Vitaliiy and Organization of Proloplasm. 33 



irritation be sufiiciently intense the entire substance of the amoeba will 

 contract into a globule. During the formation of a pseudopodium an 

 expanding surface is offered to the stimulating influences of the medium, 

 and the ensuing disintegration, accompanied by contraction, is very 

 ol viously an effect of these stimulating influences. The proximate 

 cause of contraction is thus observably chemical disintegration induced 

 byi external stimulation. Xormal stimulation functionally disintegrates 

 the expanding living substance, and, in consequence of it, -it contracts. 



But something additional occurs during the contraction of proto- 

 l^lasm; something most essential to what constitutes its vitality, and 

 which imparts to vital motility one of its most characteristic features. 

 Each functionally disintegrated portion or particle of protoplasm serves 

 as restitutive material to other disintegrated portions or particles. A 

 chemically^ equilibrating vital commotion is thereby set going, which 

 spreads more or less vividly throughout the entire protoplasmic in- 

 dividual. It is this process of reintegration by means of complemental 

 chemical blending of adjacent portions of protoplasm that causes the 

 remelting of the stagnated protoplasm of pseudopodia. And spreading 

 from' part to adjoining part it gradually involves the entire substance 

 of the functionally disintegrated pseudopodium, whereby it acquires the 

 tendency to contract into globular form. Shrinking thus within itself, 

 it ends by being reincorporated into the substance of the protoplasmic 

 body, with which it chemically blends. 



This essential vital process of complemental restitution, by means of 

 the chemical blending of portions^ of functionally disintegrated proto- 

 plasm, can most conspicuously be observed when two or more stagnated 

 pseudopodia meet, and thereupon visibly coalesce, contracting into glob- 

 ular form. But in each separate pseudopodium stagnation on exposure 

 to external stimulation is followed by a lively play of complemental 

 restitution, by means of the chemical blending of adjacent portions of 

 protoplasm to more and more complete reintegration, involving the en- 

 tire substance of the pseudopodium as a formative whole, and causing 

 the molecular commotion and the mass-movement in which the contractu 

 phase of vital motility consists. 



But something still more profoundly vital is implicated in that which 

 causes a pseudopodium to be reincorporated into the body of the proto- 

 plasmic individual. Fragments of protoplasmic individuals have, as is 

 well known, the tendency to reintegrate or regenerate the whole organ- 

 ism from which they are derived. A disintegrated pseudopodium is 

 really a fragment of the protoplasmic individual from which it has 

 issued, and its reincorporation is partly due to its own tendency, as well 

 as to that of the rest of the protoplasmic being, to become fully reinte- 

 grated, and to form thus a unitary whole. We shall find in the course 

 of our interpretation of vital phenomena that reintegration of the in- 

 dividual, as a whole, from fragments of the same, is playing the most 

 essential part in ontogenetic evolution. 



The living substance has generally been looked upon as pre-eminently 



