February 9, 1905] 



NA TURE 



341 



subject, the nervous control of .pupillary movements. 

 A review of the work done on the question of the 

 course of the pupillo-dilator fibres is given. These 

 fibres pass from the cervical sympathetic as a separate 

 tract along the carotid towards the Gasserian 

 ganglion, and run thence with the ophthalmic division 

 of the trigeminal along the nasal branch to the long 

 ciliary nerves, thus avoiding the ciliary ganglion. The 

 final portion of the lecture is devoted to a discussion 

 of the cortical localisation of pupillary movements. 

 We agree with Mr. Parsons that a very critical spirit 

 is necessary in dealing with this subject. Here, more 

 than anywhere else, is to be found the " elusive 

 factor " which, upsets all hypotheses. The term 

 " synkinesis " seems to have a sufficiently useful 

 application in neurological nomenclature to justify its 

 invention. The limits of this notice do not allow of 

 more detailed criticism. We must, however, con- 

 gratulate Mr. Parsons on the singularly lucid, though 

 necessarily inconclusive, fashion in which he has dealt 

 with subjects of great complexity and importance. 



The Tuieniieth Century Atlas of Microscopical Petro- 

 graphy. Part ii. With four plates. (London : 

 Thos. Murby, 1904.) 



Since the note on this work appeared in Nature (vol. 

 Ixxi. p. 38), we have been informed that the " editor " 

 of it is Mr. E. Howard Adye, who is, in fact, re- 

 sponsible both for the text and for the very delicate 

 plates. The second part includes two igneous rocks 

 from Edinburgh, the Carboniferous oolite of Clifton, 

 and the beautiful green quartzite of Ightham, de- 

 scribed by Prof. Bonney in 1888. This last rock, we 

 believe, usually contains altered glauconite in addition 

 to the minerals mentioned by the author. We fancy 

 that Mr. Adye is familiar with biological writing, 

 which makes his descriptions rather more severely 

 technical than is customary among English geologists. 

 We thus read of a " dark brown fenestrated region at 

 the periphery," " hypo-odontoid outgrowths," " bio- 

 genetic formation," and so forth. We do not know, 

 moreover, what degree of extraordinary accuracy is 

 suggested by the phrases " completely polarised light " 

 and " fully-crossed Nicols." The text, however, is 

 usually clear and graphic. The four rock-sections 

 accompanying the part, and issued through the labor- 

 atory of Mr. J. R. Gregory, are absolutely perfect 

 specimens of an art rarely cultivated in the British 

 Isles. G. A. J. C. 



Ahbildiiiigen der in Deutschland und den angrenz- 

 enden Gebieten vorkommenden Grundformen der 

 Orchideen-arten. 60 Tafeln nach der Natur gemalt 

 und in Farbendruck ausgefuhrt von Walter Miiller 

 (Gera) mit beschreiben dem Text von Dr. F. 

 Kranzlin (Berlin). Pp. xiv + 60 + plates. (Berlin : 

 R. Friedlander und Sohn, 1904.) Price 10 marks. 



This is a series of sixty coloured plates representing 

 the orchids which occur in Central Europe. The 

 introduction and the text are from the pen of Dr. 

 Kranzlin, who tells us at the outset that the book is 

 not intended for professed botanists, but for those who 

 take an interest in botany, or who possess a love of 

 flowers. ■ For this reason it is, we suppose, that the 

 minutise of anatomical structure and the details of 

 physiology are but lightly touched on. The reader, 

 however, has put before him in a very clear way the 

 principal points in the morphology of this most in- 

 teresting group, together with an account of the 

 conformation of each species. 



A general statement is made as to the geographical 

 distribution of the several plants, but no precise indi- 

 cations of particular localities are given. Most of 



NO. I 84 1, VOL. 71] 



our European orchids are terrestrial and have tuberous 

 roots, but Liparis Loeselii, a species very rare in 

 Britain, has a distinct pseudo-bulb such as charac- 

 terises most of the tropical epiphytes of this order, and 

 a similar form of stem occurs in Microstylis niono- 

 phyllos, so that the formation of a pseudo-bulb is not 

 correlated solely with the epiphytic habit. Both the 

 tuber and the pseudo-bulb serve as food stores for the 

 growing plant. In Goodyera repens there is a creep- 

 ing underground stem which also recalls that of its 

 tropical congeners. These points and others of a 

 similar character are well represented in the plates. 

 These illustrations were executed from life by Mr. 

 Walter Miiller, and they are so truthful that we may 

 commend them to the notice of orchid lovers. Our 

 field botanists will find all the British species repre- 

 sented, as well as a few others that are not members 

 of the British Flora. 



Intensification and Reduction. By Henry W. Ben- 

 nett. Pp. xv+124. (London : IlifTe and Sons, Ltd., 

 1904.) 

 This issue. No. 15 of the Photography Bookshelf 

 Series, will form a useful addition to an already 

 valuable set of handbooks. The author has wisely 

 restricted himself to setting forth in a clear and con- 

 cise manner the better methods employed in intensifi- 

 cation and reduction, and has not burdened the 

 beginner with an elaborate index to all possible 

 methods past and present. The processes dealt with 

 are treated in some detail, so for this reason the 

 reader should gain a good working knowledge of 

 the manipulations he has in hand. The distinctive 

 qualities of each method are clearly brought out, 

 making the selection of any one for a particular 

 negative quite an easy matter. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for tliis or any other part of Nature. 

 No notice is taken of anonymous communications.^ 



Slow Transformation Products of Radium. 



In a recent number of the Philosophical Magazine 

 (November, 1904), I have shown that radium, after passing 

 through four rapid changes, finally gives rise to two slow 

 transformation products, which, on the scheme of changes 

 there outlined, were called radium D and radium E. 



These two products can be separated from each other by 

 suitable physical and chemical methods. Radium D, which 

 is the parent of E, gives out only B rays, while E gives out 

 only a rays. It was calculated that D should be half trans- 

 formed in forty years, and E in about one year. Evidence 

 was also shown that radium D was the active constituent in 

 the radio-active lead of Hofmann, and that radium E was 

 the active substance present in both the polonium of Mme. 

 Curie and the radio-tellurium of IMarckwald. 



Later work has confirmed these conclusions. I have 

 examined the rates of decay of the activity of radium E and 

 of radio-tellurium, a.nd have found them to be identical. 

 Each loses half its activity in about 150 days, instead of 

 the calculated period of one year. The specimen of radio- 

 tellurium was obtained from Sthamer, of Hamburg, in the 

 form of a thin film deposited on a polished bismuth rod. 

 I find that the same value for the decay and activity of 

 radio-tellurium has recently been obtained by Meyer and 

 Schweidler {Akad. d. Wiss. Wien., December i, 1904). 



I was, unfortunately, unable at the same time to 

 determine accurately the decay of the activity of polonium. 

 .V specimen of polonium (ratio-active bismuth) had been in 

 mv possession for three years, and had during that time lost a 



