11 



SCIENTIFIC SIDE-LIGHTS 



Adaptation 



standing low in the scale of organization, 

 possess some degree of intelligence. This 

 will strike every one as very improbable; 

 but it may be doubted whether we know 

 enough about the nervous system of the 

 lower animals to justify our natural dis- 

 trust of such a conclusion. With respect to 

 the small size of the cerebral ganglia, we 

 should remember what a mass of inherited 

 knowledge, with some power of adapting 

 means to an end, is crowded into the minute 

 brain of a worker-ant. DARWIN Formation 

 of Vegetable Mold, ch. 2, p. 28. (Hum., 

 1887.) 



52. ADAPTATION OF ORGANS TO 

 MIND The Secret of Man's Supremacy. 

 And when we remember that the immense 

 variety of organic forms in the existing 

 world does not exhaust the adaptability of 

 their plan, but that the still vaster varieties 

 of all the extinct creations have circled 

 round the same central types, it becomes 

 evident that these types have had from the 

 first a purpose which has been well and 

 wonderfully fulfilled. As a matter of fact, 

 we see that the original conception of the 

 framework of organic life has included in 

 itself provisions for applying the principle 

 of adaptation in infinite degrees. Its last 

 development is in man. . . . There are 

 stronger arms, there are swifter limbs, there 

 are more powerful teeth, there are finer 

 ears, there are sharper .eyes. There are 

 creatures which go where he cannot go, and 

 can live where he would die. But all his 

 members are coordinated with one power 

 the power of thought. Through this he has 

 the dominion over all other created things 

 whilst yet as regards the type and pattern 

 of his frame he has not a single bone or 

 joint or organ which he does not share with 

 some one or other of the beasts that perish. 

 It is not in any of the parts of his struc- 

 ture, but in their combination and adjust- 

 ment, that he stands alone. ARGYLL Reign 

 of Law, eh. 4, p. 120. (Burt.) 



53. ADAPTATION OF PARALYTIC TO 

 NEW CONDITION Increase of Muscular 

 Force for Same Movement Effect of Prac- 

 tise. A patient who is partly paralyzed in 

 leg or arm, so that he can only move the 

 limb with very great effort, has a distinct 

 sensation of this effort: the limb seems 

 heavier than it used to be, as tho weighted 

 with lead; that is to say, there is a sensa- 

 tion of greater expenditure of force than be- 

 fore, altho the work actually done is the 

 same or even less. For the performance of 

 this amount of work there is required an 

 innervation of abnormal intensity. In the 

 same way, the patient will deceive himself, 

 especially in the first stages of the disease, 

 with regard to the extent of his movements. 

 His steps are short and uncertain; his 

 hand misses the objects which he is reach- 

 ing for. By degrees, if his condition re- 

 mains unchanged for a long time, he regains 

 more or less precision of movement; prac- 



tise gives him familiarity with his new sys- 

 tem of muscle-sensations. WUNDT Psychol- 

 ogy, lect. 9, p. 136. (Son. & Co., 1896.) 



54. ADAPTATION OF PLANT TO ANI- 

 MAL FOOD Secretion Poured Out When Ob- 

 ject To Be Digested. It is a much more re- 

 markable fact that when an object, such as 

 a bit of meat or an insect, is placed on the 

 disk of a leaf, as soon as the surrounding 

 tentacles become considerably inflected, 

 their glands pour forth an increased amount 

 of secretion. I ascertained this_by selecting 

 leaves with equal-sized drops on the two 

 sides, and by placing bits of meat on one side 

 of the disk ; and as soon as the tentacles on 

 this side became much inflected, but before 

 the glands touched the meat, the drops of 

 secretion became larger. This was repeated- 

 ly observed, but a record was kept of only 

 thirteen cases, in nine of which increased 

 secretion was plainly observed; the four 

 failures being due either to the leaves being 

 rather torpid, or to the bits of meat being 

 too small to cause much inflection. We must 

 therefore conclude that the central glands, 

 when strongly excited, transmit some influ- 

 ence to the glands of the circumferential ten- 

 tacles, causing them to secrete more copious- 

 ly. DARWIN Insectivorous Plants, ch. 1, p. 

 11. (A., 1900.) 



55. ADAPTATION, PRIMITIVE, OF 

 HANDLES TO TOOLS In almost every 

 section of North America occurs the 

 " grooved ax," and there grow a great many 

 varieties of wood, like ash or hickory, whose 

 saplings will bend double without breaking 

 and will easily split. The Indians were ac- 

 customed to take a piece of one of these 

 saplings about six feet long and split it, so 

 that, in bending about the groove of the ax 

 or adz or hammer, it would neatly fit. The 

 halting was completed by securely seizing 

 the sides together near the working piece 

 and at the grip. . . . This style might 

 have been seen in the United States any- 

 where between the two oceans. MASON 

 Origins of Invention, ch. 2, p. 37. (S.," 

 1899.) 



56. ADAPTATION TO ENVIRONMENT 

 BY ANIMALS Deep-sea Organisms with 

 Movable Plates Adjustable to Pressure. 

 In shallow-water sea-urchins the shells are 

 composed of a great number of little plates 

 that fit so closely to one another that no 

 movement is possible between them. When 

 the animal dies all the soft tissues decay 

 and the shell remains, to be tossed about by 

 the waves until crunched or dashed to 

 pieces. In Phormosoma, however, the tiny 

 plates of which the shell is composed are 

 freely movable on one another, and when the 

 animal is alive very considerable contrac- 

 tions and expansions can take place. None 

 of the modern shallow- water echinoids pre- 

 sent this peculiarity, and it is a very inter- 

 esting and surprising fact that in this re- 

 spect the fossils of the chalk should re- 



