or illustrattons/ Planches ot/ou illustrations en couleur [3^ Bound with other material/ — Reliiavecd'autiBS documents Only sditkin available/ Seule ^ditkm disponible Tight binding may cause shadows or distortion along interior margin / La reliure ssrrte peut causer de I'ombre ou de la distorsion le long de la marge imerieuie. Blank leaves added during restotaltons may appear within the text. Whenever possible, these have been omitted from filming / II se peut que certaines pages blanches ajouttes tors d-une restauratian "Pparaiisent dans le texle, mais, kwque cela «tal possible, ces pages n'ont pas «I6 (ilni«es. D D D B' L Institut a microfilms le meilleur examplaire qu'il lui a 6 e possible de se procurer. Les details de cet exem- plaire qui sent peut-6tre uniques du point de vue bibli- ographique. qui peuvent modifier une image reproduite ou qui peuvent exiger une modifications dans la m«h- ode nomiale de filmage sont indiquAs cl-dessous. I I Cokxired pages/ Pages de couleur I I P^aes'to'raged/ Pages endommagies [~~| Pages restored and/or laminated / Pages restaurtes et/ou pellicuMes [T^ '"^9*' discoloured, stained or foxed / Pages d«cok>r«es, tachel«es ou pk|u«es Q Pages detached/ Pages d*tach«es p] Showthrough/ Transparence I I Quality of print varies / — ' Qualit* in«gale de I'impresston I I Includes supptementaiy material/ Coitprend du materiel suppKmentaire I I P'9«« wholly or partially obscured by errata slips, tissues, etc., have been refilmed to ensure the best possible image / Les pages totalement ou partiellement obscurcies par un feuillet d'errata, une pelure, etc., ont «te filmees a nouveau de fajon k obtenir la meilleure image possible. I I Opposing pages with varying colouration or discolourattons are filmed hvtoe to ensure the best possible image / Les pages s'opposant ayant des colorations variables ou des decol- orations som fllm«es deux fois afin d'obtenir la meilleur image possible. Adtiltonal comments / Commemains SMppWmenlalres: Pegfnatfon is u follian i p. [S3]-99. Thii itMn is f Hmad at th< rsduction ratio dMckad btkiw/ Ct docwMiit ait film* au taux de rMuction tntuvit CMiauous ">" 14X 1IX t2X ItX sx nx 2DX 26X MX L _ ~ 24X 28X ^^■nd ^ ' 12)1 Tha copy fllmid h*ra hM ba«n rtproduead thanks to tha ganarotity of: Oalhoumle Uhlverftlty a.K. Kallogg Hulth Sclencai Library Halifax Tha imaga* appaaring hara ara tha baat quality posilbla contidaring tha condition and lagiblllty of tha original copy and in kaoping with tha filming contract spaciflcationa. L'axamplaira filmt fut raproduit grica i la ginirotit* da: Dalhoual* Unlvaralty I.K. Kallogg Haalth Sciancas Library Halifax Las imagaa suivantas ont M raproduilas svsc la plus grand soin. compta tanu da la condition at do la nattata da l'axamplaira fjima. at »n conformM avac las conditions du control da filmaga. Original eoplos In printad papar covora ara fllmsd baginning with ttia front covar and anding on tha laat paga with a printad or illuatratad Impras- slon, or tha back covor whan appropriata. All othar original copiaa ara filmad baginning on tha first paga with a printad or illuatratad Impraa- sion, and anding on tha laat paga with a printad or illuatratad impraaaion. Laa aaamplalraa origlnaux dont la couvartura an papiar ast Imprimts sont filmts an eommancant par la pramlar plat at an tarminant soit par la darnitra paga qui comporta una amprainta d'Imprasslon ou d'illustratlon, soit par la sacond plat, salon la cis. Tous laa autras axamplairas origlnaux sont fllmM an commandant par la pramlAra paga qui comporta una amprainta d'imprsasion ou d'illustration at an tarminant par la darnitra paga qui comporta una talla amprainta. Tha laat racor4ad frama on aach mlcroflcha shsll contain tha symool — *' (moaning "CON- TINUED"), or tha symbol ▼ (maaning "END"), whiehavar applias. Mapa, platas, charts, ate, may ba filmad at diffarant raduction ratios. Thoso too larga to ba antiraly includad in ona axposuro ara filmad baginning in tha uppar laft hand eomar, laft to right and top to bottom, as many framas as raquirad. Tha following diagrama illustrata tha mathod: [)n daa symbolaa suivants ipparaitra sur la darnitra imaga da chaqua microficha. salon la cas: la symbola — » signlfia "A SUIVRE". la symbols ▼ signlfia "FIN". Laa cartas, planchas, tablaaux. ate. pauvant Itra fllm4s i das taux da rtduetion diffarants. Lorsqua la document ast trop grand pour tira raproduit an un saul ellch*. ii ast film* t partir da I'angia supAriaur gaucha. da gaucha i droits. at da he t an baa, an pranant la nombra d'imagas ndcassaira. Las diagrammas suivants illustrant la mAthodo. 1 2 3 1 2 3 4 5 6 "WOCOfV RfSOUITION TBT OUtT (ANSI and ISO TEST CHAJIT No. 2) 1.0 I.I lit ■11 1^ 1 2.2 V^^M^ A /APPLIED IM/CE In. HOW WE DEFEND OURSELVES FROM OUR FOES Bt PBOnaiOB FRASER HARRIS, D.Sc. 