Tricotylous Half Races. 391 
through the course of four generations (1891-1894), 
and found it heritable to the extent of from 1 to 2%, 
but I have not made any detailed records. 
Spinacia olcracca. The spinach also contains tri- 
cotylous seedlings. I employed the Dutch spinach with 
smooth round seeds without thorns, a fine and perfectly 
constant type. In 1892 I found a tricotylous specimen, 
and grew this amongst some normal plants, because the 
species is dioecious. When the harvest was first exam- 
ined there proved to be five tricotyls and one hemi-tricotyl 
amongst 1000 seedlings, i. e., 0.6%. Then the best tri- 
cotyls were selected from several thousand seedlings ; 
thirteen being met with. During the flowering period, 
several of them proved to be monoecious, a phenomenon 
which sometimes occurs in this species and has been ob- 
served also in Cannabis saliva, Mercurlalis anmia, and 
others. I harvested the seeds separately from 5 female 
or monoecious plants, and obtained ratios of 0, 0, 0, 1 and 
2% tricotyls amongst the seedlings, of which only 4 
managed to flower. They were one male and 3 female 
plants which latter set an abundance of seed. They gave 
ratios of 0, and 2%, the latter occurring amongst 430 
seedlings. In the summer of 1895 the tricotyls flowered, 
and I collected the harvests of the various female plants 
separately, and thus was able to determine the proportion 
of tricotyls for each parent in the spring of 1896. This 
fluctuated between and 3% and in one case reached 
4% (mean 1.5%). 
Summary: The results of the experiments described 
show that, in the cases dealt with, a stringent selection, 
extending over three years, failed to effect any definite 
and certainly any considerable advance. The individual 
instances fall into two categories ; as a rule the propor- 
