474 THE FERTILISATION OF FLOWERS. [PART III. 
on the same stock, on the contrary, are all much of the same size, 
as my explanation requires, but the hermaphrodite flowers enlarge 
in passing from the first (male) to the second (female) stage. The 
certainty of cross-fertilisation, which is also necessary for my theory, 
is in a high degree a character of Thymus; for the honey is ex- 
ceedingly abundant and has an aromatic taste, the base of the 
ovary by which the honey is secreted (n, 5,6) is many times as 
large as the ovary itself, the aggregation of the flowers and their 
strong scent reveal them to insects and permit insects to visit 
many with. little loss of time, and from the reproductive organs 
protruding beyond the corolla many flowers may be fertilised at 
once as the insect clambers over the inflorescence. The tube is 
smooth at the base where the honey lies, and lined with hairs above 
to exclude rain; it is only a few millimetres long (25 to 4 mm. in 
T. Serpyllum), so that the honey is accessible to a great variety of 
insects. Self-fertilisation was impossible in all the flowers that I 
have examined, for the style, which in the first stage is short and 
overtopped by the anthers (Fig. 161, 1, 5), elongates and grows 
out beyond the anthers before its two divisions with the stigmatic 
papille at their tips spread apart." 
Darwin found the female form very much more productive than 
the hermaphrodite, both in 7. Serpyllum and T. culgaris. 
While Darwin in England, Hildebrand in the Rhine Provinces, 
Ascherson, according to his /ora, in Brandenburg, and I in 
Westphalia and Thuringia, have only observed the two forms, female 
and hermaphrodite, of this plant, Delpino, near Florence, has 
found the plant trimorphic: he states that it consists there of 
hermaphrodites with both stamens and pistil equally developed ; 
of others with greatly developed stamens and the pistil in every 
stage of abortion, or even absent; and finally, others with greatly 
developed pistil and more or less aborted stamens (No. 173, p. 7). 
In England also there seems to be a passage towards purely male 
flowers, for, according to Dr. Ogle (No. 632, p. 54), in many of the 
liermaphrodite flowers the stigma never reaches maturity. With- 
out accurate information concerning the size of the flowers, the 
time of their development, the frequency of insect-visits, and the 
relative distribution of the two forms, all attempts at explanation 
must be unsatisfactory. 
Visitors: A. Hymenoptera—(a) Apidw: (1) Apis mellifica, L. §,s. and 
c.p.,ab. ; (2) Bombus pratorum, L. 2, do. ; (3) Saropoda bimaculata, Pz. 2 ¢> 
' Compare my account of Nepeta Glechoma, yp. 484, and Darwin’s account of 
Thymus, No, 167, p. 800. 
