18431882] MORPHOLOGY 415 



wonderful how well Forbes stands it. What a very striking Letter 320 

 fact is the botanical relation between Africa and Java ; as 

 you now state it, I am pleased rather than disgusted, for it 

 accords capitally with the distribution of the mammifers l : only 

 that I judge from your letters that the Cape differs even more 

 markedly than I had thought, from the rest of Africa, and 

 much more than the mammifers do. I am surprised to find 

 how well mammifers and plants seem to accord in their 

 general distribution. With respect to my strong objection to 

 Aug. St. Hilaire's language on affaiblisseinent? it is perhaps 

 hardly rational, and yet he confesses that some of the most 

 vigorous plants in nature have some of their organs struck 

 with this weakness he does not pretend, of course, that they 

 were ever otherwise in former generations or that a more 

 vigorously growing plant produces organs less weakened, and 

 thus fails in producing its typical structure. In a plant in a 

 state of nature, does cutting off the sap tend to produce flower- 

 buds ? I know it does in trees in orchards. Owen has been 

 doing some grand work in the morphology of the vertebrata : 

 your arm and hand are parts of your head, or rather the 

 processes (i.e. modified ribs) of the occipital vertebra ! He 

 gave me a grand lecture on a cod's head. By the way, would 

 it not strike you as monstrous, if in speaking of the minute 

 and lessening jaws, palpi, etc., of an insect or crustacean, any 

 one were to say they were produced by the affaiblissement of 

 the less important but larger organs of locomotion. I see 

 from your letter (though I do not suppose it is worth referring 

 to the subject) that I could not have expressed what I meant 

 when I allowed you to infer that Owen's rule of single organs 

 being of a higher order than multiple organs applied only to 

 locomotive, etc.; it applies to every the most important organ. 

 I do not doubt that he would say the placentata having single 

 wombs, whilst the marsupiata have double ones, is an instance 

 of this law. I believe, however, in most instances where one 

 organ, as a nervous centre or heart, takes the places of several, 



1 See Wallace, Geogr. Distribution, Vol. I., p. 263, on the "special 

 Oriental or even Malayan element " in the West African mammals and 

 birds. 



2 This refers to his Lemons de Botanique (Morphologic Vegetale), 

 1841. Saint-Hilaire often explains morphological differences as due to 

 differences in vigour. See p. 413. 



