August 1 6, 1877] 



NA TURE 



311 



vascular development in the ventral aspect of the body ; while 

 the heart of the invertebrate, whether in the more concentrated 

 form existing in the articulata and muscula, or in a more 

 subdivided shape prevalent in the annelida, is most frequently 

 dorsal ; yet the main aoita of the vertebrates is also dorsal ; 

 and it is not impossible through the intermediate form of 

 amphioxus, to understand how the relation between the verte- 

 brate and the invertebrate type of the blood-vascular system 

 may be maintained. 



But I am warned by the lapse of time that I must not attempt 

 to pursue these illustrations further. In the statement which 

 I have made of some of the more remarkable phenomena of 

 organic production— too long, I fear, for your endurance, but 

 much too brief to do justice to the subject — it has been my 

 object mainly to show that they are all more or less closely related 

 together by a chain of similarity of a very marked and unmistak- 

 able character ; that in their simplest forms they are indeed, 

 in so far as our powers of observation enable us to know them, 

 identical ; that in the lower grades of animal and vegetable 

 life they are so similar as to pass by insensible gradations into 

 each other ; and that in the higher forms, while they diverge 

 most widely in some of their aspects in the bodies belonging to 

 the two great kingdoms of organic nature, and in the larger 

 groups distinguishable within each of them, yet it is stdl possible, 

 from the fundamental similarity of the phenomena, to trace in 

 the transitional forms of all their varieties one great general pl.rn 

 of organisation. 



In its simplest and earliest form that plan comprises a 

 minute mass of the common nitrogenous hydrocarbon compound 

 to which the name of protoplasm has been given, exhibiting 

 the vital properties of assimilation, reproduction, and irritability ; 

 the second stage in this plan is the nucleated and inclosed 

 conaition of the protoplasmic mass in the organised cell. We 

 next recognise the differentiation of two productive elements, 

 and their combination for the formation of a more highly-endowed 

 organising element in the embryonic germ-sphere or cell ; and 

 the fourth stage of advance in the complexity of the organising 

 phenomena is in the multiplication of the fertilised embryo-cell, 

 and its conversion into continuous organised strata, by further 

 histological chan^^es in which the morphological foundations of 

 the future embi-yo or new being are laid. 



I need not now recur to the further series of complications in 

 the formative process by which the bilaminar blastoderm is 

 developed, and becomes trilaminar or quadrilaminar, but only 

 recall to your recollection that while these several states of tlie 

 primordial condition of the incipient animal pass insensibly 

 into each other, there is a pervading similarity in the nature of 

 the histological changes by which they are reached, and that in 

 the production of the endless variations of form assumed by the 

 organs .and systems of different animals in the course of their 

 development, the process of cell-production, multiplication .ind 

 differentiation remains identical. The more obvious morpholo- 

 gical changes are of so similar a character throughout the whole, 

 and so nearly allied in the dilTerent larger groups, that we are led 

 to regard them as placed in some very close and intimate relation 

 to the inherent properties of the organic substance which is their 

 seat, and the ever-present influence of the vital conditions in which 

 alone these properties manifest themselves. 



The formative or organising property, therefore, resides in the 

 living substance of every organised cell and in each of its com- 

 ponent molecules, and is a necessary part of the physical and 

 chemical constitution of the organising elements in the conditions 

 of life ; and it scarcely needs to be said that these conditions 

 may be as varied as the countless numbers of the molecules 

 which compose the smallest particles of their substance. Hut, 

 setting aside all speculation of a merely pangenetic kind, it 

 appears to me that no one could have engaged in the study 

 of embryological development for any time without becoming 

 convinced that the phenomena which have been ascertained as to 

 the first origin and formation of textures and organs in any indi- 

 vidual animal are of so uniform a character as to indicate forcibly 

 a law of connection and continuity between them ; nor will his 

 study of the phenomena of development in dilTerent animals have 

 gone far before he is equally strongly convinced of the similarity 

 of plan in the development of the large: groups, and, to some 

 extent, of the whole. I consider it impossible, therefore, for any 

 one to be a faithful student of embryology, in the present state of 

 science, without at the same time becoming an evolutionist. 