'Si [B^rinted from The Pcpdlas Scibkcx Montolt, Ju]y. 1914,] [Bepriatod from Tbb PorvLu Bcnuioi Mokthlt, July, 1014.] HOW WE DEFEND OURSELVES FROM OUB FOES Bt PBoriMOB FRA8ER HARBI8, D.Bc. DALUOUBIl UNIVEBIITT, UAUFAX, N. ■, IN a certain sense even now in the midst of his civilized communities, mankind is waging ceaseless warfare against a number of hostile conditions, both animate and inanimate. Serious as this may be now, it must have been much more acute in the earlier times of the race. Man had to defend himself, as beet he could, from the great cosmic exhibitions of energy— the extremes of heat and cold, the tempest, the lightning, the avalanche, the earthquake and the tidal wave. Primitive man, we are assured, must have lived in the midst of alarms of all eorti and in the constant dread of attacks by fierce animals far more powerful than himself. Undoubtedly he sought shelter from wind, rain, snow and frost in those caverns in which his skeleton and the bones of the animals he slew for food and fur are yet to be found. In many parts of the world he built his wooden hut on piles out from the shore of some lake, so that he had his food supply in the fish under the fioor, and was also more secure against the wild animals when his dwelling had to be defended on one side instead of on four. The latent powers of his nervous system penri.'';ted him to develop that speed of running in flight whereby he scved himself from the avalanche, the tidal wave or the beasts of the field. Not alone waa speed necessaiy, but also rapidity of response on the part of his nervous system in order to take warning from the impending danger : that man lived longest who most rapidly reacted to the danger signal, stepped most agilely out of the way of the rolling boulder, skipped most briskly aside from the infuriated lion or bear. Of course, as we know, he early devised his weapons of oflfence and fired his flint-tipped arrows at the animals threatening his life or destined to be his store of food for a long time to come. That man throve best who most accurately threw hia stone or javelin, so that quickness of response (short "reaction-time") and accuracy of aim — both powers of the nervous system — were early in the history of our race the means of escape from enemies, or the mode of procuring a Bufl5ciency of food. The first human line of defence is then nervous or mental; our ancestors established themselves on the earth by means of such powers of the aervouB system aa speed, accuracy and ccnri^ination of move- 94 r//V POPULAR SCIENCE MONTflLY iricnti'; ami tlirsc arc of aiiprome importance even yet. He who jump! quitkpft out of the way of the runaway horse eacapea with his life; the oM jrcntlenian, whose reaction-time age has lengthened, does not ■tep a-nlc from the carelcj'ftly driven motor-ear sufficiently perfectly, and wo ffQU run over. Those men who after harpooning the whalj got their Imat most (|uickly out of the reacli of his tail, were nioet likely to reach the hig ship in saft'ty. He hums his fingers least who most rapidly drops the hot coal. While, now-a-days, shortness of reaction-time may only occasionally contribute to the actual saving of life, yet it does assuredly contribute towards what is called "puccess" in life. Tie who most quickly grasps a situation nf danger and nets ncordingly, has an advantage over his neighbor with the more sluggishly reacting nervous systcn. It is obviously by his development of intelligence — a power of the nervous system — that man has not only conquered nature, animate and inaminate, but has learned to use its forces, even the most hostile, in the interests of his own comfort and prosperity. Our first line of defence is, then, mental ; and the elements of time and precision are all important. We have, however, to reckon with foes far more subtle and more often mot with tlian the thunder-boU, the lion, the bear or the electric eel. In some parts of the world, the living things that can poison us are very numerous — venomous snakes, scorpions, countless insects, all ready to pour their poison and acids into our skins. Mankind has learned that alkali will neutralize their acid, and has in these latter days discovered how to manufacture an antivenin to counteract the venin or venom of the serpents. We fight chemical injuries by chemical means. But all these sources of danger or injury are insignificant compared with those which are absolutely and forever beyond the ken of our senses. In common with all other living things, we are surrounded by parasites and preyed upon by them continually. It seems a law of animate nature that any given living thing, vi?getable or animal, should have