1879] TRANSACTIONS. 9 



then planted therein a willow, which weighed just five pounds. 

 The soil was enclosed by a cover so that no dust from outside 

 could reach it ; and it was kept moist with enough water, as 

 occasion required, for five years. At the end of that time, the 

 willow was removed, and the soil separated carefully from the 

 roots. The willow weighed, then, one hundred and sixty-four 

 pounds ; but the soil, again thoroughly dried, as at first, had 

 lost only two ounces ! Although the experiment was not con- 

 ducted with the exactness which characterizes modern research, 

 it was a very excellent one for the time in which it was performed. 

 It must be added that Van Helmont erroneously concluded 

 that the plant had taken all its nourishment from the water, 

 whereas we know to-day that the plant obtains from the atmos- 

 phere a large part of the material out of which its structure 

 is made." 



[The relations of the soil and other surroundings to the successful treat- 

 ment of garden plants and orchard trees, occupied much of the lecturer's 

 attention at this stage of the course.] 



II. From Flower to Seed. 



This completes the cycle of plant-life. 



"A flower is a branch, with leaves for the production of seeds. 

 It is easy to find fault with every definition of so diversified a 

 mechanism as a flower, but the definition just given will answer 

 our present purpose very well. 



A flower is a mechanism for the production of seeds. All 

 parts, therefore, which are directly concerned in the production 

 of seeds, must be taken into account. Even the floral leaves 

 or bracts, which are only indirectly tributary to the formation 

 of seeds, must be regarded. The outer circles, the calyx and 

 corolla, are generally termed unessential, because they are fre- 

 quently merely protective, while the stamens and the carpels 

 are the essential parts. The carpels contain the ovules, which 

 are to become seeds ; the stamens furnish the pollen, by the 

 indirect action of which this change is to be brought about. 

 Therefore, we might regard the ovules and the pollen as the 

 only essential parts in the production of seeds. Each stamen 

 consists of an anther, which is often supported upon a filament, 

 or slender thread. ' The anther is a sac filled with pollen, which 

 most generally is like fine dust, but which is shown by the 

 2 



