v-1 



H 23,. i 



VOL. LV.— Xo. 3.047 



SATUEDAY, MAECH 23, 1912 



1 1 



THE 



GARDENERS 



9 



MAGAZINE 



'4'. % 



iter. 



rt(nven. 

 C dialog '■ 



NOTE OF THE WEEK^ 



4 



tainii 



>n, E,t 



Symbiosis. 



Tlie term symbiosis has been applied to 

 those very peculiar associations which have 

 been found to exist both in the animal 

 kingdom and that of plants, in which a 



are often unwelcomely plentiful in our 

 gardens^ and most of us know tliat a sort 

 of symbiosis exists between them and the 

 aphis, or green-fly, which exudes a sweet 

 and honey-like liquid, that the ants 

 greedily devour, and obtain by gently strok- 

 ing the aphis w^th their antennie. The 

 symbiosis, however, which we have in mind 



thus treated, have by a process of evolu- 

 tion become so nuxlifietl in character that 

 it is often a matter of great difficulty for 

 e\en the expert entomologist to determine 

 to wluit outside order or genus they really 

 belong, and from which they originatt'd,and, 

 in point of fact, tlie 



great number of 

 s})ecies we have mentioned are practically 



of known genera, but 



new species 



and 



sort of friendly alliance has been entered goes much farther than this, the guest 



into for mutual benefit, thus differentiating insects, as they are termed, inhabiting the often, quite extraordinarily different' from 

 such associations from parasitical ones, in 

 which the benefit is entirely one-sided. In 



item the plant world the association 



is usually on a microscopic 

 scale, with bacteria, which of 

 late years we have learned do 

 an immense amount of 



nests of the ants and termites, and being any of the independent living ones. Beetles 

 fed by them for the sake of sweet juices !)f inimermis species appear to predominate, 



and manv of these, as of the 



ned. 



anting 



h. 9,'- 1' 



316 k 



good 



by their association, tenanting 

 P^*^'^^ the roots of the host plants, 



and assisting them by produc- 

 ing nitrogenous nutriment by 



1 doz. which the plants benefit, 



while, on the other hand, the 



bacteria themselves find a con- 

 genial habitat and nutriment 

 for their needs in the roots 

 they occupy 



of this fact has enabled the 

 orchidist particularly to raise 

 plants from seed which 

 hitherto had often been a 

 matter of great difficulty. 

 Ou r scientists , however, by 

 ca ref nl examination of the 

 soils in which orchids thrive, 

 discovered that special species 



of micro-organisms, 

 teria 



Vr 



l-r 



A kno\\iedge 



24 



it, 



pplicit 



STE 



or 



bac- 



people the soil in such 

 f< cases, different species accom- 

 panying, symbiotically, differ- 

 t^nt species of orchids. The 

 I'ext results obtained by care- 

 fully conducte<l experiments 

 ^vith special cultures of these 

 bacteria were, that orchid 

 seeds sown on sterilised m.ate- 

 iial either failed entirely to 

 ^tM-minate, or did so so feeblv 



other kinds of insects, have so 

 responded to the requirements 

 of their '^hosts'' that they 

 ha ve de ve] oped br : ghtly- 

 coloured brushes and other ap- 

 l)ondages, whence the 

 cluii'ine juices exude 



sac- 

 for the 



benefit of 

 their 



the hosts, 

 have become 



while 

 also 



jaws 



fittingly shaped for receiving 

 their foo<l from the ants and 



They 



in other 



termites 



ha^ 



•e 



ways ; 



m return, 

 also varied 



quite 



un-ant like 



species have actually become 

 so like the ants themselves as 

 to deceive all but experts. 

 Among the tropical wandering 

 ants, which periodically tra- 

 verse the coiuitry on devastat- 

 ing expeditions, in the course 



of which 



nothing 



living 



escapes them, some actually 

 convey their guests with them, 



some on foot, and others are 

 carried by means of special ar- 

 rangements which have bee] 

 evolved to meet the ca^e and 



facilitate 



their 



transport- 



guest msects 

 ials by the 



2. 



ME. H. GOIJDE. 



Some of the * 

 are treated as 

 ants, instead of providers of 

 a[)pr('( iate(l juices, and in that 

 case assist in what we may 

 term the domestic offices of the 



0^ 



as to perish soon afterwards, while, if sown w Inch they exude. The most remarkable ant colony. In any rase, liowever, we have 

 f>n material provided by these cultures with feature here is the enormous number and here a multitutle of most remarkable cases 

 the proper kind of bacteria, irermination the varied character of the insects con- of true svmbiosis. in the sense of amicable 



^vas vigorous, as was also subsequent 

 fiiowtb. This, of course, proved conclu- 

 tnely the beneficial symbiotic action of th 



0 



»i^cteria concerned, and also cleared up the 

 mystery that orchid seeds, which resisted 

 ordmary sowing, often apj^eared in quan- 

 tities around the parent plants, where, o 

 ^'*>;irse, the necessary bacteria occupied the 



is, however, perhaps in the rela- 

 t'ons between insects and insects, and par- 

 ticularly with ants and termites (the white, 

 ^>-^-alled, ants), that the most astonishing 

 ^'»t^M relations exist. " 



^'ith the common species of ants which 



<-erned, it having been estimated that some- 

 thing like 3,000 different species of sucli, 



py the nests of the 



^^oil. It 



guests exist, and 



great numbor of ants and termites known 

 all over the world. All these guests " be- 

 long to insect orders, most of the members 

 f of which lead independent lives, but some, 

 and as we have seen not a few, have, in 

 some inscrukible way, come into asstx iation 

 with their " hosts,^' who. instead of de- 



;ind mutually beneficial association between 

 ilivt'rse forms of insect life, the study of 

 which undoubtedly j)lace the ants and ter- 

 mites on a very high mental plane, if w© 

 mav use such a term in connection with 



Mr' 



mere insects. 



We are all familiar 



stroying them as intruders, have permitted 

 them to remain, and, in most cases, i>ro- 

 vide them with food, profiting in return 

 by the juices aforesaid. These insects, 



Mr. H. Goude, whose portrait we 



have the pleas'ire of gii'ifg in this issue, 

 is busily engaged in disseminating a know- 

 ledge of horticulture in the county of Nor- 

 folk : and. judging from the results cb- 

 tainetl, he affords a conclusive proof of the 

 enormous advantage to a teacher of gar- 



