Febeuaey 4, 1898.] 



SCIENCE. 



149 



inating successively each of the factors 

 which can affect any vital process, can 

 alone give answer. We may not live to 

 see it, but perhaps it ia not impossible that, 

 though not a spontaneous generation of or- 

 ganisms, a planned generation of living 

 m.atter may be effected under the eyeof the 

 experimenter. 



Of the grosser directly biologic problems 

 facing the botanist, none is more simple in 

 appearance, nor apparently more difficult 

 of solution, than that attending the rise of 

 crude sap from the root to the leaf of one of 

 the higher plants. Purely physical in the 

 wonderful osmotic action of the absorbent 

 cells, and purely physical in the evapora- 

 tive action of the foliage, the flow of sap 

 has a middle part to which the laws of phys- 

 ics elsewhere have not been fitted ; and yet 

 this conduction in the main is carried on 

 through tissues which are dead. Here, too, 

 the isolation, one by one, of all disturbing 

 possibilities offers the onlj' control of ex- 

 periments from which final conclusions are 

 to be drawn. 



The plant has not a nerve system. It is 

 true that its protoplasm communicates 

 from cell to cell through all of the living 

 parts, but no differentiated chain of cor- 

 puscles exists for the transmission of sen- 

 sation, or whatever else you choose to call 

 it, from organ to organ, much less from 

 operative organs to a central control organ ; 

 and yet there are plants which are called 

 irritable or sensitive; organs which, if 

 touched, coil about a support — clasp, for 

 digestive purposes, prey ; leaves which, for 

 protective purposes, drop into an incon- 

 spicuous position, or into a position expos- 

 ing them less to the heat of the mid-day 

 sun or I'adiation into the cold of night. 

 These movements are said to be reactions 

 to stimuli, manifestations of protoplasmic 

 irritability ; but those who have looked 

 deepest into them find the difiiculties of 

 explaining the exact process multiplied the 



further they go. Division of the problem, 

 division of labor, experimentation and ob- 

 servation under conditions most favorable 

 for the normal growth of the plant, are the 

 means of reaching a solution. 



We owe it chiefly to Darwin that a 

 science of ecology has sprang into life. 

 The German school would call it biology, 

 but it is not precisely what is immediately 

 considered here as biologj'. It is the inter- 

 relations between living things and between 

 them and their surroundings. All that, 

 with loose expression of teleological pur- 

 pose, would be called ' adaptation' belongs 

 here. Many facts are well known. The 

 theories advanced for their explanation 

 often seem to explain them, but the theories 

 concerning their origin are not always so 

 satisfactory. Who can say that with more 

 knowledge we may not discard even the 

 most fundamental of them ? Observation 

 and difierential experimentation are here 

 means to the end, no less than elsewhere. 

 How do plants react to their surroundings 

 in nature — -under cultivation ? How have 

 their species come into existence in their 

 present form ? The general fact that they 

 do react, and that they have been evolved 

 from preexistent types by a process in some 

 degree of the survival of the fittest, is cur- 

 rently believed. The horticulturist to-day 

 produces what he openly calls species in 

 the vegetable kingdom. Are not his meth- 

 ods indicative of the line to pursue in an- 

 swering the more recondite questions of de- 

 scent and multiplication ? 



In conclusion, to come to that in which 

 more nearly I myself am compelled to work, 

 I wish to state that the study of local 

 floras — the study of the flora of one's back 

 yard in a city, of his stone wall, of the roof 

 of his house, if we have an old house, of 

 an old cheese-box — is far from being a 

 mere determination and enumeration of 

 the several species represented. It is be- 

 coming a census of the individuals, an 



