1044 The American Naturalist. [ December, 
sive calculation, not necessary to reproduce here, Galton found that 
the totality of the ancestors of each T-grandparent determines the tri- 
color character of 4 per cent. of the progeny, and all the ancestors of 
each N-grandparent determines the T-characters of 2 per cent. of the 
progeny, so we must add to our sum 34 per cent.=12 per cent. for 
the 3 T-grandparents and 2 per cent. for the N-grandparent which 
gives the grand total of 68.7-+-12-++-2=83 per cent. of the 119 progeny 
(or 99 individuals) which should be tricolor. Asa matter of fact of 
_ the 119 individuals which had the ancestry in question 101 individuals 
were tricolor. Many comparisons between calculations and observa- 
tions were made which agreed as well as this and thus confirmed the 
truth of the conclusion that we inherit on the average one-half of our — 
qualities from our parents and half the remainder from each successive 
earlier generation of ancestors.—C. B. D. 
Preformation vs. Epigenesis.—That the modern revival of the 
preformation—epigenesis controversy is resulting in a harmonious 
middle position through the application of the experimental method is 
a source of gratification as well to the believers in the application of 
this method to embryology as to those who desire the settlement of the 
dispute. Incidentally, however, these experiments are giving a clearer 
insight into the form-producing and form-maintaining factors. One of 
the latest contributions of this sort is that of Crampton who has de- 
scribed in the Annals of the New York Academy of Seiences, Volume 
X, experiments on isolated blastomeres of the Ascidian Molgula man- 
hattensis. He finds that here, much as in the sea-urchin, the one-half 
blastomere undergoes a strictly partial cleavage, but rearrangements of 
blastomeres soon occur which tend to mask the partial nature of the 
development. Eventually a nearly complete larva of less than normal 
size and with defects in certain organs is produced. The missing half 
has been supplied by the cells already present. Thus there is here no 
pure epigenesis, no strict preformation, but a remarkable regulation 
phenomenon, as Driesch would say, by which the mutilated organism 
attempts, but. not altogether successfully, to develop normally despite 
the unfavorable conditions. 
Dissemination of organisms.—Experiments of Dr. Amedeo 
Berlese showing how insects and especially ants and some species of 
flies aid in the diffusion, preservation, and multiplication of yeasts, are 
described in a recent number of Nature.’ 
2 Nature, Oct. 14, 1897, pp. 575-577. 
