BOTANY 153 



a lowly bit of living green dust forces with compelling interest 

 upon the attention of the botanically minded. 



Nearly all the fundamental problems of botany here 

 present themselves, and find a concrete illustration. More- 

 over, it is clearly evident that if we attempt their solution we 

 must enlist the help of other sciences. To explain the shape 

 of the plant, how the shape is maintained, and how an ex- 

 change is effected between the solutions within and without ; 

 to explain the transformations of energy involved in all the 

 vital functions we must call upon physics. To understand 

 how the inorganic chemical compounds are transformed into 

 organic compounds for the nutrition of the plant we must 

 apply the principles of chemistry. To answer the question 

 of how the plant adjusts itself to its surroundings we must 

 understand the environment, and this involves, among other 

 things, a knowledge of meteorology. And, above all, to 

 understand how to proceed aright in the ascertainment of 

 botanical truth we must regard the laws of right thinking. 



To be sure the problems of botany do not always present 

 themselves to us reduced to their lowest terms, as in the study 

 of Pleurococcus. In some multicellular plants, for example, 

 the cells containing the green color are not the ones that 

 take in water. The green ones need to be lifted up and 

 exposed to the light as well as possible; the others need to 

 be in the soil where water is abundant, and hence arises a 

 necessity for a third set of cells to connect the first two. 

 Thus we have a lily or a tree. Reproduction becomes com- 

 plex, sexual differentiation is introduced, and eventually we 

 have a flower, followed by fruit and seed. Exposure to dry 

 air calls for protective structures which would be superfluous 

 in aquatic plants. But the essence of botany, in method and 

 content, is before us in our discussion of Pleurococcus vul- 

 garis. 



A clear understanding of method is fundamental to all 

 else. It is fundamental in the successful pursuit of botany 



