448 



NA TURE 



\_March 1 1, 1880 



and from Pasteur, C\hn, and others we know of diseases 

 due to those simplest of fungi, the Bacteria, which 

 produce the most deadly ravages amongst insects. Prof. 

 Metschnikoff has examined some of these minute parasitic 

 fungi and cultivated them by passing them from one 

 insect to another, and has experimentally proved their 

 very deadly character to the insects exposed to infection. 

 The "green Muscardine " (Isaria desttttctor) is the name 

 given by Metschnikoff to one of the minute fungi the 

 effects of which he most successfully traced. Now it is 

 perfectly evident that if green Muscardine spores could 

 be produced in large quantity, or spores of similar disease- 

 producing fungi, and applied to the ground and shrubs 

 infested by insect-pests liable to harbour those fungi, we 

 should have the best of all means for effecting the 

 destruction of the insects, viz., a poison which once set 

 at work would spontaneously multiply and spread its 

 destroying agents around. 



Accordingly Prof. Metschnikoff endeavoured tocultivate 

 the "green Muscardine"' apart from insects, so as to 

 obtain its spores if possible in great quantity, in a liquid 

 which might be applied to places attacked by injurious 

 insects. He at last succeeded in effecting this cultivation 

 by the use of beer-mash : in this decoction the green 

 Muscardine produced a rich mycelium and finally spores. 



It is exceedingly probable that we have here the true 

 explanation of the value of the application of yeast to 

 plants, &c, affected by insect pests. If there are a few 

 spores only of such parasites as the "green Muscardine" 

 about, the fluids of the yeast will serve them for nourish- 

 ment and so cause the Muscardine to spread until it comes 

 into contact with the insects. There is no reason to suppose 

 that the beer-yeast plant itself is capable of generating 

 a disease in any insects, at the same time we must 

 remember that yeast as ordinarily used by the brewer 

 is by no means pure ; it contains in small quantities other 

 minute fungi besides the Saccharomyces cerevisice, and it 

 is quite possible that a given quantity of it, say a pint, 

 may, if the brewery from which it came were not 

 conducted on the most perfect system (such as that lately 

 introduced by Pasteur), contain a few spores of such a 

 disease-producing parasite as Muscardine. A diseased 

 insect once in a way falling into the mash-tub would 

 sufficiently keep up the supply, and thus it is possible 

 that yeast may carry infection to insect-pests and destroy 

 them. 



At the same time Prof. Metschnikoff 's suggestion of a 

 deliberate cultivation of an insect's-disease-producing 

 fungus, and the application of the cultivated fungus in 

 quantity to places infested by these insects, is in the 

 highest degree ingenious and likely to give results the 

 value of which will be estimated in thousands of pounds, 

 and so do something to persuade "practical " men that all 

 science is deserving of their respect and encouragement. 

 E. Ray Lankester 



THE CLASSIFICATION OF THE ENGLISH 



TERTIARIES 

 AT the last meeting of the Geological Society of 

 ■**■ London an animated discussion took place upon the 

 question of the true correlation of the strata of the Hamp- 

 shire Basin with those of France, the Netherlands, North 

 Germany, Switzerland, and other parts of Europe. This 

 discussion was raised by a memoir read by Prof. Judd, 

 who showed that the accepted order of succession in the 

 series of fluvio-marine strata of the Isle of Wight is not 

 the true one, but that the formation in question is of much 

 greater thickness and importance than had hitherto been 

 supposed by geologists. 



These fluvio-marine strata of the Hampshire Basin, 

 which, as is well known, are quite unrepresented in the 

 London area, have attracted much attention from British 

 and foreign geologists. The order of their succession has 



been the subject of frequent controversies in the past, for, 

 like all depobits formed in deltas, the beds are inconstant 

 in character and thickness, and it is difficult to trace them 

 at the surface by the art of the geological surveyor ; 

 furthermore, the districts of the New Forest and the 

 northern half of the Isle of Wight, in which the strata in 

 question are found, are covered with thick deposits of 

 sand and gravel, so that the underlying strata are seldom 

 exposed except in sea cliffs and in such artificial openings 

 as railway-cuttings, brickyards, quarries, and wells. 



The first classification which was proposed for these 

 beds was the result of the long and careful study of the 

 geology of the Isle of Wight by Thomas Webster. He 

 believed that the fluvio-marine beds consist of a set of 

 marine strata with fresh-water deposits above and below 

 them. But the more careful study of the palaeontology of 

 the formation by Prestwich and Edward Forbes proved 

 that Webster had confounded in his " marine series " 

 several strata which are on very distinct geological 

 horizons. In the memoir now laid before the Geological 

 Society Prof. Judd carries the question one step further 

 in the same direction, and demonstrates that strata ex- 

 posed at Colwell Bay and at the base of Headon Hill are 

 not, as was hitherto supposed, upon the same horizon, 

 but that the latter underlie the former. The classification 

 now proposed for these fluvio-marine strata, which are 

 shown to have a thickness of from 800 [to 900 feet, is as 

 follows : — 



Hempstead series (marine and estuarine) ... 100 feet. 



Bembridge group (freshwater and estuarine) 300 ,, 



lirockenhur^t series (marine) 25 to 100 ,, 



Headon group (freshwater and estuarine), 



including the Headon Hill sands 400 ,, 



The Headon group is proved to be the exact repre- 

 sentative of the Zone of Cerithium concavum which has 

 been recognised at so many points upon the Continent. 



Edward Forbes's division of the " Osborne and St. 

 Helen's Series " it is shown must be abandoned, on the 

 ground that it presents no good features, either mine- 

 ralogical or pala:ontological, by which it can be distin- 

 guished, and its separation was founded on an error in 

 working out the true order of succession of the beds. On 

 the other hand, the marine strata seen about Lyndhurst 

 and Brockenhurst in the New Forest, and at Colwell Bay 

 and Whitecliff Bay in the Isle of Wight, are shown t 

 constitute a division of very great importance for which 

 the name of the Brockenhurst Scries is proposed. 



Since the date of Edward Forbes's study of these beds, 

 much new light has been thrown upon their age and 

 relations by the collection and study of the fossils which 

 they contain ; the number of species now known to us is 

 probably, at least four times as great as those with which 

 Forbes was acquainted, this result being mainly due 

 to the labours of the late Mr. Frederick Edwards and 

 other indefatigable collectors of tertiary fossils. 



1 1 is greatly to be desired that the rich stores of molluscan, 

 reptilian, and mammalian fossils, which exist in the 

 British and other museums, should be described by com- 

 petent naturalists, as much new light would thereby be 

 thrown on the life of the period when these beds were 

 deposited. 



Great difficulty has always been experienced by English 

 geologists in referring the fluvio-marine beds of the Isle 

 of Wight and the New Forest to their proper place 

 among the great divisions of the Tertiary strata. Some 

 authors place the whole of these beds in the Eocene, but 

 this can only be done by unnaturally extending upwards 

 the bounds of that division so as to include these Isle of 

 Wight strata. In the paper just read to the Society, Prof. 

 Judd shows that while the several marine Eocene faunas, 

 those namely of the Barton, the Bracklesham, and the 

 Bognor beds, are very closely related to one another, the 

 Brockenhurst fauna has but little in common with them. 

 Thus, out of nearly 200 species of marine shells found in 