 There may still be many difficulties, some inconsistencies, and 

 much to learn, and there may remain beyond much which we shall 



never know ; but I cannot conceive any doctrine professing to 

 bring the phenomena of embryonic development within a general 

 law which is not, like the theory of Darwin, consistent with their 

 fundamental identity, their endless variability, their subjugation 

 to varying external influences and conditions, and with the 

 possibility of the transmission of the vital conditions and pro- 

 perties, with all their variations, from individual to individual, 

 and, in the long lapse of ages, from race to race. 



I regard it, therefore, as no exaggerated representation of the 

 present state of our knowledge to say that the ontogenetic 

 development of the individual in the higher animals repeats 

 in its more general character, and in many of its specific 

 phenomena, the phylogenetic development of the race. If we 

 admit the progressive nature of the changes of development, 

 their similarity in different groups, and their common characters 

 in all animals, nay, even in some respects in both plants and 

 animals, we can scarcely refuse to recognise the possibility of 

 continuous derivation in the history of their origin ; and how- 

 ever far we may be, by reason of the imperfection of our know- 

 ledge of palceontology, comparative anatomy, and embryology, 

 from realising the precise nature of the chain of connection by 

 which the actual descent has taken place, still there can be little 

 doubt remaining in the minds of any unprejudiced student of 

 embryology that it is only by the employment of such an hypo- 

 thesis as that of evolution that farther investigation in these 

 several departments will be promoted so as to bring us to a 

 fuller comprehension of the most general law which regulates the 

 adaptation of structure to function in the universe. 



SECTION A. 



mathematical and physical. 



Opening Address by the President, Prof. G. Carey 

 Foster, F.R.S. 



When any one fears that he has accepted a duty that is too 

 difficult for him, or that he has allowed himself to be placed in 

 a position, the responsibilities of which are greater than he can 

 properly discharge, probably the very worst thing he can do is 

 to proclaim his misgivings to the world. But though I fully 

 believe in this rather obvious maxim, I cannot avoid sayin? that 

 I enter upon my duties here to-day with very great diffidence, 

 and that I feel the necessity of asking your indulgence at the 

 outset for what I fear will be my inevitable shortcomings in dis- 

 charging the functions of the honourable post that has been 

 assigned to me. And I am sure that no one who calls to mind 

 the names of some of those who, within recent years, have occu- 

 pied the Chair of this .Section, and who knows — however im- 

 perfectly — what those names stand for in connection with 

 mathematics and physics, will be surprised that I should 

 deprecate comparisons which might tend to degenerate into 

 contrasts, or that I should shrink from having my performances 

 measured by the standard of such predecessors. But I have 

 neither the right nor the desire to detain you longer with this 

 purely personal topic, and I therefore proceed to ask your atten- 

 tion to matters more closely connected with the business which 

 has brought us here. 



The periodically recurring character of these meetings im- 

 avoidably suggests, at each recurrence, a retrospect at the 

 scientific work of the year, and an attempt to estimate the 

 advances which have been the result of this work. At first 

 sight nothing would seem to be more natural or appropriate 

 than that each president of a section should occupy the intro- 

 ductory remarks, which the custom of the Association demands 

 from him, with an account of the chief forward steps made 

 during the past year in the branches of science represented by 

 his Section. 



Very little consideration, however, is sufficient to show that, 

 in the case at least of Section A, to give anything like a general 

 report of progress would be a task which few, if any, men could 

 perform single-handed. To say nothing of the enormous amouitt 

 of the material which is now the result of a year's scientific 

 activity, the varUly — or I might even say the unlikeness — of the 

 subjects of which this Section takes cognizance is so great that, 

 in most cases, it would be safe to conclude, from the mere fact 

 of a man being able, adequately to expound the recent advances 

 in one of these subjects, that he must have given so much atten- 

 tion to this one as to have made it impossible for him to have 

 followed carefully the progress of the rest. 



But even supposing that all presidents of Section A were able 



