KOLREUTER 151 



ticular flower, so that, if he had had any hint of the 

 actual microscopic processes of fertilization, he would 

 have been quite prepared for the more fundamental 

 discovery. 



Kolreuter, indeed, believed that the act of fertiliza- 

 tion consisted in the intimate mingling together of two 

 fluids, the one contained in the pollen-grain, and the 

 other secreted by the stigma of the plant. The mingled 

 fluids, he supposed, next passed down the style into 

 the ovary of the plant, and arriving at the unripe 

 ovules, initiated in them those processes which led to 

 the formation of seeds. In this belief Kolreuter simply 

 followed the animal physiologists of his time, who 

 looked upon the process of fertilization in animals as 

 taking place by a similar mingling together of two 

 fluids. Now that we know that fertilization consists 

 essentially in the intimate union of the nuclei of two 

 cells, one of which, in the case of plants, is the ovum 

 contained within the ovule, whilst the other is repre- 

 sented by one of a few cells into which the contents 

 of the pollen-grain divide, we can understand more 

 clearly the bearing of Kolreuter 's observation. And 

 it is greatly to this eminent naturalist's credit that he 

 succeeded in carrying out his observations with so 

 much accuracy, when the full meaning of those 

 observations was of necessity hidden from his com- 

 prehension. 



Kolreuter was the first to observe accurately the 

 different ways in which pollen can be naturally con- 

 veyed to the stigma of a flower. This may take place 

 either by the pollen-grains falling directly upon the 



