Tricotyls, Hemi-tricotyls, and Tetracotyls. 363 
laria nodosa produced, in the harvest of 1894, a mean 
of 2% and a maximum of 5.5% tricotyls per seed-parent. 
I harvested the seeds from two tetracotyls and obtained 
0.5% and 3% tricotyls. Amongst the 2000 seedlings 
which these cultures contained, there were 30 tricotyls, 
3 hemi-tricotyls and only 2 tetracotyls. 
On the other hand a tetracotylous plant of Asperula 
azurca gave 7% and the corresponding tricotylous seed- 
parents only 2%, in 1892. Of this 7%, there were 5% 
tricotylous, 1% tetracotylous, and 1% hemi-tricotylous. 
I bred the tetracotyls of Amarantus spcciosus for two 
generations, in 1893 and 1894. In the summer of 1893, 
9 tetracotylous plants were left to flower ; 3 proved to be 
fasciated, but the rest gave values varying from 1 to 
7.5% with a mean of 5%. I counted for each seed- 
parent 500-1000 seedlings. The corresponding tricotyl- 
ous culture gave values from 2.5% to 7.5%, that is, a 
mean of 4.5%; from each of the 15 seed-parents from 
700 to 1000 seedlings being examined. We see there is 
practically no difference between the two cases. Together 
the tetracotylous parents produced only 6 tetracotylous 
offspring among 4000 seedlings, and the tricotyls 13 
among 10,000; that is to say, they behaved in regard 
to this character as variants of the same race. I then 
selected the tetracotylous offspring of the tetracotylous 
seed-parents for a continuation of the race in 1894, but 
observed no further progress, the percentage in tetra- 
cotyls being only 0.2%. 
The question suggests itself whether the proportion 
of tetracotylous seedlings, perhaps, simply obeys the laws 
of probability. The splitting of a cotyledon may be im- 
agined to be distributed at random over a group of say 
100 individuals, and we may ask, how many times a 
