8 



II. The Evolution of Fruits. 

 By Professor G. S. Boulger, F.L.S., F.G.S. 



[Abstract of Discourse delivered viva voce, February 26th, 1881.] 



Syllabus. — The Descent Theory. — Definition of the word "Fruit." — 

 Origin of fruits. — Marginal plaeentation. — Object of fruits. — Possible 

 cause of the variability of the fruit. — Generalizations as to the course of 

 variation in fruits. — Ontogeny of the fruit. — The phylogenetic importance 

 of the fruit, and the results of the study of the fruit on the phylogenetic 

 classification of flowering plants. 



One of tlie strongest confirmations of the Descent Theory 

 is its vital energy. It is not only consistent with hosts of 

 ever- accumulating facts in every department of Biology, but 

 it is constantly suggesting new lines of inquii'y to which it 

 forms the only key. Thus, though in tracing the evolution 

 of the numerous kinds of fruit from the simplest and pre- 

 sumably earliest forms, it is necessary to assume this theory 

 as a working hypothesis, not the least important result of 

 the investigation will be the accumulation of much evidence 

 that by its self-consistence tends strongly to show that the 

 hypothesis truly represents the facts of Nature. 



Affixing the definite meaning to the word " fruit" of " the 

 whole of the (jyimcium which ripens in consequence of 

 fertilisation, together with all surrounding accrescent or 

 succulent parts, originating from a single flower," — a 

 definition free from many of the objections which attach to 

 Sachs' use of the word for each apocarpous carpel, — we find 

 nothing really analogous to a fruit among cryptogamic 

 plants. The highest degree to which secondary sexual 

 organs are developed in these groups only amounts to the 

 formation of a seed. It is among the Gymnosperms that we 

 have the nearest approach to the origin of the fruit. 



Without concerning ourselves with the cognate but distinct 



