October 15, 1891] 



NATURE 



5^3 



elusions as to evolution and heredity. The fundamental idea of 

 this weighty work is the conception of the Idioplasm, namely, 

 of a definite portion of the general protoplasm, to which alone is 

 committed the transiuission of hereditary characters. This idea, 

 as Weismann points out, is a fruitful one, and will live, and is 

 indeed incorporated in all recent theories of heredity. Nageli's 

 speculations, however, as to the details of the distribution 

 and molecular stiuclure of this idioplasm are of much more 

 doubtful value, and rest on no firm basis of actual observation. 



Niigeli rightly argues that the character of the fertilized egg 

 must be determined by a minute amount of idioplasm and 

 not by the cytoplasm generally, because the characters of the 

 male and female parent are on the average equally represented in 

 the offspring in spite of the enormous difference in the bulk of 

 the cytoplasm of spermatozoid and ovum. 



It was only, however, after the idioplasm had been identified 

 by Weismann and Strasburger with a definite constituent of the 

 nucleus that the theory acquired a positive basis. 



Niigeli in the " Abstammungslehre " points out that fertili- 

 zation can only consist in the direct union of solid idioplasmic 

 bodies, and thus on theoretical grounds arrives at a conclusion 

 which has been fully confirmed by the observations of Van Bene- 

 den, Strasburger, and Guignard. He also shows that while in the 

 higher organisms idioplasm alone is necessarily transmitted from 

 parents to offspring, in the increase of the lower plants and 

 animals by division, the descendants acquire a share of the nutri- 

 tive protoplasm also. Hence in the latter the conditions of 

 culture may directly affect the descendants, as Nageli found in 

 his observations on bacteria. These views are in essential 

 agreement with those of Prof. Weismann on the continuity of 

 the germ-plasm, as brought forward a year later, though 

 on other points there is a wide divergence of opinion. 



Nageli insists in his preface to this book, that the subject 

 of heredity can only be authoritatively treated by a physiologist, 

 and he no doubt regarded his micellar theories as an im- 

 portant contribution to the question. In this his view is some- 

 what one-sided, and as a matter of fact all recent advance 

 in our knowledge of the essential points in reproduction has 

 come from the morphological side. 



Nageli's attitude towards the question of spontaneous genera- 

 tion is interesting. In his early days he had no doubts as to the 

 spontaneous origin of many Fungi, and thought that this could 

 be experimentally demonstrated. In 1865 he gave up the ex- 

 perimental evidence, but believed in the origin de novo at all 

 epochs of simple vegetable cells. In the " Abstammungslehre " 

 he still maintains that spontaneous generation is constantly in 

 progress, but no longer holds that even the lowest known 

 organisms can arise in this way. His supposed primitive living 

 things [Probien) are as much more simple than bacteria, as these 

 are more simple than the highest animals or plants. 



As regards he causes of evolution, Nageli in his great work 

 appears to limit the field of natural selection even more 

 narrowly than in his earlier essays. Its function, according to his 

 later views, consists in the separation and definition of races by 

 the elimination of ill-adapted forms, rather than in determining 

 the origin of the races themselves. In a brilliant illustration he 

 pictures natural selection as pruning the phylogenetic tree, though 

 powerless to cause the putting forth of new branches. He still 

 regards evolution as a necessary progress towards perfection 

 determined by the constitution of the organism itself, and more 

 especially of its idioplasm. 



This view is only needed if we assume with Nageli the exist- 

 ence of purely morphological characters — of characters, that is, 

 which are not, and never have been, of the nature of adapta- 

 tions. It appears to us to have been sufficiently shown by Prof. 

 Weismann and others that the existence of such characters is an 

 unnecessary assumption. As biology advances, we learn every 

 • lay the function of characters which had before appeared to us to 

 be useless, and the whole tendency of investigation is to prove 

 that all characters whatsoever are either of direct use to their 

 present possessors or have been inherited from ancestors, to 

 whom, at the time when they were acquired, they were equally 

 advantageous. It would be difficult to cite a stronger instance 

 of a " morphological character " than the alternation of genera- 

 tions which so clearly characterizes the higher cryptogams. Yet 

 it has been lately shown by Prof. Bower that this may well have 

 been an adaptive character at its first origin, the sporophyte 

 being adapted for taking possession of the dry land, while the 

 oophyte, owing to the mode of fertilization, was compelled to 

 retain a lowly and semi-aquatic habit. 



