April 28, 192 1] 



NATURE 



267 



What is biology ? Who are biologists ? So far as 1 

 am able to judge, biology is commonly regarded as a 

 side-show of natural history ; and any zoologist and 

 botanist is supposed to be, ex officio, a biologist. But 

 biology is an interpretative science, and systematic 

 zoology and botany are purely descriptive. 1 hey may 

 furnish valuable evidence, but they do not necessarily 

 do so. The zoologist or botanist trained in observa- 

 tion and description may interpret skilfully, but such 

 skill is not a necessary outcome of his studies. Zoo- 

 logists and botanists have themselves proclaimed the 

 inadequacy of their evidence by founding the experi- 

 mental and biometric schools, which began as violently 

 opposed sects, and so continue. 



To my thinking, biology is that science which sits 

 at the hub of all the studies concerned with life — 

 zoology, botany, physiology, psychology, medicine, 

 bacteriology, embryology, anatomy, palaeontology, 

 sociology, even pedagogy and history — gathers evi- 

 dence from them all, and deals esjjecially with 

 problems too big or deep for these individual studies, 

 e.g. problems of heredity, evolution, development, and 

 the like. If the biologist be controlled by the rules 

 which ordinarily guide scientific procedure — for 

 example, the rule that all verifiable and relevant facts 

 (no matter how, or by whom, or when, or where 

 collected) are equal before science, by the rule that 

 all hypotheses must be crucially tested [i.e. so tested 

 by fresh and unlike facts that every alternative hypo- 

 thesis is rendered inconceivably as true), and by the 

 rule that a fully established theory must be accepted 

 as true regardless of all preconceptions — then a very 

 splendid future immediately awaits not only biology, 

 but also science in general; for the claim of science 

 to the deciding voice in the settlement of numerous 

 burning problems of immense importance will become 

 irresistible. 



By way of demonstrating that I am not vapouring, 

 I shall venture to give one or two examples of evi- 

 dence ignored and problems neglected by biology "as 

 she is spoke " in a future communication. Mean- 

 while, there is a little more in Mr. Cunningham's 

 letter with which it is necessary to deal. He says 

 that naturalists would not admit that man, as an 

 animal, is "higher" than an insect. It is pleasant to 

 find him so careful of meanings; but will he please 

 excuse theexpression as " technical " ? It is in common 

 use and deceives no one. He declares that I give 

 no evidence of the evolution of the power of develop- 

 ing in response to use. Is there any need? A man 

 develops from birth to death mainly in response to 

 this influence; does Mr. Cunningham believe that a 

 butterfly develops in the same way to an equal extent? 

 Consider mind. All learning, thought, intelligence, 

 and reason depend on the growth of the mind through 

 functional activity. Mr. Cunningham has done 

 magnificent work on hormones. Does he think a 

 beetle could learn what he has taught? What is 

 intelligence but a power of developing in response to 

 experience, of growing mentally in response to func- 

 tional activity? What is stupidity but a "natural" 

 or "acquired" incapacity so to profit? A- human 

 infant can learn, but has not learned. A human idiot 

 cannot learn, and has not learned. A normal man 

 can learn, and has learned. Almost all that separates 

 the normal adult mentally from the infant and^ the 

 idiot develops in response to use. The perfect idiot 

 cannot even learn to walk or to speak. From the 

 human point of view every dog is an imbecile, every 

 cat an idiot, every beetle a perfect idiot. The beetle is 

 more efficient than the human idiot rnerely because he 

 is more completelv equipped with instincts^ and instinc- 

 tive actions, which, unlike human habits, habitual 

 actions, and the rest, do not develop through use. 



NO. 2687, VOL. 107] 



For example, the beetle does not learn to use his 

 limbs. Does not the difference between man and the 

 beetle indicate an evolution of the power of developing 

 in response to use? What more evidence does Mr. 

 Cunningham want? G. Archdall Reid. 



9 Victoria Road South, Southsea, April 23. 



The "Flight" of Flying-fish. 



In Nature of April 21 Prof. Wood-Jones presents 

 some interesting observations on the "flight" of 

 flying-fish made from an especially favourable vantage- 

 point — the overhanging bow-sheaves of a cable ship. 



While crossing the Gulf of Mexico on various occa- 

 sions 1 made some observations on the same subject 

 with the aid of powerful binoculars (Gperz prismatic, 

 magnifying 12 diameters). With these I had been 

 used to following birds in flight, and with a little 

 practice found that I could keep flying-fish under con- 

 tinuous observation during their passage through the 

 air. 



I can confirm Prof. Wood-Jones's account in the 

 following important particulars : — 



(i) The initial impulse is always given by rapid 

 lateral strokes of the tail as the fish leaves the water. 

 Since the lower lobe of the caudal fin is elongated, 

 the fish can continue to propel itself in this manner 

 for some time while the whole of its body is out of 

 the water. On very calm days the moving lower lobe 

 of the tail leaves a track in the water in the form 

 of an interrupted line. Presumabh the interruptions 

 represent the times of violent lateral motion. The 

 uninterrupted sections of line are each 2-3 in. long, 

 the interruptions rather longer, the whole line often 

 continuing for 5-6 ft. After this, of course, the fish 

 rises wholly into the air. 



(2) The fish may regain impetus by again vibrating 

 its tail when it has dropped far enough for the lower 

 tail-lobe to be once more in the w-ater. Fresh impetus 

 may be gained in this way once, twice, or even three 

 times in a flight without the body ever touching the 

 water. 



(3) The pectoral fins are usually held stiffly out, as 

 Prof. Wood-Jones states, and act as planes. I have, 

 however, on several occasions seen rapid vibration of 

 the pectoral fins for a short period ; but whether this 

 was actual "flight," as I at the time supposed, or 

 whether it was due, as Prof. Wood-Jones suggests, 

 to a passive vibration caused by the air meeting the 

 fin at a certain angle, I am unable to say. The 

 impression made upon me at the time was that the 

 normal means of propulsion in air was the tail, but 

 that the. pectoral fins could be used as supplementary 



', flying organs on occasion. Of the truth of the first 

 part of this impression I have no doubt whatever ; 

 Prof. Wood-Jones's anatomical studies make me 

 doubt the second part. However, a good binocular 

 in the hands of anyone trained to field observation 

 will put the matter to the test. 



Julian S. Huxley- 

 New College, Oxford. April 25. 



The Concept of " Space " in Physics. 



Prof. Eddixgton (Nature, April 14, p. 201) ex- 

 presses well the properties that a substratum of matter, 

 light, and electric force should have, and the reasons 

 for combining space and aether, the two different, but 

 always co-existing, substrata of the older physics, 

 into one. What is not clear is why he stops there. 

 The ancient rule. " Entities are not to be multiplied 

 beyond necessity," is as applicable now as ever. If 

 a physical aether is to be postulated, it is for those 

 who advocate it to show their reason for doing so. 



