SIRKS, PRAE-MENDELISTISCHE ERFELIJKHEIDSTHEORIEEN. 329 
life, with some tendency to the earlier development of the inherited 
character.” (1888. II. p. 61). 
Dat waren voor DARWIN vaststaande regels, waaraan de erfelijk- 
heid onderworpen was, en voor die regels trachtte hij een ver- 
klaring te vinden door zijn bekende hypothese der pangenesis, 
die hij in hetzelfde werk aan zijn mede-onderzoekers ter discussie 
bood, daarbij uitdrukkelijk ziin hypothese als een voorloopige 
kenschetsend. Hij erkent dan ook, dat zijn hypothese uit een 
aantal veronderstellingen bestaat. „It is universally admitted that 
the cells or units of the body increase by self-division or prolife- 
ration, retaining the same nature, and that they ultimately become 
converted into the various tissues and substances of the body- 
But besides this means of increase I assume that the units throw 
off minute granules which are dispersed throughout the whole 
system; that these, when supplied with proper nutriment, multiply 
by self-division, and are ultimately developed into units like those 
from which they were originally derived. These granules may be 
called gemmules. They are collected from all parts of the system 
to constitute the sexual elements, and their development in the 
next generation forms a new being; but they are likewise capable 
of transmission in a dormant state to future generations and may 
then be developed. Their development depends on their union 
„with other partially developed or nascent cells which precede them 
in the regular course of their growth. Gemmules are supposed to 
be thrown off by every unit, not only during the adult state, but 
during each state of development of every organism; but not 
necessarily during the continued existence of the same unit. Lastly, 
I assume that the gemmules in their dormant state have a mutual 
affinity for each other, leading to their aggregation into buds or 
into the sexual elements. Hence, it is not the reproductive organs 
or buds which generate new organisms, but the units of which 
each individual is composed. These assumptions constitute the provi- 
sional hypothesis which I have called Pangenesis’ (1888 p. 369-370). 
Die pangenesis-hypothese is dus wel een heel gebouw van ver- 
onderstellingen, en het is dan ook zeker wel aan de oncontroleer- 
baarheid der in DARWINS tijd bekende feiten toe te schrijven, dat 
DARWIN in zijn gevolgtrekkingen niet gelukkiger is geweest. In 
twee opzichten verschilt ze van de opvattingen van SPENCER: 
