518 
The Ohio Naturalist. 
[Vol. XV, No. 7, 
SUMMARY. 
The normal hereditary mechanism then of the chromosomes 
acts as follows: 
1. The chromosomes normally function as individuals and are 
segregated as such at each karyokinesis. 
2. The chromosomes do not conjugate or fuse, nor does their 
material mix in the fertilization stage; but each chromosome is 
carried thru the zygote stage of the organism as a definite indi¬ 
vidual. 
3. In the reduction division, the chromosomes show them¬ 
selves to be definitely paired; and the 2x number of the zygotic 
individual represents two definite sets or complements of chromo¬ 
somes, each one of the one set having its corresponding synaptic 
mate in the other. A specific attraction develops between each 
pair of synaptic mates during the prophases of reduction resulting 
in an end to end fusion in pairs and a subsequent folding side by 
side, so that a bivalent chromosome represents synaptic univalents 
fused longitudinally at least in the ordinary elongated types of 
chromosomes. 
4. The segregation of the univalents during reduction is 
according to the law of chance; therefore, each daughter cell 
receives a full (x) complement of univalents, some of the set being 
descendants of those brought into the zygote by the parent egg 
and some by the sperm. 
5. These processes are in harmony with the observed phenom¬ 
ena of Mendelian heredity. 
CORRECTION 
The list of Insect Galls of Cedar Point (Ohio Naturalist, 
December, 1914) is in error as follows: 
P. 3S1—Andricus futilis O. S. should doubtless be Dryophanta 
papula Bassett. 
P. 382- Holcaspis globulus Fitch was found on Quercus 
macrocarpa instead of Q. imbricaria. 
I am indebted to Mr. L. H. Weld of Evanston, Ill., for these 
corrections. 
Paul B. Sears. 
