SEXUALITY IN PLANTS. 
367 
annihilation or obliteration of either sex. In a unisexual 
flower one sex, though not actually, may be at least potentially 
present — nay, must be, if Darwin’s theory of pangenesis be true 
— and so it happens that, when any change of conditions occurs, 
the heretofore latent gemmules start into life, and the uni- 
sexual is once more replaced by the bisexual state. In other 
words, a reversion occurs to the assumed primitive condition. 
There are numerous instances among one-sexed plants to 
prove that the missing organs are latent, rather than altogether 
deficient. It has already been stated that many one-sexed 
flowers are so by arrest of development ; the male or the female 
element, as the case may be, is present, but in a latent or 
rudimentary state. So many flowers which in the adult state 
are one-sexed, are in the young state structurally hermaphro- 
dite. Indian corn or maize, the two sexes of which are very 
distinct in the fully developed condition, is said to have pri- 
mordially bisexual flowers. A plant which in one year, or it 
may be for a succession of years, produces flowers of one sex 
only, may in another season form either bisexual blossoms, or 
flowers of both sexes on the same plant. We have seen cases 
of the first kind in the ash and in some of the maples ; of the 
second in walnuts, mulberries, and hops ; while in certain kinds 
of vines, and in some strawberries, the fact alluded to is notorious. 
Dr. Spruce Journ. Linn. Soc.” xi. 1871, p. 95) records cases 
of the same kind in palms growing about the Amazon, and in 
which the trees produce chiefly female flowers one year, and 
take a comparative rest in the following one by forming male 
flowers, whose formation does not so greatly tax the energies of 
the tree. Evidences of the same tendency are afforded by the 
circumstances that the seeds of unisexual plants produce seed- 
lings, now of one, now of another, sometimes of both sexes, in 
very unequal proportions. ' The seeds of a Papaw, Garica 
Papaya, which were collected from a female plant in South 
America, produced, when sown at Mentone, seedlings which 
developed male flowers, and afterwards bisexual flowers mixed 
with the males — a condition never observed by the person who 
furnished the seed, though his attention was specially called to 
it. It seems probable that the changed conditions of growth 
may have induced the alteration ; but, as we shall see presently, 
such an assumption must not be accepted without question, as 
other causes may produce like results. Cuttings, also, and 
buds taken from a plant of one sex, though they will in general 
perpetuate the characters of that sex, have been occasionally 
known to develop flowers of the opposite sex. 
Dr. Spruce has not, so far as we know, done more than make 
very brief reference to his theory, and has not. yet sought to 
