Vitality and Organization of Protoplasm. 47 



enlightenment. Not until Grubcr's researches on "the artificial division 

 of Infusoria/' 1884-5, and M. Mnssbaum's investigations of "sponta- 

 neous and artificial division," 1884, and on "the divisibility of the 

 living substance," 188G, was there a new fruitful impetus given to the 

 attempt at scientifically explaining this astonishing process of organic 

 reintegration. Wonderful and most instructive results have since been 

 experimentally attained in this field of research by a number'of investi- 

 gators; an account of which, with much original matter has been lately 

 given in Morgan's excellent work on "Regeneration." It is becoming 

 more and more certain that this power of fragments, detached from 

 organic beings, to regenerate the entire adult form from which they . 

 are derived ; that this regenerative_pjOwer is one of the most fundamental y> 

 proj>orties of the living substance. 



As to the relative smallness of fragments capable of regenerating the 

 entire organism, Lillie found that fragments of the substance of Stentnr, 

 measuring only 1-27 of the volume of the adult infusorium, retain still 

 the power to regenerate the entire individual. And still more decisive 

 in this respect was the great discovery that single blastomeres, and '^ven 

 mere small fragments of egg-plasm possess the power to reproduce the 

 complete embryo. As early as 1870 Haeckel observed that pieces of the 

 segmented egg of Medusae were capable of regenerating complete ani- 

 mals. 0. and E. Hertwig, Bovery, Driesch, ]VIorgan and others found that Ly 

 single blastomeres, or pieces of egg-plasm of sea-urchins reproduce the 

 entire embryo. Wilson showed that similar results can be obtained with 

 Amphioxus; Herlitzka with salamanders; Zoja with jellyfish; Morgan 

 with fish, etc. 



It is certain, then, that even small fragments of the substance com- 

 posing protoplasmic individuals of highly complex structure, and even 

 fragments of their egg or germ-plasm, have power to reintegrate, regen- 

 erate, or reproduce the entire structure and form of the organism from 

 which they are derived. This process of gradual reintegration is evi- 

 dently genuine organic growtji^ Consequently, organic growth does no- 

 wnse consist in the new formation and aggregation of multitudes of sep- 

 arate vital units, but quite essentially in the power of fragments of the 

 living substance to reintegrate, regenerate, or reproduce the entire proto- 

 plasmic individual from which they are derived.* 



On the strength of numerous instructively varied experiments on 

 artifically induced regeneration, and considering that even small frag- 

 ments of egg-plasm are capable of reproducing the entire embryo, it is, 

 I think, not far-fetched to conclude that_normal reproduction is like- 



*"Da nun das Ziel des normalen Wachsthums zanz dasselbe ist, niimlicli die 

 Herstellimf? eines vollstandigen Individuiims. so ist im Wesentlichen Wachsthum 

 die Erreichuns einer bestinimten chemischen Vollendung der lebendi<?en Substanz, 

 vermittelst Wiedervervollstandiffiuifr eines fiinktionell abgetrennten Fragments 

 derselben." Jenaische Zoitscbrift fiir Natunviszenschaft, XVIII. p. 699, 1882. 

 In tbis neglected article all essential observations and explanations concerning 

 vitality and organization bere again brought forward will be found clearly and 

 explicitlj' recorded. 



