Jan. lo, 1884] 



NA TURE 



249 



the segments of a sphere. If you take a flexible cylinder and 

 cover it v\ ith a more or less inflexible skin or sheath, and bend 

 that cylinder sidewi-e, you of course will find that the fractures 

 <'f that part of the surface «ill take place alon^ the line of 

 the shortest curve, which is on the side ; and, as a matter of 

 fact, you have breaks of very much the character of the segment-; 

 of the Permian batrachia. It may njt be so symmetrical as in 

 the actual animal, for organic growth is symmetrical so far as 

 not interfered with ; for, when we have two force*;, the one of 

 gi-owth and the other of change or alteration, and they contend, 

 you will find m the organic being a quite symmetrical result. 

 That is the universal rule. In the cylinder bending in this way, 

 of course the .-.horte.st line of curve is right at the centre of the 

 side of that cylinder, and the longest curve is of course at the 

 summit and ba^e, and the shortest curve will be the point of 

 fracture. And that is exactly what I presume has happened in 

 the case of the construction of the segments of the sheath of the 

 vertebral column in the Literal motion of the animl swimming 

 always on one side, and which at least has been the .tctuil c u;e 

 of the disposition of the osseous material in its form. I have 

 gone beyond the state of the discussion in calling attention to 

 one of the forces which have probably produced tliis kind of 

 result. That is the st ite of the vertebral column of many of 

 the vertebrata of the Permian period. 



I go back to the mammalia, and call attention to the teeth. 

 The ordinary tooth of the higher type of the mamma'ia, whether 

 hoofed or no', with some exception-:, is complex with crets or 

 cusps. In cutting the complex grinding surfaces we find they 

 have been derived by the unfolding ex ensions of four original 

 cu-ps or tubercle-'. They have besn flattened, have been 

 rendered obli(|ue, have run together, have folded up, have be- 

 come spiked, have descended dee(Iy or have lifted them- elves, 

 so that we have teeth of all sorts and kinds, oftentimes very 

 elegant, and sometimes very effective in mechanism. In many 

 primary ungulate--, the primitive condition of fuur cmical 

 tubercles is found. In pa- sing to older periods we find the 

 mammalia of the Puerco period, m hich never have more than 

 three tubercles, wi;h the exception of three or four specie's. In 

 the succeeding periods, however, they get the fourth tubercle on 

 the posterior side. Finally, you get a complicated sei-ies of 

 grinding or cutting apparatus, as the case may be. 



Last, but not least, we take the series of the brain. No 

 doubt the generalisation is true, that the primitive forms of 

 ma.umalia had small brains with smioth hemispheres; later 

 ones had larger brains with tomplet hemispheres. In general, 

 the carnivora have retained a more simple form of brain, while 

 herbivorous animals have retained a most complicated type of 

 brain. The lowest forms of mammalia display the additional 

 peculiarity of having the middle brain exposed, and the hemi- 

 spheres or large lobes of the brain, which are supp sed to be 

 the seat of the mental phenomena, are so reduced in size at the 

 back end that y> u see the middle brain distinctly, thou^^h it is 

 smaller than in reptiles and fishes. It is beyond the possibility 

 of controversy that these series have exi-ted, and that they have 

 originated in simplicity, and have resulted in complication ; and 

 the further deduction must be drawn, that the process of succes- 

 sion has always been toward- greater effectiventss of mechanical 

 vork. There are cases of degradation, as in the growing defi- 

 ciency in dentition in man. There is no doubt that a large 

 number of people are now losing their wisdjm-teeth in both 

 jaws. 



We are now brought to the question of the relations which 

 mind bears to these piinciples. The question as to the nature of 

 mind is not so complex as it might seem. There is a great deal 

 of it, to be sure ; but on examination it resolves itself into a few 

 ultimate forms. An analysis reduces it to a few principal types 

 or departments — the departments of intelligence and of emotions 

 (with their m-^dified smaller forms, likes and dislikes), and the 

 will, if such there be. Those three groups, proposed by Kant, 

 are well known, and adopted by many metaphysicians ; and they 

 stand the scrutiny of modern science perfectly well in both men 

 and the lower animals. But the question of the material of the 

 mind, the original raw stuff out of wh-eh mind was made, is one 

 which is claiming attention now from biologist, as it always has 

 done from physiologists proper and physicians. This is sensi- 

 bility, mere simple sensibility, unmodified sensibility, or co..- 

 sciou-ness. Sensibility, in connection with memory, is sufficient 

 for the accomplishment of wonderful results. It is only neces- 

 sary to impress the sensibility wiih the stimuli which this world 

 affords, whether from the outside or the inside, to have the 



record made, and to have the record kept. Among wonderful 

 things this is perhap; the most wonderful : that any given form 

 of matter should be able to retain a record of events, a record 

 which is made during a state of sensibility for the most part, a 

 greater or less degree of sensibility, which is retained in a 

 state of insensibility, a:id is finally returned to the sensibility by 

 some curious process of adhesion, and the results of impresses 

 which are found on the material tissue concerned. 



