132 



NATURE 



\yune 13, 1872 



plants, and on the general aspect of the whole vegetation they 

 constitute {Vi'gt'lalioitsfunnen and Ve«-ciii//'ons/ormntio>ie>i), v/ilh 

 the same] high estimate, or we might say over-estimate, of its 

 effects on the typical character of the species as compared with 

 the complicated consequences of previous possession, foreign in- 

 vasions, and natural selection in the struggle for life, which he 

 seems disposed to ignore, and with the same a'lusions to certain 

 mysterious creitive or productive forces heyoinl the reach of our 

 inquiries. A closer examination of his regions show them to b; 

 much better conceived in his phyto-clirnatic point of view, than I 

 had at first thought them to be when regarded as phyto-geogra- 

 phical regions ; and although further explorations may cause 

 him to modify their limits in several instances, yet, in regard to 

 all of them, the data he has collected and methodised will be 

 foufifl to be an important contribution to the scientific study of 

 geographical distribution, the value of which is enhanced l>y 

 copious references to the sources whence he has derived his in- 

 formation. 



There are two gener.al subjects upon which the bulky mass of 

 literature continues to receive considerable accessions, both in 

 this country and on the Continent, without perhaps adding much 

 to our stock of information, and which would at any rate re- 

 quire long and patient study to extract what miy be really of 

 value ; these are Darwinism and so-called Spontaneous Genera- 

 tion. Darwinism in some shape or other, or something under 

 that name, enters more or less into almost all general discussions 

 on points of natural history, especially on the Continent, and in 

 so far as it is applicable to what .-the Germans call the Dc.'- 

 sceihic}iztheorii; it is being more or less tacitly adopted by the 

 great majority of naturalists ; but in a general way, the compre- 

 hensive hypotheses propounded by Darwin in his various work- 

 are still the subject of much polemical discussion. Seidlilz, in 

 his work entitled " Die Darwinsche Theorie," fills thirty pi',;es 

 with the mere titles of the works, memoirs, or papers pul)Ushed 

 on the subject since 1S59, and to this enumeration many addi- 

 tions might be made. Amidst this great mass it might have 

 been expected that I should have selected some lobringspecially 

 under your notice — that I should h.ave followel up the observa- 

 tions 1 made on the " Origin of Sjiec'es " in my address of 1S63, 

 and on the " Variation of Animals an! Plants under D jmes- 

 ticity" in that of 1S6S, by some notice of the "Descent of 

 Man," as well as of some recent works of other writers, such as 

 Mivart's "Genesis of Species;" but these have been alrcaly 

 fully discussed by natur.diits much more competent than a p irely 

 systematic botanist to deal with the question in the pha;e wliicli 

 it has now reached, and I have not met with any other work in 

 which any connected series of observation^ has been methodised 

 and brought to bear more directly on the general life-history of 

 animals and plants. The detached observations upon Several 

 points connected with D vrwin's general theories, especially those 

 relating to dichogamy and cross fertilisition in plints, continue 

 to be very numerous, as well as the endeavours to connect recent 

 with geologically ancient races of both animals and p'ants, 

 without, however, making any one move of importance towards 

 the solution of the probletns before us ; and we are still 

 anxiously awaiting from Mr. Dar^tin himself that long-promised 

 second portion of his great digest which is to treat of Che varia- 

 tions of undomesticited animals and plants. 



Spontaneous Generation has perhaps been of late the subject 

 of more controversy in this country thin abroad. Since Prof 

 Huxley, followed by Prof. Tyndall, placed the matter in so clear 

 a light at the Liverpool meeting of 1S70, Dr. Bastian has re- 

 turned to the charge. In his work entitled " The Modes of 

 Origin of Lowest Organisms," he has published an account of 

 numerous experim nts further illustrating his views in opposition 

 to those of lluxley and Tyndall, and confirming, in his m:nd, 

 the theory of Archebiosis, the name he gives to what is com- 

 monly called Spontaneous Generation. On the other hand, Mr. 

 N. Hartley has comnuinicatcd to the Royal Society ("Proceed- 

 ings," xx. No. 132) his experiments conctrning the evolution of 

 life from lifeless nutter, which appear to has'e been conducted 

 with great care, and in some measure under the guidance of Dr. 

