posits that each and every part of an organism produces "gemmules" during every stage of the organism's development from embryo to adult.
The word gene was derived from Hugo De Vries's term pangen, itself a derivative of the word pangenesis
which Darwin (1809-1882) had coined in 1868.
His theory of pangenesis
, for example, states that each part of the adult body produces gemmules that make their way into the sexual organs for reproduction; in this way, traits acquired by adults can be passed on to their young.
This is not a direct inheritance of acquired characteristics through a means such as Darwin's pangenesis
, but an indirect transmission through operant behavior, social learning, genetic assimilation, and natural selection.
En su obra elemens de physiologie, escribe: "En este sistema (pangenesis
), placenta y envolturas [resultan] imposibles de explicar." Este tipo de critica, desde luego, fue el que Haller y Bonnet plantearon convincentemente en contra de Buffon.
He was wrong, however, about genetics, concocting his neo-Lamarkian theory of pangenesis
at the same time as Mendel was conducting his experiments.
In my February 2012 article, "Darwin's Invention: Inheritance & the 'Mad Dream' of Pangenesis
" (American Biology Teacher 74, 86-91), I inadvertently combined one of the Darwin quotes with commentary of mine.
La distincion importante entre la transmision y el desarrollo quedara mejor grabada en el entendimiento si recurrimos a la hipotesis de la pangenesis
; segun esta, cada unidad o celda del cuerpo despide ciertas yemecillas o atomos no desarrollados que, transmitidos a los descendientes de ambos sexos, se multiplican por division en varias partes.
The pendulum subsequently oscillated once more toward pangenesis
, gaining tentative adherence among others from Charles Darwin, according to whose "Provisional Hypothesis of Pangenesis
" the complete body contributes to heredity: atoms from the entire body of both mother and father are united in their offspring.
I began this story in the previous issue of ABT, in which I recounted the fascinating story of Charles Darwin and his invention of a mechanism of inheritance called "pangenesis
" (McComas, 2012).
Two different theories had currency in his time: Hippocractic "pangenesis
," the notion that sperma comes from all parts of the body and thereby provides the parts of the body for the offspring; and the "preformationist" or "homunculus" theory, that the sperma contains an animalcule or a little human already formed and waiting simply to grow.(18) Aristotle is trying to contend with these on his way to establishing his own claims about the nature of the generative fluids.
Darwin's proposal went by the curious name pangenesis