August 23, 1895.] 



SCIENCE. 



215 



two sparrows or two honey bees as nearly 

 alike as possible were selected, the nervous 

 system of one being fixed in the morning 

 after the night's rest and that of the other 

 after a day of toil, the changes in the cells 

 of the brain of the honey bee or sparrow 

 and in the spinal ganglia of the sparrow 

 were as marked as in case of artificial fa- 

 tigue. After prolonged rest then the nerve 

 cells are charged, so to speak — they are full 

 and ready for labor, but after a hard day's 

 work they are discharged, shrunken and ex- 

 hausted. 



There is one more step in this brilliant 

 investigation. If in the morning after sleep 

 and rest animals and men are full of vigor, 

 and in the evening are weary and ex- 

 hausted, how like is it to the beginning and 

 end of life ? In youth so overfiowing with 

 vigor that to move, to act, is a pleasure 

 and continued rest a pain. But in the 

 evening of life a warm corner and repose 

 are what we try to furnish those whose 

 work is done. How is this correlated in 

 the cells of the nervous system with the 

 states of rest and fatigue? With a well- 

 nourished child which died from one of the 

 accidents of birth the nerve cells showed 

 all the characters of cells at rest and fully 

 charged. In a man dying naturally of old 

 age the cells showed the shrunken nuclei 

 and all the appearances of exhausting fa- 

 tigue. In the one was the potentiality of a 

 life of vigorous action ; the other showed 

 the final fatigue — the store of life-energy 

 had been dissipated and there was no re- 

 covery possible. 



For the animals that possess an un- 

 doubted nervous system probably all would 

 admit that there is some sort of nervous 

 action corresponding to sensation ; but 

 what of living matter in the humbler forms 

 where no nervous system can be found ? 

 That these have vital motion, that they 

 breathe, nourish themselves, grow and pro- 

 duce oifspring, none can deny. Do they 



have anything comparable with sensation ? 

 As most of the lower forms are minute, the 

 microscope conies to our aid again, and in 

 watching these lowliest living beings it is 

 found that they discriminate and choose 

 going freely into some portions of their 

 liquid world and withdrawing from other 

 portions. If some drug which is unusual, 

 or we must believe disagreeable, is added to 

 a part of the water they withdraw from 

 that part. It seems to have the same 

 effect as disagreeable odors on men and 

 animals. On the other hand, there are sub- 

 stances which attract, and into the water 

 containing these they enter with eagerness. 

 Strange is it too that as proved by experi- 

 ment if an unattractive substance is used, 

 and also one on the other side that has 

 been still more attractive, the less disagree- 

 able is selected, the less of two evils is 

 chosen. 



As man, the horse, dog and many other 

 animals adapt themselves gradually to tem- 

 peratures either very cold or very warm, and 

 that too by a change in their heat- regulating 

 power rather than by a change of hairy or 

 other clothing, so these lowly organisms 

 are found in nature in water at tempera- 

 tures from near freezing up to 60°-80° C, 

 a point approaching that of boiling water. 

 It may be answered that each was created 

 for its place ; but by means of a microscope 

 and a delicate thermostat, to be certain of 

 every step and to see all the results. Dr. 

 Dallinger through a period of seven years 

 accustomed the same unicellular organism 

 and its progeny to variations of tempera- 

 ture from 15°-20° C, i. e., about the tem- 

 perature of a comfortable sitting-room, up 

 to 70° C. For those at the cooler tempera- 

 ture it was death to increase rapidly the 

 temperature 10°, and for those at the higher 

 temperature it was equally fatal to lower 

 the heat to 15°-20°, their original normal 

 temperature. These examples seem to show 

 that it is one of the fundamental character- 



