386 MR. W. AND MISS A. BATESON ON FLORAL VARIATIONS 
On Variations in the Floral Symmetry øf certain Plants having 
Irregular Corolla. By W. Barkson, Fellow of St. John’s 
College, Cambridge, lately Balfour Student, and ANNA 
Bateson. (Communicated by Francts Darwin, M.B., 
F.R.S., F.L.S.) 
[Read 2nd April, 1891.] 
(Prarzs L. & LI.) 
INTRODUCTION. 
Tur following observations, which we propose to extend, are 
put forward as a contribution to a study of the nature of the 
variations by which irregular forms of corollas are, or may be, 
produced. As to the causes which have operated in the pro- 
duction of these variations, we offer no suggestion: until a much 
fuller knowledge of the modes of Variation shall have been 
attained, discussion of the causes of Variation, or even curiosity 
concerning them is, in our judgment, premature. 
As a problem in Evolution, the nature of the changes by 
which irregular corollas come into existence is especially in- 
teresting. It is, of course, well known that there is in the case 
of many irregular flowers strong evidence that their peculiar 
forms are adapted to the process of cross-fertilization by par- 
ticular insects, or otherwise. From this evidence it is naturally 
expected that the same is true generally for irregular corollas. 
This conclusion leads in turn to the deduction that the evolu- 
tion of the forms of irregular corollas, as we know them, has 
occurred in connexion with their adaptation to the purposes 
of cross-fertilization, and that their perfection and persistence 
have consequently been achieved by the agency of Natural 
Selection. 
As to the exact steps by which such a process may have 
occurred, we have no knowledge or even plausible surmise. All 
that we ean affeet to know is that each form, like other forms of 
living things, is a term in a series of Variations, but as to the 
nature and magnitude of the integral steps between successive 
terms there is no direct evidence. Nevertheless, to obtain such 
evidence is absolutely necessary before any successful attempt to 
get an insight into the working of Evolution can be made. If 
