134 CANNON: STUDIES IN PLANT HyBrRIDS 
a strong support to the idea of sex in plants, andalso pointed the 
way to the true conception of fertilization. 
In addition K6lreuter, in the course of his long career as a 
hybridizer, arrived at other results that were of almost equal im- 
portance. For instance, he first pointed out the meaning of the 
visits of insects to flowers, and thus formed the basis for Sprengel’s 
subsequent work, and he first showed the significance of nectar 
in this connection.* K6lreuter also introduced the ‘‘ modern”’ 
methods in experimental research, as a single illustration taken 
from many will suffice to show. He had the mistaken idea that 
the part of the pollen necessary to insure fertilization was the fluid 
which he had observed about it and which he supposed originated 
in the interior of the grain and oozed out through the pores. He 
therefore was interested to learn how many grains were required 
to effect fecundation. To ascertain this he counted the grains in 
a flower and artificially pollinated with a varying but a known 
number. In Aidiscus Trionum he counted 4,863 grains, and 
found that only 50-60 were necessary to fructify more than 30 
ovules. In Miradilis Jalapa and M. longiflora two or three, or 
only one were required to fertilize the single ovule. 
K6lreuter recognized all of the important characteristics of 
plant hybrids.+ He learned that species-hybrids were as a rule 
intermediate and uniform, whichever race provided the male or 
female parent. He observed the fruitfulness of variety-hybrids, 
the sterility or lessened fruitfulness of those between species, the 
stronger growth of many hybrids and other phenomena. __ In his 
experiments K6lreuter used mainly the following genera: Agui- 
legia, Matthiola, Dianthus, Melandrium, Linum, Malva, Lavatera, 
Lobelia, Nicotiana, Datura, Lycium, Verbascum, Digitalis and Mira- 
bilis. 
About the time that K6lreuter was engaged in. the expeti- 
mental study which gave such remarkable results, Linné, ignoring 
that scientist’s work, put forward theories in which hybrids played 
a prominent role. And this was done with hardly any expeti- 
-mental basis for his ideas. I refer to Linné’s hypotheses regard- 
ing the origin of genera and species. According to Sachs (4 ¢ 
* Sachs, Geschichte der Botanik, 440. 1875. 
. | Focke, Die Pflanzen-Mischlinge, 431. 1881. 
