SELF-FERTILIZATION OF PLANTS. 361 
become morphologically self-sterile here, had, where Mr. Meehan observed it, slightly 
changed, and so recovered its self-fertilizing powers, as was the case with -Eschscholízia. 
T. arvense and T. procumbens, and, I would add, 7. minus, appear to be highly self-fertile, 
according to Mr. Darwin, though he suspeets the latter may be visited by small nocturnal 
moths. With regard to 7. minus, the order of development, viz., calyx, pistil, stamens, 
corolla, agrees with self-fertilizing plants, 
Medicago sativa. This plant, when protected, yielded seeds, as compared with unpro- 
tected, in the ratio of 101:.77. Hence it is highly self-fertile, though specially modified, 
in having * irritable" stamens, for cross-fertilization (note, p. 360). 
M. denticulata. This species appears to be quite self-fertile. The position of the 
anthers clustering round the stigma is seen in Tab. XLIV. fig. 15. 
Phaseolus vulgaris. While this species is quite self-fertile, P. multiflorus, when ** pro- 
tected from insects, produced on two occasions about one third and one eighth of the 
full number of seeds... .. The flowers are not visited by insects in Nicaragua; and, 
according to Mr. Belt, the species is there quite sterile." Cross and Self-Fert. p. 200 (Zhe 
Naturalist in Nicaragua, p. 10. See also a paper by myself in Gard. Chron. Nov. 3, 1878.) 
Lathyrus grandiflorus is in'this country more or less sterile. It never sets pods 
unless the flowers are visited by humble-bees, or artificially fertilized. L. odoratus and 
LL, Nissolia are fully self-fertile. 
^ Pisum sativum is also fully self-fertile. 
Vicia faba. Unprotected plants were between three and four times more fertile than 
the protected plant. Vicia sativa and V. hirsuta are both perfectly self-fertile. 
The above cases, mainly taken from Mr. Darwin’s lists of sterile and self-fertile plants, 
seem to bring out the following facts :—(1) Conspicuous papilionaceous flowers may be 
absolutely self-sterile, or only partially so, or not at all Whether any species are 
physiologically self-sterile I am not sure; but many are certainly more or less morpho- 
logically, as Lupinus, sp., Phaseolus multiflorus, &c. (see * Cross and Self-fertilisation,' 
pp. 150, note, and 152). (2) One species of a genus may be highly self-fertile, while 
another species may be barren (Phaseolus and Trifolium). Even with regard to the self- 
sterile P. multiflorus, Mr. Darwin found that “the advantage gained by a cross is very 
small" or, practically, none, as the heights were as 100 : 96, and there was little or no 
difference in their fertility. 
The Sweet Pea, though crossed in the south of Europe, is entirely self-fertile in this 
country, though L, grandiflorus is self-sterile ; on the contrary, L. odoratus and, we may 
add, P. sativum, appear rather to agree with Phaseolus vulgaris in being plants which have 
become] highly self-fertile by being transformed from warmer climates to this country. 
If so, they exactly parallel the case of Eschscholtzia, which was actually proved to be so. 
From these intermediate stages we pass to species which are as fertile when unvisited as 
when fertilized by bees and other insects. Lastly, there are extremely small-flowered 
species, but with perfect blossoms, which are probably never visited, as Vicia hirsuta ; and 
also several with cleistogamous flowers, which are, as is always the case, highly self-fertile. 
- Mr. Darwin’s descriptions of several cleistogamous flowers (‘Forms of Flowers,’ 
P. 310 seqq.) are particularly interesting, as they so manifestly prove these closed 