NO. II 4 6, VOL. 44] 



We have given a very incomplete and imperfect sketch of the 

 life-work of one of the most illustrious of that illustrious band 

 of botanists to whom the chief advances of our science are due. 

 Much of his work has of necessity been left quite unnoticed. 

 But on even a cursory glance through the writings of Nageli the 

 conviction is forced upon us that he was a man not only of 

 exceptionally wide scientific and philosophical training and of 

 great literary power, but also one of real genius, and as far 

 removed as possible from that narrow specialism which is the 

 besetting sin of so much modern scientific effort. The judg- 

 ment of Nageli's colleague, Prof. Cramer, that he was "a truly 

 great man," cannot be dismissed as the exaggerated language of 

 personal affection, but expresses a truth. Though some of his 

 theories may be abandoned, a vast sum of permanent achieve- 

 ment will always remain, and the influence of Nageli on the 

 future of our science will be powerful and lasting. 



D. H. Scott. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Oxford. — Full term commences on Saturday, October 17. 

 The following lectures in science generally have been adver- 

 tised : — 



The Savilian Professor of Geometry (J. J. Sylvester) will 

 lecture on surfaces of the second order, illustrated by the models 

 with which that department has been supplied at the request of 

 the Professor. 



The Professor of Astronomy (Rev. C. Pritchard) proposes to 

 lecture on the methods of determining astronomical constants, 

 and offers practical instruction with the transit circle and solar 

 spectroscope. 



Rev. Bartholomew Price (Sedleian Professor of Natural 

 Philosophy) lectures on hydromechanics. 



The Professor of Experimental Philosophy (R, B. Clifton) 

 will lecture on electricity ; and instruction in practical physics is 

 offered by Mr. Walker and Mr. Hatton at the Clarendon 

 Laboratory. Lectures on mechanics and experimental physics 

 are offered by Rev. F. J. Smith, at the Millard Laboratory. 



The Waynflete Professor of Physiology (J. S. Burdon-Sander- 

 son) will lecture on the subjects required for the final examina- 

 tion in the School of Physiology, and Mr. Dixey will lecture on 

 histology. Practical instruction on this latter subject will be 

 given by Mr. Kent. 



In the subject of Chemistry, the Waynflete Professor (W, 

 Odling) will lecture on animal products, while the Aldrichian 

 Demonstrator (W. W. Fisher) will give a series of lectures on 

 the non-metallic elements. Mr. J. Watts lectures on organic 

 chemistry, and the instructiori in practical work is under the 

 supervision of Mr. Watts, Mr. Veley, and Mr. J. E. Marsh. 



The Deputy Linacre Professor of Human and Comparative 

 Anatomy (E. Ray Lankester) offers a course of lectures on com- 

 parative anatomy and embryology. This course is intended for 

 seniors. There will also be a junior course for beginners and 

 candidates for the preliminary examination in animal morphology 

 conducted by the Deputy Linacre Professor and Dr. W. B. 

 Benham. This last-named gentleman will also lecture on the 

 Chsetopoda. 



The Professor of Geology (A. H. Green) offers two courses 

 of lectures, one on physical, the other on stratigraphical 

 geology. 



The Reader in Anthropology (E. B. Tylor) will lecture on 

 the origin and development of language and writing. 



The Sherardian Professor of Botany (S. H. Vines) lectures, 

 this term, on elementary botany. 



The Hope Professor of Zoology (J. O. Westwood) lectures 

 and gives informal information upon some of the orders of 

 Arthropoda. 



In the department of medicine, Sir H. W. Acland, Bart., 

 gives informal instiuction on modes of medical study. This 

 instruction is given at the Museum, where arrangements will be 

 made for one or more demonstrations in illustration of subjects 

 bearing on public health. Dr. Collier and Mr. Morgan give 

 demonstrations for the Professor on Medical and Surgical 

 Pathology. The Lichfield Lecturer in Clinical Medicine (W. 

 Tyrrell Brooks) will lecture on the physical signs of disease, 

 and the Lecturer in Clinical Surgery (A. Winkfield) offers 

 instruction on the treatment of fractures, &c. 



The Lecturer in Human Anatomy (A. Thomson) offers a 