 Odiing and Prof. Tyndall. From these he concludes that so far 

 as our present knowledge guides us, whether we term it Spon- 

 taneous Generation, Abiogenesis, or Archebiosis, the process by 

 which living things spring from lifeless matter must be said to be 

 only ideal. The same numSer of these "Proceedings" contains 

 abstracts of papers by Dr. Grace Calvert on the development of 

 protopla-mic life, its influence on putrefaction, and the effect of 

 various substances in promoting or arresting its progress, all of 



which papers are connected with, and in continuation of, his 

 former experiments and conclusions tending to support the theory 

 that this protoplasmic life is derived from invisible germs floating 

 in the atmosphere. Dr. Bastian, at a later meeting of the Royal 

 Society, again returned to the subject in a paper entitled "On 

 some llelerogenetic Modes of Origin of FlagclUted Monads, 

 fungus.germs, and Ciliated Infusoria," inserteci at length in No. 

 133 of the " Proceedings." The ctperimenls an 1 observations 

 here detaded are very interesting as to the development of these 

 organisms in the pellicle that forms on infusions of organic matter 

 '.vhen exposed to the atmosphere ; but they do no: affect the 

 question of the origin of the living components of the pellicle 

 itself, which he considers to have been fully proved by his own 

 former papers, as well as by the well-known experiments of 

 Pouchet and others, to have been evolved from lifeless matter by 

 archebiosis A more extended work, giving the fullest details of 

 his views of the " Beginnings of Life" is announced, but I have 

 not yet seen it. 



If, then. Spontaneous Generation may as a theory in the minds 

 of some persons have become referrerl to the class of paradoxes 

 like the quadrature of the circle, yet it is still supported by so 

 many naturalists whose opinions are entitled to consideration, and 

 there is so much to be said for as well as against it which appears 

 unsusceptible of direct and positive proof, that it ii likely to bi 

 long maintained as a subject of controversy, without any further 

 much more definite result. But there is one question of a more 

 practical nature, often supposed to be connected with it, which 

 has excited, and is still calling for the serious attention of men 

 of science, experience, and judgment, as well as of various 

 Governments. I allude to those parasitical scourges which with- 

 in the last thirty years have made su^h havoc in several important 

 articles of Europem food an 1 indu-try. Thirty years since, and 

 I believe up to the fatal year 1845, the potato-diicase, the silk- 

 wjrm-pebrine, and the oidium of the vine were unknown in 

 Europe ; and we can most of us remember how the sudden 

 appearance and rapid extension of each in succession produced 

 the famine in Ireland, ani the ruin of so many French and 

 Italian silk-breeders and wine-growers of the Mediterranean 

 region, Madeira, and Bordeaux ; and ho v for long men of science 

 have been baffled in their efforts at as:ert lining the true history 

 of the attendant fungi, and devising an efficacious remedy. The 

 p jtato-disease appears now to have settled down into one of those 

 chronic epidemics whose varying intensity, according to season 

 and other circumstances over which we have little control, must 

 enter into the calculations of every potato-grower. This useful 

 tuber can no longer, indeed, be advantage ludy cultivated in that 

 wholesale manner which induced the late Thomas Andrew Knight 

 and others to attach to it so high an ejonj.mic value, but it 

 may now again be fairly depended upon as an important article 

 of household food. 



The pebrine of the silkworm, from the latest reports I 

 have seen of the Commissions of Lyons and other places, 

 shows but little abatement of its intensity, although it it has 

 in some measure changed its character, and is, it is to be 

 feared, through the carelessness or cupidity of interested dealers, 

 spreading even into those eastern regions which have been looked 

 to for the supply of "seed" free from the fatal germ. The 

 oidium, on the contrary, has been got more under control ; and 

 experience now shows that in many districts at least its ravages 

 can be checked or entirely stopped by means within the reach of 

 every intelligent cultivator. But within the last few years a new 

 plague has in the south of France excited even more alarm than 

 the oidium itself, from its insidious invasion and complete de- 

 struction of many of the most valuable vineyards ; this time, how- 

 ever, the offending parasite is brought much more within the scope 

 of direct scientific observation. The germs of the potato-fungus, 

 of the pebrine, of the oidium, are all invisible and inappreciable 

 by any of our instruments ; the history of their ditfusion and 

 early development, and even their very exis'ence, can only be 

 juilged of from their results and other c rcumstantial evidence ; 

 whilst the Phylloxera -uistalrix can be watched in every stage of 

 its varied existence, from the first deposit of the fertilised eggs, 

 through its several agamic generations, to the latest winged form. 

 The researches, accordingly, which have been already applied to 

 it have not been altogether barren of results, throwing some light 

 even generally upon the origin and dispersion of these pests. 

 Considerable sums of mon.ey, either from the French Govern- 

 ment or from private subscriptions, have been applied to the 

 purpose, and the investigation has been chielly carried on by our 

 foreign member, Dr. J. E. Planchon, of Montpellier, assisted by 



