VoL. 29 No. 12 
BULLETIN 
OF THE, 
TORREY BOTANICAL CLUB 
DECEMBER, 1902 
A cytological Basis for the Mendelian Laws 
By WILuiamM AusTIN CANNON 
In the decade following the year 1860, Gregor Mendel, an 
abbot of the Roman Church, experimented in the garden of his 
abbey i in Briinn with plant hybrids. This experience led him to 
results and conclusions now believed by students of heredity to be 
of great importance. These were published in the Verhandlung 
des Naturforschenden Vereins of Brinn and were lost to the view 
of scientists until their rediscovery about two years ago by de 
Vries, Correns, and Tschermak. The plants experimented with by_ 
Mendel were mainly species of Pisum, Phaseolus, and Hieracium, 
and, although the results were in a measure contradictory, those 
founded upon his pea experiments were uniform, and constituted the 
basis for his conclusions, namely, those expressed by the “ Men- 
delian Laws.” The essential conception of Mendel may be briefly 
Stated as follows : ; | 
When one pure form (A) is crossed vith another pure form (a) 
e hybrid of the primary cross shows the A characters only. 
n, however, the hybrid plants of this generation are fertilized 
among themselves and produce offspring the a characters are first 
Seen, and in a definite proportion to the form bearing the 4 char- 
cters, These constitute the hybrids of the second generation. 
f now the hybrids of the second generation are fertilized in sucha 
Manner that plants with a characters are crossed with those bear- 
the same characters, and likewise plants bearing the opposing 
la icters with forms like themselves, the resulting hybrids will 
I ve in a manner characteristic of the respective cross. That is 
he plants with a characters will be found to transmit those 
ara SB ilsy tee “fixed”; and (2) When the plants 
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