202 



KNOWLEDGE. 



[September 1, 1897. 



Eyland, preen peas, broad beans, and sweet peas (especially 

 the last) benefited by inoculation ; French beans were 

 doubtful. At Messrs. Sutton & Sons' nearly the whole 

 of the experiments gave favourable indications, especially 

 as regards root growth. Wheat has been grown this year 

 at Messrs. Sutton's on the ground used for these experi- 

 ments, and it will be interesting to see what improvement, 

 if any, has been effected. 



By the light of present experience, it is necessary to take 

 the following prt cautions when using the new inoculating 

 material : the ground must either be inoculated before 

 sowing, or the seed itself must be inoculated, and the 

 organisms sown with the seed. This is important, as the 

 nodules are formed in the early stages of the growth of the 

 plant. As the inoculation only assists the plant to obtain 

 the nitrogenous portion of its food, other manures, such 

 as phosphates and potash, must be supplied, just as in the 

 ordinary way. Where a particular crop — say, of beans — is 

 doing Well, it is foolish to expect to improve matters still 

 more by introducing the new material, as it is quite clear 

 that the soil is already inoculated. Further and more 

 elaborate experiments with " nitragin " are being con- 

 ducted this year, and we hope they will lead to definite 

 rules of conduct being laid down. 



One of the most hopeful applications of the new inocu- 

 lating material is in conneciion with " clover sickness." 

 It is found in practice that clover can only be grown for a 

 comparatively short time on a particular piece of land ; the 

 soil then becomes " clover sick," and about eight years 

 must elapse before the field can be sown again with clover 

 successfully. The reason for this is unknown, but it may 

 be due to the exhaustion of the organisms that live on the 

 roots, without which the plant cannot thrive. If this be 

 the case, the application of fresh inoculating material will 

 enable the farmer to grow clover every year, if he desires 

 it, off the same plot. 



The knowledge of these organisms throws a light on the 

 fact that, as every gardener knows, manure alone, how- 

 ever well proportioned, is not sufficient for the satisfactory 

 growth ot most plants ; it is necessary to have a large 

 quantity of decayed vegetable matter present as well. An 

 old garden that has been well looked after produces far 

 better crops than one newly planted, the difference being 

 due in all probability to the quantity of these useful 

 organisms present in the old vegetable soil. 



Important as the discovery of root organisms may, and 

 probably will, be to agriculture, the application seem^ 

 small compared to the immense possibilities that are opened 

 up in the region of chemical industry. On the one hand 

 we have this inert nitrogen of the air, that can only be 

 made to combine with other elements under the stress of 

 the greatest force at the command of chemistry and pbysics, 

 viz., the electric arc ; on the other hand, these tiny 

 organisms are making nitrogen enter into combination at 

 the ordinary temperature of the soil. W^hen the secret 

 of these organisms has been mastered, we shall have 

 drawn much closer to the boundary that separates gods 

 and men. 



FAIRY FLIES. 



By Fred. Exock, F.L.S., F.E.S. 



IF it were possible to obtain a reply from all living 

 naturalists as to what first attracted their attention 

 to insect life, I venture to think that seventy-five per 

 cent, or more of the replies would be: " The first 

 sight of a living butterfly." How many (f us (no 

 matter what our speciality may now be) can look back to 

 that time when, perhaps, a tortoiseshell flaunted its beauty 



before our youthful eyes, and we were drawn to it and 

 fascinated by its gorgeous colour, as it delicately sipped 

 the nectar from a dandelion or thistle, gently opening and 

 shutting its wings, spreading them as wide as possible so 

 that every part should be seen ! The colours and markings 

 flashed before our enraptured gaze, and while we were held 

 captive by its beauty, another still more beautiful butterfly 

 — the peacock —sailed past and alighted close to the first, 

 rivetting our attention by the marvellously lovely " eyes " 

 on its wings; and again another — this time a red admiral — 

 in full sail bore down upon us, opened fire, and we surren- 

 dered, swearing allegiance for evermore to Atalauta and 

 all her crew. Few boys could stand still and not be affected 

 or influenced by such beauty. Such then has been, and 

 will be, the foundation of our naturalists — " butterfly 

 hunters " first, specialists later on. 



My recollections carry me back a long way, to the time 

 when, in passing a cobbler's shop, I saw some cases of 

 insects hanging against the wall. They very soon attracted 

 me, and many delightful hours did I spend sitting close to 

 " Daddy Lucas " listening to the wonderful accounts of 

 how he caught his butterflies and moths. Since those 

 delightful years of childhood I have noticed that —from 

 butterflies and moths — a few schoolboys collect beetles 

 and dragon flies ; but Diptera and Hymenoptera are not 

 collected. Blowflies belong to the first, and bees and wasps 

 to the second, and both sting, and so are left alone except 

 when a nest is discovered ; then boys do collect together, 

 to join in the attraction of danger, the marvellous structure 

 of the nest being knocked to pieces with as little com- 

 punction as a palace in lime of war. 



The insects included in the class Hymenoptera are of 

 vast extent and variety, comprising many of the most 

 beneficial, as well as some of the most destructive, to all 

 crops. Among the latter may be mentioned the goose- 

 berry sawfly, which at certain seasons denudes the bushes 

 of every vestige of green leaf; but this pest can be much 

 lessened and got rid of if preventive measures be taken in 

 good time, instead of stupidly allowing the damage to go 

 on before one's eyes. There is no easier or more efl'ectual 

 method fur destroying the-ie grubs than that of opening an 

 umbrella, turning it upside down, and holding it under- 

 neath the bushes, the branches of which should be gently 

 tapped, when the grubs will fall down into the open 

 umbrella ; hundreds and thousands may be caught in a 

 very short time — and all turned into a vessel of boiling 

 water. Delay this easy remedy, and the grubs become 

 full fed, then burrow below ground, where they spin small 

 earth-coloured cocoons, in which they change to pupse — a 

 future harvest for evil. The turnip sawfly grub or 

 " nigger " might be, and ought to be, looked after, and its 

 numbers could easily be lessened were systematic and 

 combined measures taken ; but until such happy times 

 both gooseberry and turnip sawflies will go on sawing. 

 How many of the merry wearers of the oak-apples on 

 May 29th — " Royal Oak Day " — know or ever think what 

 forms the "apples" or " oak-'taters " (Worcestershire)? 

 Few imagine that a small hymenopterous insect is the 

 founder of these wonderful " galls " ; but so it is, and 

 the C)cle of the life history of a single oak-apple and its 

 contents would astonish anyone. To another insect 

 belonging to the Hymenoptera there is not a single man, 

 woman, or child who does not owe a debt of gratitude 

 for the incalculable blessing of ink, which is manufac- 

 tured from the oak-gall found in Turkey. This gall is 

 gathered before the fly has escaped, so that it is what may 

 be termed of " full flavour " and " bitter as gall." 



Following the gallflies, we may turn to the Iclineumonida 

 —a large family to which lepidopterists often bear a 



