1888 - 89 .] Mr J. A. Thomson on Theory of Heredity. 103 
J tiger regards the continuity in cellular terms. It is a proto- 
plasmic continuity effected after the ordinary fashion of cell-division. 
To this there has to he added his chemical conception of pangenesis, 
which when expressed in more modern phraseology is reasonable 
enough — being simply the supposition that characteristic anastates 
and katastates find their way to the reproductive elements, and 
make these to some limited extent still sharers in the general life of 
the organism. 
Galton does not make the continuity much more precise than is 
implied in the general statement that a residue of the germs, gem- 
mules, or organic units in the “stirp,” remaining latent in the con- 
struction of the body, are passed on into the reproductive elements, 
and keep up a continuity between “ stirp” and “ stirp.” In regard 
to the future history of the gemmules, Galton supposes that they 
form groups in the ovum, and become directly associated with 
its division, while at later stages they wander and give rise to new 
cells. To obviate histological difficulties, Herdman proposes the 
following reasonable amendment, “that the body of the new in- 
dividual is formed, not by the development of gemmules alone and 
independently into cells, but by the gemmules in the cells causing, 
by their affinities and repulsions, these cells so to divide and redivide 
as to give rise to new cells, tissues, and organs.” All this admits of 
more direct expression in terms of “chemical pangenesis.” Brooks 
and Nussbaum rest satisfied in maintaining a cellular continuity. 
What keeps up the continuity, according to Weismann, is the 
Iceimjplasma, i.e ., a special portion of the nuclei of the reproductive 
cells, which with great morphological stability keeps itself intact, 
and is sooner or later once more established in the reproductive 
cells of the growing organism. Ntigeli finds sufficient explanation 
of the constancy of inheritance in the individuality and persistence 
(Beharrungsgesetz) of what he calls the “ idioplasma.” 
Kolliker, 0. Hertwig, Strasburger, and Bambeke may be noted for 
the emphasis which they have laid upon the nuclei as transmitting 
or rather continuing the essential characteristics from generation to 
generation. Thanks to the researches of such investigators as Van 
Beneden and Boveri, it is now certain that the male and female 
nuclei contribute an equal share in forming the segmentation nucleus 
of the ovum. Nay more, each of the first two daughter-cells has in 
