September 23, 1897] 



NATURE 



49: 



the effect that too much attention can easily be paid to 

 water-power, is well worth bearing in mind. That such 

 power costs little or nothing is obviously far from being 

 a fact, when one takes into account the cost of the plant 

 and the rent of the waterfall, a rent that will tend to in- 

 crease more and more as the owners of the ground realise 

 its value. On the other hand, while water-power is 

 sought high and low for electrical purposes, the waste 

 gases from blast furnaces and coke ovens represent 

 surplus energy, which passes away unused in many 

 modern works, to the extent of hundreds, or even thou- 

 sands, of horse-power units. There is here open, thinks 

 Dr. Borchers, a field which can and will be at once 

 successfully used by electro-metallurgy. 



OUR BOOK SHELF. 



The Mammoth Cave of Kentucky. An Illustrated 

 Manual. By Horace C. Hovey, A.M., D.D., and 

 R. Ellsworth Call, A.M., Ph.D. Pp. v + i lo. (Louis- 

 ville : John P. Morton and Co., 1897.) 

 Nearly a century has passed since the wonderful 

 Mammoth Cave of Kentucky was found by a hunter 

 who entered it in pursuit of a wounded bear. The cave 

 is one of many which occur in the limestone regions of 

 Kentucky and other States of the Central West. It is 

 stated by Dr. Hovey that there are as many as four 

 thousand sink-holes — one covering an area of not less than 

 two thousand acres— and five hundred known caverns, 

 in Edmonson County alone. The Mammoth Cave is 

 not the most interesting from a scientific point of view, 

 nor is it so beautifully decorated with stalactites as the 

 adjacent White Cave, but it transcends the others in the 

 grandeur of its dimensions. So far as is at present 

 known, there is only one entrance to the cave ; from it 

 two principal lines of e.xploration have been laid out, 

 and they are both described in detail in the manual 

 before us. 



It is really refreshing to read a guide-book of the kind 

 which Drs. Hovey and Call have given us. Instead of 

 extravagant descriptions of the scenic features, and of 

 imaginary resemblances found in stalactites and stalag- 

 mites, we have a fair amount of interesting information 

 on the causes which produce such formations, and on 

 the natural history of the cavern generally. In a section 

 on the geological features of the cave we read (p. 96) : 



" The rocks which contain Mammoth Cave, and all 

 the caverns surrounding it, are of Sub-carboniferous age. 

 There are but two members of the Sub-carboniferous 

 included in the vertical section, and they are the Chester 

 Sandstone, which forms the immediate surface rock, of 

 varying thickness, and the St. Louis Limestone, largely, 

 in this section, oolitic, in which the great body of the 

 cave is formed. Between these members, but not always 

 present, is a variant layer of conglomerate, from which 

 are derived most of the siliceous pebbles which are 

 found in the floor of the cavern in certain places." 



The fauna and flora of the cave are briefly described, 

 and a list is given of the various forms of life which are 

 certainly known to live in the cavern at the present 

 time, the places where they are generally found being 

 also described. Dr. Call has himself collected and 

 studied the animals of the cavern, and has added a 

 number of interesting forms to the list of those previously 

 known. It is pointed out that, with the exception of the 

 blind-fish {Amblyopsis spelceus), which was described by 

 Dr. De Kay in 1842, the earliest descriptions of animals 

 from the Mammoth Cave were by Europeans. Two blind 

 beetles, one blind spider, and a blind crayfish were first 

 ■described by Dr. Tellkampf in 1844. 



.\< . 1456, VOL. 56] 



A nij^p of the cave is appended to the volume, and a 

 number of pleasing plates illustrate various parts and 

 formations. The authors are familiar with every part of 

 the cave, and their scientific training enables them to 

 see and understand more of the nature of things than 

 an untrained observer. We could not desire a better 

 guide-book to the subterranean wonderland of Kentucky 

 than the one they have produced. 



The Survival of the Unlike : a Collection of Evolution 

 Essays suggested by the Study of Domestic Plants. 

 By L. H.' Bailey. Pp. 515. (London: Macmillan 

 and Co., Ltd., 1896.) 

 The book before us consists of a number of addresses 

 delivered during a period extending over several years. 

 They are of unequal merit, b'.it nevertheless are all well 

 worth reading, and some of them are remarkable both for 

 their vigour and the stimulating interest of their contents. 

 To the evolutionist there is much food for reflection. 

 As Dr. Bailey truly says, the evolution of species is 

 going on all around us, and nowhere can the process 

 be more readily followed than in the case of cultivated 

 plants. He emphasises the extraordinary amount of 

 diversity to be seen within the limits of a species, 

 and indeed even in the different branches of the same 

 tree, and he shows pretty conclusively that in the case of 

 apples, for example, different types which are character- 

 istic for certain regions, may be traced back with 

 certainty to a single parent form. This is of special 

 j interest as proving that new races may arise by a process 

 I of selection within the limits of vegetative (not seminal) 

 propagation. In fact the author himself goes so far as 

 ' to say that "there is no essential difference between 

 bud-varieties and seed-varieties, apart from the mere 

 ; fact of their unlike derivation ; and the causes of 

 ! variation in the one case are the same as those in the 

 other.'' Further, "that much of the evolution of the 

 i vegetable kingdom is accomplished by wholly sexless 

 ^ means." There is no doubt, however, that although we 

 may sometimes he&ilate to follow him in his conclusions. 

 Prof Bailey's arguments merit attention, and will have 

 ; to be reckoned with. He has a terse and epigrammatic 

 I way of driving home his meaning which is refreshing, 

 ! and he really strikes a note of needed warning in saying, 

 i " I sometimes think that we are substituting for the 

 I philosophy of observation a philosophy of definitions." 



Extremely interesting are the pages devoted to the 

 ! evolution of some of our vegetables, flowers, and fruits, 

 ' and, amongst the latter, mention may be specially made 

 I of the tomato and the strawberry. 



{ Altogether the book may be commended to a wide 



' circle of readers. It is clear in style as well as forcible 



in diction, and its author has made good use of a wide 



range of facts from sources which are-not, to every one, 



readily accessible. 



The Eye as an Aid in General Diagnosis : a Handbook 

 for the Use of Students and General Practitioners. 

 By E. H. Linnell, M.D. Pp. 248. (Philadelphia : 

 The- Edwards and Docker Company, 1897.) 

 The general fact that a person's state of health may be 

 judged from the expression of the eye is well known. In 

 the book before us Dr. Linnell shows that every tissue of 

 the eye at times affords points of diagnostic importance. 

 .A.S he points out, " Examination of the eyes affords 

 valuable aid not only in the diagnosis of diseases of the 

 central nervous system, but also of constitutional affec- 

 tions and diseases of other organs." It is to obtain a 

 wider recognition of the relations of diseases of the eye 

 to general diseases, and to place before the student and 

 family physician the experience of a specialist as to the 

 eye symptoms which are valuable in diagnosis, that this 

 book has been written. The volume will doubtless prove 

 a serviceable handbook of diagnosis to the general prac- 

 titioner. 



