60 THIRD REPORT — 1833. 



in this way their original position, and the face which had ori- 

 ginally been tlie uppermost, immediately became covered with 

 stomata. It, therefore, appears that the impulse once given, 

 the predisposition to assume particular appearances or func- 

 tions is absolutely fixed, and will not change in the ordinary 

 course of nature. This is a fact of very high interest for 

 those who are occupied in researches into the causes of what is 

 called vegetable metamorphosis, an expression which has been 

 justly criticised as giving a false idea of the subject to which 

 it relates. 



Morphology. — When those who first seized upon the im- 

 portant but neglected facts out of which the modern theory of 

 moi'phology has been constructed, asserted that all the appen- 

 dages of the axis of a plant are metamorphosed leaves, more 

 was certainly stated than the evidence would justify ; for we 

 cannot say that an organ is a metamorphosed leaf, which in 

 point of fact has never been a leaf. What was meant, and that 

 which is supported by the most conclusive evidence, is, that 

 every appendage of the axis, whether leaf, bractea, sepal, petal, 

 stamen, or pistillum, is originally constructed of the same ele- 

 ments, arranged upon a common plan, and varying in their 

 manner of development, not on account of any original differ- 

 ence in structure, but on account of special and local predis- 

 posing causes : of this the leaf is taken as the type, because it 

 is the organ which is most usually the result of the develop- 

 ment of those elements, — is that to which the other organs 

 generally revert, when from any accidental disturbing cause 

 they do not assume the appearance to which they were originally 

 predisposed, — and, moreover, is that in which we have the most 

 complete state of organization. 



This is not a place for the discussion of the details upon 

 which the theory of morphology is founded ; it is sufficient to 

 state that it has become the basis of all philosophical views of 

 structure, and an inseparable part of the science of botany. Its 

 practical importance will be elucidated by the following circum- 

 stance. Fourteen or fifteen years ago I was led to take a 

 view of the structure of Reseda very different from that usually 

 assigned to the genus ; and when a few years afterwards that 

 view was published, it attracted a good deal of attention, and 

 gained some converts among the botanists of Germany and 

 France. It was aftei'wards objected to by Dr. Brown upon 

 several grounds ; but I am not aware that they were considered 

 sufficiently valid to produce any change in the opinions of those 

 who had adopted my hypothesis. Lately, however, Professor 



