Q4 Elliot, Inheritance of Acijuircd Character!- [);>mi:iry 



Now what is horcdity. how did it originate, and how can 

 it cause individual variability? An explanation cannot he found 

 in the higher organisms, hut must he sought tor, according to 

 Weismann, in unicellular organisms, or those in which no dis- 

 tinction exists between body and germ-cells ; and which repro- 

 duced bv tission, or division, when the two descendants of an 

 individual are nothing more than the two halves of that individ- 

 ual. It is undisputed and acknowledged* by Weismann, that 

 imicellular organisms are acted upon by external influences, and 

 that these cause variations of size, color, form and number or ar- 

 rangement of cilia, and these resulting characters are transmitted 

 to the otFspring, and he remarks "We are thus driven to the con- 

 clusion that the ultimate origin i>f hereditary individual ditlerences 

 lies in the direct action of external influences upon the organ- 

 ism," and that when individual ditlerence had been attained In- 

 unicellular organism, '"it necessarily passed over into the higher 

 organisms when they fust appeared." Does it not seem reason- 

 able then to suppose that when these latter organisms received 

 these inherited characters, they also obtained the power of trans- 

 mitting direct adaptations derived from their environment? Re- 

 garding the evolution from cells of one kind (Protozoa) to cells 

 of two or more kintls (Metazoa) cooperating in the same or- 

 ganism. Prof. Lloyd Morganf argues that '•Whenever and how- 

 ever this occurred the new phase of developmental reproduction 

 must have had its origin. And if in cell-division there is any 

 continuitv of protoplasmic power, the faculty of producing 

 diverse cooperating cells would be transmitted. On any view of 

 the origin of the metazoa, this diverse or developmental repro- 

 duction is a new protoplasmic taculty ; on any view it must have 

 been transmitted, for otherwise the metazoa would have ceased 

 to exist." But Weismann claims that in multicellular or higher 

 organisms these variations could not originate and be transmitted, 

 and illustrates this by citing* the improbability of a pianist, who 

 by practice had developed the -'muscles of his fingers so as to en- 

 sure the highest dexterity and power," being able to transmit this 

 power to his oflspring, because, according to his view, the eflect 

 would be entirely transient, as it would be unable to produce any 



*Essays. 2d ed. pp. 285, 286. 

 tAnim. Life and Iiitell. p. 143. 



