338 REV. GEORGE HENSLOW ON THE 
but in G. molle it matures it before that whorl, and is therefore proterogynous; and 1 
these stages correspond exactly with the decreasing size of the corollas. | 1 
Scrophularia nodosa is proterogynous and has a very small flower when compared 1 
with the conspicuous forms of Digitalis and Linaria &c., which are very strongly pro- j 
terandrous. Armeria Statice and Plantago, whose corollas rapidly dry up and become ` 
scarious, would seem to allow of nourishment being soon directed into the pistil, which q 
in these genera is decidedly proterogynous. The same remark applies to the Juncacee. 1 
Asarum and Aristolochia, again, as also some plants of Corylus Avellana, are protero- d 
 gynous, this last clearly showing that it is not solely due to such a compensatory 4 
process as I have supposed, though it may be still a question of.nutrition. Arum, Pota- q 
mogeton, Triglochin, and Paris are ‘all proterogynous and inconspicuously flowering 1 
plants. On the other hand, Colchicum is said to be proterogynous, though bearing a. 1 
large flower, but Butomus is proterandrous. Lastly, Prunus spinosa and Padus, as well 7 
as Orategus oxyacantha, are proterogynous. Perhaps the lateness of the season in which 1 
Colchicum flowers, and the earliness in spring when the genus Prunus is in bloom, may | 
account for the comparative delay in the stamens, thus bringing about a relatively | 
earlier development of the pistil, resulting either in self-fertilization or proterogyny. 1 
"Finally, I would observe that the causes which may bring about self-fertility appear ` 
to be very complicated, and that very likely no one cause stands alone. Therefore, while 1 
I have enumerated what I could designate prowimate causes, yet they may be perhaps: 4 
better regarded as correlative phenomena than as being so many distinct causes. The | 
primary or fundamental cause (both of them, e. g. loss of colour and of self-fertility) - 
lies apparently too deep for discovery in the constitution of the entire plant. We must, 
however, be on our guard against interchanging causes and effects. It is one thing to 
say that continued self-fertilization may bring on a deterioration in the constitution 
(which, I think, is not proved to be the case), another thing to believe that a seemingly 
less vigorous condition of vegetative growth may induce a return to self-fertility i in dicho- 
gamous and other flowers, such being in some cases, I believe, the real interpretation. 
The intimate relationship between vegetative and reproductive vigour is too well 
known to require any elucidation; and all I would add to that compensatory process is, 
that in proportion as the former is lessened so does the return to self-fertilization follow, 
that being the special form of reproductive energy which, I believe, Nature vmm strives 
 toregain. (See also Anim. and Pl. under Domest. ii. p. 163.) 
. Moreover, it must be borne in mind that great vegetative * vigour' is not NAR 
a good sign of any lasting benefit to the plant, just as giants among men are often. 
not so well favoured by nature as men of mean height. 
This idea of the existence of a compensatory process between the outer whorls e 
the pistil is further countenanced by an analogous one between the ovary and the seed. 
An interesting and important paragraph by Mr. Berkeley illustrates this fact so well that 
I quote it in full from the * Gard. Chron.’ (1855, p. 36) :— 
PTT 
* Though all the parts of a plant may be perfect, and impregnation may take place, and an embryo ! be 
formed, the plant may be WE from constant abortion. This is especially the case where the — of 
