ifil Introduction. [Book III. 



set in motion, and it mattered not what the result might be. 

 In all questions connected with the phenomena of life, our own 

 life is not only the starting-point but also the standard of our 

 conceptions ; what animate nature is as opposed to inanimate 

 we discern first by comparing our own being with that of other 

 objects. From our own vital motions we argue to those of the 

 higher animals, which we comprehend immediately and in- 

 stinctively from their conduct ; by aid of these the motions 

 of the lower animals also become intelligible to us, and 

 further conclusions from analogy lead us finally to plants, 

 whose vitality is only in this way made known to us. While 

 plants were thus even in ancient times regarded as living 

 creatures and allied to animals, further reflection naturally 

 suggested the idea that the phenomena of animal life would 

 be reproduced in plants even in details. We learn from the 

 botanical fragments of Aristotle that this was in fact the way 

 in which the first questions in vegetable physiology arose j 

 they assumed a more definite form with Cesalpino, and later 

 physiologists repeatedly made use of similar conclusions from 

 analogy. The historian of this branch of botanical science 

 must seek no other beginning of it, for it had no other and 

 could have no other from the nature of the case. And if 

 preconceived analogies between plants and animals often 

 proved deceptive and mischievous, yet continued investigation 

 gradually brought to light more important and more essential 

 points of agreement between the two kingdoms ; it has be- 

 come more and more evident in our own days, that the 

 material foundations of vegetable and animal life are in the 

 main identical, — that the processes connected with nourish- 

 ment, movement of juices, sexual and asexual propagation 

 present the most remarkable similarities in both kingdoms. 



If the first founders of scientific vegetable physiology sur- 

 rendered themselves thoroughly to teleological views, this was 

 owing to the circumstances of the time, and it served indeed 

 to promote the first advances of the science. There was no 



