Flowers on a completely self-impotent plant of Passiflora alata fertilised with pollen from its own self-impotent seedlings were quite fertile.  Mr. Scott, and afterwards Mr. Munro, found that some species of Oncidium and of Maxillaria cultivated in a hothouse in Edinburgh were quite sterile with their own pollen; and Fritz Muller found this to be the case with a large number of Orchidaceous genera growing in their native home of South Brazil. (9/2.  ‘Botanische Zeitung’ 1868 page 114.) He also discovered that the pollen-masses of some orchids acted on their own stigmas like a poison; and it appears that Gartner formerly observed indications of this extraordinary fact in the case of some other plants.

Fritz Muller also states that a species of Bignonia and Tabernaemontana echinata are both sterile with their own pollen in their native country of Brazil. (9/3.  Ibid 1868 page 626 and 1870 page 274.) Several Amaryllidaceous and Liliaceous plants are in the same predicament.  Hildebrand observed with care Corydalis cava, and found it completely self-sterile (9/4.  ‘Report of the International Horticultural Congress’ 1866.); but according to Caspary a few self-fertilised seeds are occasionally produced:  Corydalis halleri is only slightly self-sterile, and C. intermedia not at all so. (9/5.  ‘Botanische Zeitung’ June 27, 1873.) In another Fumariaceous genus, Hypecoum, Hildebrand observed that H. grandiflorum was highly self-sterile, whilst H. procumbens was fairly self-fertile. (9/6.  ‘Jahrb. fur wiss.  Botanik’ B. 7 page 464.) Thunbergia alata kept by me in a warm greenhouse was self-sterile early in the season, but at a later period produced many spontaneously self-fertilised fruits.  So it was with Papaver vagum:  another species, P. alpinum, was found by Professor H. Hoffmann to be quite self-sterile excepting on one occasion (9/7.  ‘Zur Speciesfrage’ 1875 page 47.); whilst P. somniferum has been with me always completely self-sterile.

Eschscholtzia californica.

This species deserves a fuller consideration.  A plant cultivated by Fritz Muller in South Brazil happened to flower a month before any of the others, and it did not produce a single capsule.  This led him to make further observations during the next six generations, and he found that all his plants were completely sterile, unless they were crossed by insects or were artificially fertilised with pollen from a distinct plant, in which case they were completely fertile. (9/8.  ’Botanische Zeitung’ 1868 page 115 and 1869 page 223.) I was much surprised at this fact, as I had found that English plants, when covered by a net, set a considerable number of capsules; and that these contained seeds by weight, compared with those on plants intercrossed by the bees, as 71 to 100.  Professor Hildebrand, however, found this species much more self-sterile in Germany than it was with me in England, for the capsules produced by self-fertilised flowers, compared with those from