ZOOLOGY: E. G. CONKLIN 
101 
An elliptical distribution of stars is not confined to the Hercules 
cluster. Counts for four other systems are summarized in Table III 
and plotted in figure 3. Three of them show unmistakable signs of 
elliptical form; the fourth, Messier 10, is a cluster with noticeably- 
less condensation toward the center than usual. If the axes of sym- 
metry in the others represent the projections of galactic-like planes, 
it is possible that in Messier 10 there is such a plane of symmetry in- 
clined nearly 90° to the line of sight. The inclination to the equator 
of the projected major axis of Messier 13 is 152° (angle counted from 
Following through North), For Messier 2 and N. G. C. 5024 the in- 
clination is 133° and 105°, respectively, while for Messier 15, which 
is across the Milky Way, it is 60° and is nearly parallel to the galactic 
plane. 
* A bibliography of the more important of these investigations is given in Mt. Wilson 
Contrih. No. 115, (3-10), and No. 116, (4-8). 
2 Bailey, S. I., Cambridge, Ann. Ohs. Harvard Coll., 76, (43-82). 
3 Shapley, H., Observatory, London, 39, 1916, (452-456). 
4 Bailey, S. I., Astr. and Astroph., Northfield, Minn., 12, 1893, (689-692). 
^Washington, Carnegie Inst., Year Book, 12, 1913, (213); 13, 1914, (258). 
THE SHARE OF EGG AND SPERM IN HEREDITY 
By Edwin G. Conklin 
DEPARTMENT OF BIOLOGY. PRINCETON UNIVERSITY 
Read before the Academy November 13. 1916. 
L Assumed Equivalence of Inheritance from Both Parents. — Practi- 
cally all students of heredity are agreed that there is a general equivalence 
of inheritance from father and mother, and 0. Hertwig (1892) cites 
this as one of the evidences that the chromosomes only contain inheri- 
tance material, or 'Erbmasse,' since they alone come in approximately 
equal volumes from the two parents. Indeed phenomena of Mendelian 
inheritance demonstrate that, with respect to those characters which 
usually distinguish the two parents, there is equivalence of inheritance 
from each, and where offspring resemble one parent more than the other 
they are probably as frequently patrocHnous as matroclinous. Further- 
more, the distribution of chromosomes in maturation, fertilization and 
cleavage is exactly parallel to the distribution of Mendelian factors, 
which practically demonstrates that the chromosomes are the seat of 
these factors. 
This conclusion has led many students of heredity to regard the cyto- 
plasm of the germ cells as of no significance in heredity. Both egg and 
sperm contain cytoplasm which is differentiated, in the former for the 
