454 Tricotylons Races. 
thera (Knciffia) ylauca in 1899, but counted 5% tri- 
cotyls, both on the phosphate and on the nitrate half. 
I obtained the same result in Scrophularia nodosa by 
growing one half in ordinary garden soil and the other 
in sand, both yielding \% (1894). 
The two first experiments on the influence of manure 
show that an increase in the number of tricotyls is as- 
sociated with a diminution of the yield. The same result 
can also be obtained if the harvest of the individual plants 
is reduced in other ways. In Oenotlicra hirtclla I adopted 
two methods of doing this, late sowing and culture in 
pots throughout the whole summer. Tricotylous seed- 
lings of a single parent (with 66%) were planted out. 
In one of the two groups the sowing had taken place in 
March, in the other at the beginning of May (1898). 
Some plants of the former sowing were kept in pots of 
15 centimeters filled with well-manured garden soil 
throughout the whole summer. Fertilization took place 
in parchment bags and the individual crops, recorded and 
evaluated in the usual way, gave the following result : 
HEREDITARY VALUES IN OENOTHERA HIRTELLA IN 1898. 
Percentage values 10 20 30 40 50 60 70 Mean 
Normal culture 1 4 4 3 5 1 37 '; 
After sowing in May 10 14 11 1 41'; 
After culture in pots 3 5 7 4 047% 
Number of plants experimented with 18, 36 and 1'). 
We see therefore in this case a definite though small 
increase in the number of tricotyls. The mean of the 
harvest for the normal culture was 3.5 cc., for the late 
culture 2.5, for the pot-culture 4.5 cc. This latter had 
therefore not had the expected result of making the 
yield smaller, and as, nevertheless, the proportion of 
