148 



SCIENCE. 



[N. S. Vol. VII. No. 162. 



which are exposed, or upon which much 

 devolves, are here bound together by a 

 wonderfully developed class of nerve cells, 

 along which, from the center of sensation, 

 travels an impulse which, through terminal 

 dendrites, may establish and re-establish 

 itself in that wonderful phenomenon which 

 we call memory, and though the metabolic 

 processes connected with the maintenance 

 of animal temperature and with nerve struc- 

 ture and nerve action are more complex 

 and less diiferentiable than in the vegetable 

 kingdom, so that the plant is frequently 

 turned to for an illustration of simple cell 

 action ; the green cell performs that added 

 function of photosynthetically recombining 

 the elements of simple unassimilable com- 

 pounds into assimilable organic compounds, 

 which by specialized structures are con- 

 verted into organized substance, which 

 again, by the action of secreted enzymes, 

 is digested and fitted for transportation to 

 points where it may be wanted for use, 

 while these same compounds are still 

 further synthetized by the incorporation of 

 nitrogen, for the most part in relatively 

 simple organic combination, so that it is by 

 no means certain that the simplest field for 

 the study of protoplasmic activity is af- 

 forded by the plant. Here, then, in the 

 nutritive changes induced by and occurring 

 in this delicately balanced vehicle of vital 

 manifestations, lies the seat of one great 

 problem : Is life life, or is it an attribute of 

 matter ? Does the synthesis of organic mat- 

 ter stop with the formation of the vegetable 

 carbohydrate or the vegetable reserve pro- 

 teid, or does the one pass into the other, 

 which in its turn grades into the living 

 protoplasm of the cell, the molecules of 

 which, during active life, undergo contin- 

 uous mutations and shifting combinations 

 from the nutrient to the living and from 

 the living to the excreted form ? A part of 

 this question has been answered. What 

 shall be the answer to the other part? and 



if physical, what is to be said as to a positive 

 suspension of protoplasmic activity, amount- 

 ing to functional death, and of a revivifica- 

 tion of protoplasm which actually has been 

 dead? 



One must concede that in plants, as in 

 animals, death inevitably comes, sooner or 

 later — unless one chooses to juggle with 

 terms in an eifort to prove that the unicel- 

 lular organism, the individual cambium cell 

 and the like are immortal. But in what 

 does it consist ? 



In medicine a system of pathology has 

 been worked out by which the theory and 

 practice of a generation ago have become 

 the science and art of to-day. For plants 

 a science of pathology just as complicated, 

 just as useful for the preservation of the life 

 of the individual, remains to be worked out. 

 Does disease cause ' loss of vitality,' or 

 is this merely an expression of imperfect 

 nutrition or clogging by waste products ? 

 What is ansesthesia? Is it a temporary 

 reduction of vitality in certain cells, or an 

 enveloping of their molecules by the inhib- 

 iting agent or its derivatives ? 



What is reproduction ? What is hered- 

 ity? The vehicle of each, as of every 

 other vital phenomenon, is protoplasm ; 

 more, it is known that nuclein is directly 

 concerned in the reproductive processes, 

 and the technique of to-day has enabled it 

 to be shown, for plants as for animals, that 

 certain parts of certain cells unite. The 

 physical or visible basis for a theorj'^ of the 

 transmission of characters is more nearly 

 reached to-day than ever before, but is the 

 real essence of the problem any nearer 

 elucidation? Why does the fertilized 

 gamete of the alga produce a seaweed, 

 and of the phanerogam a flowering plant? 

 Why does the meristem of the oak produce 

 oak leaves on all branches ? 



An analysis and subanalysis, to the last 

 degree, of all of those phenomena which we 

 call vital, and a chain of experiments elim- 