its particular parasite or parasites. For even the vegetables have parasites: the potato has the potato-blight, a fungus; the vine has its phylloxera, another fungus, and so on. The lower plants prey on the higher, the higher on the highest. Fungi and moulds are parasites on both plants and animals. Animals are parasitic on plants: grubs eat the roots and the buds of fiowers, the aphides destroy the roses, the Colorado beetle devours the potato. The gooseberry moth strips the leaves off the goose- berry plant ; the oak has its galls, everything its blemishes. To sucli an extent is all this recognized now-a-days that a department of botany, economic vegetable parasitolog}', has arisen within the last few yeard. Expert botanists are studying the conditions under which these pests HOW WE DEFESD OVRSEl. VES FROM OVU FOES 95 aip|>car nnil thcrrfnrc liow we may titliiT (ruard our flowers and food- vcp'tnlilcM friiin tlii'ir ravuRi'a, or remove the iiiira«ite< when onie tliiy Imvc ^itlloil on their vitlims. Tlie lo*» to funiur.-, fruil-growere and liiirlicultiiriits caili vi.. 'iroiigli |inra«iti» U enornioun. Fun;:! ami triduMs nre jiar-- itie .in aniimil« as nell an on veitetoWea; llie salmon has the fiinRiiicl salmon ilisease, the (fmuse has the haclerial gronse ilisease, tl)o harn-door foivl lias its cholera, the swine have swine-fever, the cattle hare anthra.v and ITinderiK'st, horses "glanders" and so on. Then animal [larasites infest animals; the frog's lung harliora cer- tain lowly ercuti.res known as (iregarinida;; dogs, cats, pigs, liorses, fill have their intestinal parasites, from which ohnoxious worms man himself is hy no means exemjit. Host and unhidden guest, victim and parasite— this inter-relation- ship runs through the wl ole of living nature; it is not the exception, It is the rule, Nature has-indeed provided for it; the intestinal worms of the horse have actually devc'-ped an and'-fcrmcnt which prevents tlieir lieing digested by the digestive ferments of the horse's intestine. Attack and defence, action and reaction unceasingly, this is nature's method ; there is no rest ; and there is no splendid isolation ; we must be attacked and preyed upon and resist — forever! A few plants and animals have taken refuge in "protective mim- icry"; the dead-nettle imitates its slinging neighlior, and so is avoided by such animals as avoid the latter; some insects imitate dead leaves, twigs, etc., and so are not devoured by insect-eating birds. But the majority of the foes that man has to bailie with are far more subtle than intestinal worms or mosquitoes, or even ''ingi; for there are myriads of bacteria so lipM that they float iii air even when dust settles; so small that Trillions can miiabit a drop of water; so numerous that arithmetic is powerless in designating them ; so power- ful that they have emptied cities, decimated armies and devasted con- tinents. The mortality of the great Boer War had been a trifling thing if the English had had only to reckon with the Mauser bullets ; far more deadly the typhoid bai Hi than all the guns of all the Dutchmen and their allies. It is now common knowledge that nine out of ten seases have an actual, physical recognizable source or cause ir, some particular parasitic bacillus (rod-like form) or coccus (round form). Undoubtedly some diseases are due to microscopic animal forms, such js ague (malaria), yellow fever, dysentery, the sleeping sickness ; but ' ,ast majority are due to vegetable parasites of microscopic size. Au those serious dis- eases known as diphtheria, typhoid fever, cholera, plague, tuberculosis, pneumonia, influjnza, rheumatism, common cold, and infantile paraly- sis, have been 'hown to be due '.o the living body heinc invaded by countless numbers of infinitely minute rod like or ball-like uiicrobes. THE POPULAR SCIENCE MONTHLY Of wiirw oil hncteria are not dincaso-bringins (pathogenic) ; and it is wult for U9 tliat it i* en, for ttm air, uartK ami water teem with bactt-ria of Home Kort. Miiny are quite harniteH and arc occupied only witJi pftting rid of dead IwHliea \\y {)utrefaftivc fermentation. But our preM'nt concern ia with our inviitiblc foes, and we must now try tti find out liow our lK)diei4 protect tlieniH-tves against their presence and their jHiiiioninga. We liQvc three cliief mcthodi whereby we defend ourselves from our invi^iltte focit, namely, the physical, tlie vital or protoplasmic and the chemical. We possess as an outermont line of defence the intact slcin and mucous mcnihranes, the horny layer (keratin) of the skin and the mufus-covered layer on the internal surfaces being impenetrable by micro-organisms. The living colony — the entire animal — is surrounded by armor, the body is nrmor-plato