And these simple elements of mind are found in animals. No 

 zoologist who has perception or honesty, nor any farmer or 

 breeder, nor any person who has charge of animals in any way, 

 can deny sensibiliiy to all the lower animals at times. The 

 great stumbling-block ir. the way of the thinker in all this 

 field is the great evane. cence of this sensibility: the great ease 

 with which we di sipate it, the readiness with which we can 

 deprive a fellow-being of his sense, is a stumbling-block in 

 more ways than one. While it is a question of the greatest 

 difficulty, nevertheles-;, like other departments of nature, doubt- 

 less it will ultimatelv be explained by the researches of physio- 

 logist-'. I only need to call attention to the fact as an important 

 factor in evolution. 



Of course, if these structures are suggested, affecting the 

 mechanical apparatus, the question arises whether they were 

 ma e ready to hand, whether the animal, as soon as he got it, 

 undertook to use it, and whether he undertook to use the 

 organism under the dire stimuli of necessity, or amended through 

 ages these modifications in his own structure. We ate told by 

 some of our friends that law implies a Lawgiver, that evolution 

 implies an Evolver ; the only question is. Where is the Law giver ? 

 where is the Evolver? where are they located? I may say, it is 

 distinctly proven in some directions, that the constant applica- 

 tions of force or motion in the form of strain-', in the form of 

 impacts and blows, upan any given part of the anim.al organism, 

 do not fail to produce results in change of structure. I believe 

 the changes in the ungulates to which I have called your atten- 

 tion are the result of strains and impact^, precisely as 1 have 

 shown }ou the manner of the fracture of the vertebral column of 

 the primitive vertebrates of the Permian period. This would 

 require long di-cussion to render clear ; nevertheless I verdure to 

 make the assertion that this series of structiu-es is the result 

 of definite and distinct organic forces, directed to special 

 ends. We have yet to get at the conflicting forces which 

 have produced the results w e see. Mechanical evolution will 

 give us a good deal to do for some time to come. Of 

 course, if motion has had an effect in modifying structure, 

 it behoves us to investigate those forces which give origin to 

 motion in animals. Fir.-t in onier came the sensii ilities of the 

 animal, which we have traced to simple consciousness ; stimuli, 

 upon notice of which he immediately begins to move. The 

 primary stimulus of all kinds of motion is necessarily touch. If ' 

 a stone falls upon the tail of some animal which has a tail, he 

 immediately gets out of that vicinity. If a jellyfish with a 

 stinging ap])ar..tu- runs across an eel which has no scales, the 

 eel promp'ly removes. External applications of unpleasant 

 bodies will always cause an animal to change his location. Then 

 he is constantly as-aulttd by the dire ei.emy of beasts, hunge", 

 which is an instinct which is evidently universal, to judge froai 

 the actions of anima's. This seems to have fa hioued, in large 

 1 art, all forms of life, from the least to the greatest, from the 

 most unorganised to the most complex. Each exercised itself 

 for the purpose of filling its stomach with protoplasm. Then 

 come the stimuli, which should be included under the class of 

 touch, changes of temperature. No animals like to be cold or 

 too hot ; and when the temperature is disngreeable the tendency 

 is to go a« ay from that locality. Among primary instincts must 

 be included that of reproduction. After that comes the sen.sa- 

 tion of reistance, or, carried to a high degree, of anger: when 

 an animal's interests are interfered with, its movements resisted, 

 it prompts to the most energeiic displays. So you see it is a 

 matter of necessity that mental phenomena lie at the back of 

 evolution, alvvays provided that the conned ing link of the argu- 

 ment— that motion has ever affected stiucture — be true. That 

 is a point which of course admits of much discussion. I have 

 placed myself on the affirmative side of that question ; and, if 

 I live long enough, I expect to see it absolutely demonstrated. 



Of couse the development of mind becomes possible under 

 such circumstances. It is not like a man lifting himself up by 

 his boots, which it would be if he had no such thing as memory. 

 But with that memory which accumulate-', which formulaies first 

 habits, and then structure-, especially in the sjft, delicate 



