April 28, 192 1] 



NATURE 



283 



tains chain. This crust-folding was followed by the 

 deposition of plant-bearing Tertiary strata. The Raton 

 Mesa region is rich in coal-bearing beds containing 

 a large number of flowering plants, with a few twigs 

 of conifers and fragments of sterile fern-fronds. The 

 flowering plants are, unfortunately, represented almost 

 exclusively by detached leaves. 



Different views have been held on the geological 

 age of these sediments. Lesquereux referred them 

 to the Tertiary period, and later geologists regarded 

 them as Cretaceous. The evidence now brought for- 

 ward points to the occurrence of two distinct forma- 

 tions, the Vermejo formation below separated by a 

 well-marked unconformity from the overlying Raton 

 formation. It is believed that this unconformity 

 marks the boundary between the Cretaceous and Ter- 

 tiary systems in Colorado and New Mexico. In the 

 interval represented by the unconformity there was 

 widespread erosion of the uplifted floor of the Cre- 

 taceous sea before the deposition of the Lower 

 Tertiary Raton formation. 



From a gieological point of view the conclusions 

 based on a considerable mass of information are of 

 great interest as a contribution towards a more pre- 

 cise determination of the Cretaceous-Tertiary boun- 

 dary. Both the Vermejo and Raton formations are 

 rich in fossil plants, Dicotyledons being the most 

 abundant in each flora ; the Vermejo flora is 

 correlated with the Montana flora, while the Raton 

 flora is believed to be Eocene. A noteworthy 

 feature of the Raton flora is the inclusion of some 

 exceptionally fine specimens of palm-leaves, but, as 

 Mr. Knowlton states, it is impossible to refer 

 most of them t© a definite position on leaf-characters 

 only. 



The palaeobotanical portion of the volume is well 

 illustrated and the specimens are concisely described. 

 It is, however, unfortunate that little attempt is made 

 to compare the plants with species other than Ameri- 

 can. The application of the names of recent genera 

 to many of the specimens, though in accordance with 

 a common practice, suggests a lack of appreciation 

 of the difficulties of systematic work when leaves only 

 are available. In many cases it is clearlv impossible 

 to accept the generic determinations of both fern frag- 

 ments and dicotyledonous leaves without hesitation. 



Mr. Knowlton has done good service" by renderings 

 available much new material, and the excellent illus- 

 trations will enable students of palaeogeography to 

 institute comparisons between the American and other 

 types. The absence of conifers in the Raton flora as 

 contrasted with their comparative abundance in the 

 older Vermejo flora is an interesting feature, though 

 it is scarcely safe to assume, as Mr. Knowlton does, 

 that the group was unrepresented in the contemporary 

 vegetation of the district. 



The greater part of the volume is devoted to Mr. 

 Lee's extended researches, which include the results of 

 field work in many districts and a very useful correla- 

 tion of the formations in the Raton Mesa region with 

 those in other parts of the continent. 



The investigation of the later Cretaceous and 

 earlier Tertiary floras has acquired a fresh importance 

 in view of the recent work of Mrs. Reid, who is ably 

 carrying on the researches initiated by the late Mr. 

 Clement Reid on the younger Tertiary floras. The 

 recognition of many Chinese types of flowering plants 

 in the Pliocene beds of western Europe, as Mrs. Reid 

 has shown, throws light on the interrelationships of 

 floras that are now widely separated. A critical 

 analysis of the older Tertiary floras in both the Old 

 and the New World should enable us to obtain a 

 deeper insight into the early history of the Angio- 

 sperms. One of the difficulties in the way of a com- 

 prehensive survey of fossil floras is that of correla- 

 tion, and it is only by the co-operation of strati- 

 graphical geologists and palaeobotanists that this 

 difficulty can be met. American investigators have 

 realised the importance of such collaboration, and 

 their example might with advantage be followed more 

 closely in this country. It may be said that if the 

 accurate determination of fossil leaves, especially 

 those of Angiosperms, is impossible, why attempt it? 

 The answer is that palaeobotanists do not, as a* rule, 

 sufficiently avail themselves of the assistance of ex- 

 perienced systematists, and are too ready to be 

 satisfied with resemblances based upon characters 

 which are common to several recent genera. Thoygh 

 many fossil leaves referred to recent genera are value- 

 less as accurate data, this is no reason for assuming- 

 that greater accuracy in the analyses of floras is un- 

 attainable. 



Isle of Wight Disease in Hive Bees.^ 

 Bv Dr. a. D. Imms. 



T SLE OF WIGHT disease is the most serious 

 ■*• menace to apiculture in Great Britain. The 

 prevalence of this complaint and the present high cost 

 of bee appliances and of stocks render it extremely 

 doubtful whether any profit can be derived from the 

 keeping of bees solely for honey production. Many 

 bee-keepers find it more profitable to supply bees and 

 queens, together with the necessary apparatus, and 

 hundreds who take up bee-keeping relinquish it after 

 a short time as being non-productive. 



The disease has continued without interruption 

 from about the year 1902 until the present time, and I 

 no epidemic of an equally permanent and extensive ' 

 nature has so far been indisputably recognised outside j 

 the British Isles.. The first preliminary investigation j 



t 



* "Isle of Wight Disrase in Hive Bees." (t) "The Ftiology of the ' 



Disease." Rv D^ J. Ronnie, P. R. White, and Elsie T. Ha'veyCpp 739-54'). j 



'2) I' The Pathology of Isle of Wight Disease in Hive Bees " By P. B , 

 White (pp. 756-64). (S) " I«le of Wieht Diserise in Hive Bees — Experiments 

 on Infection with Tarsonrjiius H'ooiii, n.sp." Bv Elsie J. Harvey 



(op. 765-67). (4) " Is'e of Wight Di-:ea«e in Hiv» Bees— Acarine Disease: | 



The Oreanism Associated with the Disease — Tarsoiietnus Wopili, n.sp." ^ 



Bv Dr. J. Rennie(pp. 768-70, pi. i, fig 2). Trans. Royal Soc. Edinburgh, ] 

 vol. Hi., part iv., No. 29, 7921. 



into its cause v^-as carried out in the Isle of Wight in 

 1907 by the present writer, who described many of 

 its symptoms, but was unable to discover anv 

 protozoa connected with it. In 1912 and 1913 Graharn 

 Smith and others put forward the theory that it was 

 due to Nosema apis. More recent work by Anderson 

 and Rennie and by Rennie and Harvey indicates that 

 Isle of Wight disease and disease due to Nosema are 

 two distinct complaints exhibiting different symptoms 

 and pathological conditions. 



In the first of the papers under review the 

 causal organism of Isle of Wight disease is 

 definitely stated to be a new species of mite, 

 Tarsonemtis Woodi. This Acarine was found in 

 every one of no stocks reported by trustworthy 

 bee-keepers, or certified by the investigators them- 

 selves, as suffering from Isle of Wight disease. The 

 investigation involved an examination individually of 

 at least 700 bees, and it was discovered that in every 

 instance where symptoms of Isle of Wight disease 

 were evident the mite was also present. No 

 exception has been found. The parasite occupies 



NO. 2687, VOL. 107] 



