December 9, 1920] 



NATURE 



463 



of that series. Dr. Newell .^rber, who supplied 

 the original impulse for this work, laid the founda- 

 tion for the author's position in this respect, and 

 Miss Sarjjant's derivation of the Monocotyledons 

 from the primitive Ranalean plexus is here 

 accepted. 



An explanation of the great structural reductions 

 ivolved in the transition from terrestrial to aqua- 

 ■ life, and in the transference by hypothesis of 



■ I many families from the beginning to the end 

 : the series of the .Vrchichlamydeae, became a 



..rcessity; so the author proposed her "Law of 



Loss," which has proved to be related closely to 



Dollo's "Law of Irreversibility" for animals. This 



rt-sts on the principle that what is lost in the 



'jurse of plant evolution can never be regained, 



ad, if required again, "must be constructed 



fresh in some different mode." From this point 



: view the leaf-blades of several aquatic plants 



■ ould be regarded as expansions of the petioles, 

 ■i.l much light would be thrown on the many 



(Ikult questions involved in the interpretation of 



II- flowers. 



The author's position regarding natural sclec- 

 iKin is discussed, so far as it is determined by 

 :if|uatic plants. The principle is almost protean 



: its appearances. When we think we have dis- 



,-i)sed of it in one shape, it arises in another. If, 



like Dr. Willis, we exclude it in the case of 



ho genera and species of the Podostemaccae, it 



rns up again as the principal factor in the 



laptation of the group for life in rapid waters. 

 >r. .\gnes Arber shares with many others her 



ilicullies in accepting whole-heartedly the prin- 

 < iple May it not be possible to assume that 

 ihcse difficulties would disappear if wc broadened 

 (lie basis of the theory? Whilst supporting 

 Darwin through so many years. Hooker was hold- 

 nij a view of divergence, under the name of 



entrifugal variation" (really a conception of 

 iffcrentiation), that was directly opposed to im- 



•rtant points of the theory. Yet he considered 



•It the greiitcst hope of the investigator lay in 

 ill- general lines marked out by Darwin. 



However that may be, we are reminded by the 



ithor of this book of an evolutionary idea, both 

 !'i and new, that is capable of great develop- 



<-nt. The principle that what organisms gain 

 111 specialisation they lose in plasticity presents us 

 with quite another way of viewing evolution — a 

 view in which progression offers itself as a suc- 

 cession of lost opportunities. Progress in one 

 direction involves the closing of the gates in 

 "countless other directions," the possibilities of 

 choice ever narrowing as wc go up the scale. It 

 is suggested that this would be impossible but for 

 NO. 266;, VOL. 106] 



the inheritance of acquired characters, bound up, 

 probably, with the inheritance of unconscious 

 memory. At all events, it presupposes a 

 primeval era of plasticity in whieh heredity had 

 but little power. The line of thought is similar 

 to that followed by Beccari in his theory of 

 plasmation. Here a long vista opens up, and at 

 its distant end lie the problems connected with 

 the origin of the great groups of the plant world. 



H. B. Gi'ppv. 



The Behaviour of Beetles. 



The Glow-worm and other Beetles. By J. Henri 

 Fabre. Translated by Alexander Teixeira dc 

 Mattos. Pp. viii-t-488. (London: Hodder and 

 Stoughton, Ltd., 1919.) Price 8s. 6d. net. 



THIS is the second volume on beetles in the 

 complete English edition of <lenri Fabre's 

 entomological works. The first essay, "The 

 Glow-worm," which gives its name to the book, 

 did not form part of the " Souvenirs Entomo- 

 logiques," but was written for translation into 

 English towards the close of the veteran natural- 

 ist's life. Several chapters, like this first one, 

 have already seen the light in English, but most 

 of the book is fresh, and it is very convenient to 

 have the studies on beetles brought together. 

 Eventually there will be four volumes on beetles. 

 The experienced translator, Mr. Alexander 

 Teixeira de Mattos, has done his work with great 

 skill. 



These arc wonderful stories. The glow-worm 

 tweaks a snail with its sharp mandibles, and ad- 

 ministers an anaesthetic; a number of other glow- 

 worms hasten to the repajst and fall to; the flesh 

 is converted by exuded ferment into a sort of 

 gruel, and the fluid is sucked up by the hollow 

 jaws. Wc suspdct that there is some inaccuracy 

 in Fabre's account ; it seems clear, for instance, 

 that the fluid food enters the gullet by the mouth, 

 and not via the mandibles. In any case, Fabrc » 

 observations must be compared with those of 

 Bugnion and Miss Kathleen Haddon. In regard 

 to the luminescence Fabrc was cautious : — 



"From start to finish, the glow-worm's life is 

 one great i>rgy of light. The eggs are luminous; 

 the grubs likewise. The full-grown females arc 

 magnificent light-houses, the adult males retain 

 the glimmer which the grubs already possessed. . 

 Wc can understand the object of the feminine 

 beacon; but of what use is all the rest of the 

 pyrotechnic display? To my great regret, I cannot 

 tell. It is and will be, for many a day to come, 

 perhaps for all time, the secret of animal physics, 

 which is deeper than the physics of the books." 



