July 9, 1891] 



NATURE 



219 



There is not space enough to do more than allude to 

 the sawflies, another class of insects fearfully injurious 

 to trees of divers kinds. Many of these Hymenoptera, 

 as in Great Britain and other European countries, 

 mainly of the genus Nematus, clear off the leaves of 

 forest and fruit trees. Others attack firs, notably some 

 species of Lophyrus and Lyda, as the Lophyrus abietts, 

 Lophyrus pinetutn, and Lophyrus pini-rigidce, and some 

 of the Lyda. Cameron, in his monograph of the British 

 phytophagous Hymenoptera, states that there are fifteen 

 species of Lophyrus in North America, and that the 

 species of Lyda are common there. 



Lophyrus abietis and Lophyrus abbotii appear to do 

 the same harm in America to firs as the Lophyrus pint 

 in Scottish fir plantations, whose larvae not only eat the 

 leaves but the bark of the young shoots, frequently occa- 

 sioning great losses. 



An instructive account is given in this work of the effect 

 of temperature upon insects. It is the fashion in Great 

 Britain to say that insects are killed by hard frosts. But 

 they are not killed in countries — as America, for example — 

 whose winters are far more severe. Dr. Packard, quoting 

 JudeichandNaitsche's"LehrbuchderMittel-Europaischen 

 Forstinsektenkunde," observes that " the influence of even 

 very great cold on the normal hybernating stages of our 

 insects is not very great. In the summer of 1854 the 

 ' nun ' moth had very generally laid its eggs in Eastern 

 Prussia uncovered on the bark, and these did not freeze 

 in the hard winter of 1854-55. According to the ob- 

 servations of Regener, openly exposed caterpillars of the 

 pine silk-worm endured lo" F. The pupa froze at 21^ F., 

 the moth at 19" F. According to Duclaux, the eggs of the 

 silk-worm endure well, remaining two months in a tem- 

 perature of 17° F. Great fluctuations of temperature 

 during the winter produce an abnormal interruption of 

 the winter's rest or hibernation, and thus cause the death 

 of many insects." It will be noticed that in all these 

 cases the insects were unprotected, whereas there is 

 generally some kind of protection during the winter for 

 insects in all stages, provided by their instinct. 



Not the least useful part of the Report is that treating 

 of remedies for insect attacks, and machines and engines 

 for applying them. Arsenical poisons, known as Paris 

 Green and London Purple, are strongly recommended for 

 spraying or syringing trees infested with the larvae of 

 beetles and sawflies, or the caterpillars of moths. These 

 have been recently introduced into England, being advo- 

 cated by the Board of Agriculture, but have not been 

 extensively adopted yet, owing to the natural prejudice 

 against the use of poisons. In America they are em- 

 ployed most extensively and with the greatest benefit. By 

 means of these the potato beetle {Doryphora decern- 

 lineata) was circumvented, and the cotton and boll worms 

 checked, and the onslaughts of many other insects ma- 

 terially lessened. For Aphides, Scale insects, and other 

 insects which suck the sap of leaves, "emulsions" or 

 washes of soft soap, or "jelly soaps," made directly from 

 fish oil and concentrated lye, or whale-oil soap, are pre- 

 scribed. Also kerosine, naphtha, and petroleum, applied 

 in a fine spray, or mixed with soap and soap jelly, forming 

 "emulsions." These remedies act by contact, being 

 applied principally to insects which do not eat the leaves^ 

 as well as by making the surroundings unpleasant and 

 NO. I 132, VOL. 44] 



unbearable. Powdered substances, as pyrethrum, helle- 

 bore, and sulphur, are not much employed for forest work, 

 but cases frequently arise warranting their use in a limited 

 way. Hellebore, as gooseberry growers in Kent and 

 Cambridgeshire well know, is of especial value against 

 all sawfly larvae. Sulphur is valuable against the red 

 spider {Tetranychus telarius), and is used alone or in 

 connection with emulsions of kerosene. 



Numerous machines are in vogue for putting on washes 

 and powders, from the small "knapsack" machine carried 

 on the back, to huge tanks on wheels, fitted with power- 

 ful hand-pumps and long lengths of hose, through which 

 liquids are forced to great heights ; for very high trees, tall 

 ladders are used, which are set near the trees, upon which 

 men mount, and direct the hose into the topmost branches. 

 For smaller trees and shrubs, a barrel fixed on wheels, 

 having a good force-pump with hose, is adopted. Pumps 

 are also fitted into tanks of all shapes and sizes, and 

 moved from place to place by hand or horse-power. To 

 distribute the liquids there are endless nozzles or jets 

 contrived with much ingenuity to send forth fine mists, 

 or sprays, or continuous volumes. It will suffice to say 

 that the best of these is the cyclone, or Riley nozzle, 

 which is just being introduced into Great Britain. 



Foresters, and all concerned in the management of 

 woods and forests, public parks, and gardens, would do 

 well to consult this work for information as to the various 

 insect enemies of trees, and the best means of dealing 

 with them. It is quite impossible in a review to give 

 anything more than a general idea of its scope and 

 nature. 



PHYSICAL RELIGION. 

 Physical Religion. The Gifford Lectures delivered before 

 the University of Glasgow in 1890. By F. Max Miiller. 

 (London: Longmans, 1891.) 



THE present volume, which embodies the author's 

 second course of Gifford Lectures, with notes and 

 appendices, is devoted to the consideration of " Physical 

 Religion," that is the religion which finds its object the 

 Infinite in or behind the phenomena of Nature. The 

 author's previous writings have made it clear that for the 

 simplest and most abundant manifestation of this form 

 of religion we must go to the Veda, so his first task in 

 the lectures before us is to tell once more the familiar 

 story of the discovery, the character, and the age of the 

 Veda. To this survey four lectures are devoted, and, in 

 conclusion, the author — not without duly considering all 

 that in recent years has been urged to the contrary-^-re- 

 affirms his conviction that the hymns of the Rig Veda 

 cannot have been collected later than 1000 li.c. 



In the sixth lecture the author deals with the evolution 

 of the idea of God. It is often supposed-— even by philo- 

 sophers of repute — to be a sufficient account of the 

 earliest form of religion to say that men worshipped 

 stones and other fetishes as their gods. But, as the pro- 

 fessor well remarks — 



" Does it never strike these theorizers that the whole 

 secret of the origin of religion lies in that predicate, their 

 gods? Where did the human mind find that concept 

 and that name ? That is the problem which has to be 

 solved ; everything else is mere child's play." 



