HERBARIA IN THEIR RELATION TO BOTANY. 363 



and it is their object to show us at all times not only the plants 

 described, but also the family relation between these different 

 plants. 



In Linnreus's time a botanist was regarded as somebody who 

 could name at sight any plant presented to him, and the best 

 botanist was the one who was most proficient in this. We are 

 justified, however, in requiring a few other things from a good 

 botanist. The recognition of the family relations between differ- 

 ent plants gave rise to the comparing of their different organs, to 

 the study of their development, to inquiring what conditions had 

 influenced an organ in such a way that it became modified, to 

 the search for the equivalents of the organs of the higher plants 

 among the lower ones ; all of which constitute that branch of 

 botany which now is known as morphology. 



The recognition of yet finer details created our histology. 



The closer acquaintance with plants induced scientific men to 

 observe their habits, their distribution, and how they lived ; and 

 this is plant physiology in its widest sense. 



For the study of the botanical system, morphology, and geog- 

 raphy, a herbarium like that of Captain Smith is of the greatest 

 advantage. For physiological purposes, quite other things as 

 exact instruments, hothouses to keep living plants, etc. are 

 necessary. 



Physiology is that part of botany which has had most practical 

 value. The fertilizing with artificial manures is entirely founded 

 upon it, for it never could have become known if careful experi- 

 ments in the laboratory had not shown what substances were 

 necessary to each particular kind of plant. Consequently, all 

 agricultural experiment stations are practically based on plant 

 physiology. 



This plant physiology, or the science of the normal life of the 

 plant, gave rise to the study of the plant under abnormal in other 

 words, diseased conditions, and so the science of plant pathology, 

 on which our knowledge of the diseases of our crops and the way 

 to prevent or cure them is based. 



Last, and not least, the study of those very smallest plants, the 

 bacteria, made an enormous change in our treatment of sick 

 human beings ; the study of the parasitic molds has done an im- 

 portant service to our fish industries ; so the influence of mod- 

 ern scientific botany is felt in fields that seem to the casual 

 observer to have no connection with vegetation, and the scope 

 of this science is no longer confined to what for years was its 

 only object the naming of plants. 



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