John Wesley Powell

“ During growth, which is an increase of form and structure by a succession of changes, it also exhibits a new mode of motion, which is vitality or life, and the cessation of this activity is death, when the plant returns to the geonomic world by decay. But assimilation, growth and life are continued from one generation to another, and imply time from period to period. ”

“ The love of truth born of the generations of thinking minds forever engaged with the materials of consciousness in the process of inference, ultimately establishes a habit and love of truth that submits every judgment to the tribunal of congruity, the court of equity which every man erects in his own soul. ”

“ The plant is thus subject to inexorable conditions by its inheritance, and these conditions restrict its growth to the course pursued by its ancestors; but heredity is not the only factor of causation involved; the environmental factors may succeed in preventing, arresting or modifying the development of the plant. When the plant arrives at maturity and produces other germs, they also are subject to the laws of heredity; but the inheritance which they receive has accumulated in the development of the parent. Thus as generations pass there is secular development. ”

“ When it starts the frost may nip it, the sunlight may fail it because of an overhanging shade, herbivorous animals may devour it, man may dig it up. All of a multitude of conditions are necessary that a plant may mature; and these causes may be traced to the ultimate supply of food, as effecting the assimilation, to external forms which cast destructive shadows or protect from destruction, or they may be traced to external forces, so that there are heredity conditions and environmental conditions. ”

“ If we treat of the assimilation of plants, the phytology of plants, the vitality of plants or the heredity of plants through germs, we seem to take the whole subject in view, for the concomitants are not disparate but only abstract in consideration. ”

“ The entire plant is engaged in these operations as long as life lasts, sleeping in partial rest by night and hibernating in semi-torpidity during the winter, but carrying on its operations in full vigor when the sun is genial. Assimilation deals with particles so minute that even the eye of the microscope cannot see them, and they can be known only when aggregated in masses as material for use or as products, but the operations are carried on particle by particle in such a manner that what is and what becomes reveal the method of becoming only to the eye of reason ”

“ It has often been surmised, and sometimes taught, to be choice. It seems to be the same thing in plant life, but there are other phenomena which appear in plants which suggest that the ultimate particles have not only the power of choosing their atomic and molecular associates, but they also seem to have the power to a limited degree to choose the attitude of their phytons toward external objects in space. Thus certain phytons seek the soil where they may perform the function of roots, and others seek the air where they may perform various functions in the plant life. ”

“ We are yet to follow properties through higher degrees of relativity. For this purpose it becomes necessary to examine the relations exhibited by plants in metabolism, growth, vitality, and heredity. Plants are not wholly disparate bodies, but rise by a discrete step or degree in relativity not exhibited in ethronomy, astronomy and geonomy. ”

“ Now a new element of time appears, for by producing germs and thus multiplying individuals like itself the same stages of metabolism, growth and life observed in the parents are repeated in the offspring. This new element is heredity, in which the offspring inherits the potentiality of the parent as it is restricted within certain narrow limits to careers of metabolism, growth and vitality similar to that of the parent. ”

“ Thus generations are generations of processes. The processes are assimilation, construction and destruction, growth of form and structure, vitality exhibited in endosmosis and exosmosis, and finally processes are repeated by heredity represented by parents and children. ”

“ A system of phytons constitutes the higher plants. In the history of plant life the morphology of plant phytons is an important part of the science of botany, for the forms of phytons undergo a succession of changes, the investigation of which vies in importance with that of the chemical development of kinds to which we have heretofore alluded. ”

“ Experience in the laboratory may pile up facts, prophecy in the laboratory may be fulfilled in multitudinous cases; but under the decrees of the court of congruity if any incongruity appears the chemist is turned again to his experiments, resting assured that somewhere his facts or theories are wrong, and he plunges into his labors to reach peace only when congruity is found. ”

“ We find in plants the same essentials: unity, extension, speed, and persistence as they are compounded into the properties of number, space, motion, and time, and as they are further developed as time, form, force, and causation ”

“ III The plant is a laboratory for the evolution of many substances; but as the particles of which they are composed have number and as they are arranged in numerical, that is, molecular orders, they have at the same time extension, and their arrangement implies that they are placed in forms. Thus having considered generations of kinds, we are led to the consideration of generations of forms, and the forms which we have to consider are forms of cells, forms of tissues, forms of phytons and forms of plants. Plants also exhibit forms of crystals ”

“ Doubtless gravity exerts a direct influence upon the functions of the plant, but this influence has had inadequate examination. Stress and strain are exhibited as endosmosis and exosmosis, exhibited to us in the circulation of fluids through the membranes of the cells, and is an important theme in the physiology of plants. ”

“ Heat and its modification as light and perhaps as electricity and magnetism play an important role in vitality, which has been subject to much investigation by the observation of nature and artificial experimentation. The vitality of the plant is accelerated by heat, and becomes torpid when it is insufficient. ”

“ Some plants are single cells, other plants are aggregates of loosely attached cells joined together as threads or as webs of threads as in the slimes, but in plants of a little higher grade these webs are consolidated by a woof of plant tissue as in some of the lichens and seaweeds. ”

“ When the different classes of plants are examined in this respect, the succession appears in the development of classes, those plants of the lower classes passing through morphologic stages which are repeated in higher classes and continued to still higher stages, so that the plants of the highest class practically include all of the stages in succession as exhibited in the order of the lower classes. ”

“ The normal and developed cell has three concentric envelopes which may be called blasts, the whole enclosing a nucleus, so that the structure which we found in the earth as spheres is repeated here as blasts. ”