28 THE VOYAGE OF H.M.S. CHALLENGER. 



ment of this interesting plant under cultivation, the results of which were published, 1 and 

 are here repeated in a condensed form. Seeds were sent to the Gottingen Botanic 

 Garden from the Argentine province of Entre Rios, and both kinds were equally fertile, 

 though the young plants from the seeds of underground pods grew more vigorously from 

 the first than the others did. Nevertheless, by the time the plants reached the flowering 

 stage this difference had disappeared. The underground pods contain one, 2 or, at most, 

 two relatively large seeds ; while in the normal aerial pods, the seeds are numerous and 

 small. Probably the greater vigour of the plants from the seeds ripened underground 

 was due to the greater amount of nourishment they abstracted from the mother plant. 

 Briefly, a plant of Cardamine chenopodifolia maybe described as similar to a plant of the 

 common Carclamine pratcnsis, but it has entire leaves ; and from the axils of the rosette 

 of leaves at the base of the stem spring the peduncles of the flowers which ripen their 

 seeds underground. These bear each one terminal flower, produced at the same time as 

 the ordinary erect inflorescence. Almost as soon as they are visible, they begin to curve 

 downward, and before the flowering period they have thrust themselves into the ground 

 to the average depth of four-fifths of an inch. The flowers are so small as to be almost 

 imperceptible to the naked eye, for they only attain a length of a millimetre (about one 

 twenty-fifth of an inch), with a diameter of a thirty-second part of an inch, looking 

 more like the blunt end of a peduncle, especially as they remain closed. But the normal 

 flowers are also very small, having petals only about one-sixth of an inch long. Whereas, 

 however, these exhibit the ordinary Cruciferous structure, the underground ones consist of 

 only four green sepals, with four stamens apparently opposite to them, and a pale pistil. 

 The latter contains one pendulous anatropal ovule in each cell. Exceptionally a peduncle 

 is unable to penetrate the ground, and then the pod lies flat on the ground, and is green 

 instead of being blanched. The process of fertilisation of the underground flowers, which 

 was investigated by Dr Drude, proved far more remarkable than the abnormal structure 

 of the flowers. The accuracy of the observations Dr Grisebach was able to confirm by an 

 examination of Dr Drude's microscopic preparations. It appears that each cell of the 

 anther contains only about twelve pollen grains of globular shape, with tetrahedrously- 

 arranged pores and a thin warty extine. The anther cells do not dehisce, but the pollen 

 tubes grow out and pierce the wall, and at once enter the contiguous stigma. Iu the 

 ovary, the pollen tubes could be traced into the micropyle of the ovule, which was already 

 impregnated, though the pollen tubes remained visible. A comparison of the individual 

 pollen grains of the underground flowers with pollen grains of the aerial flowers revealed 



1 Der Dimorphisiuus der Fortpflanzungsorgane von Cardamine chenopodifolia, Fers. — Nachrichten von der 

 KUniglicken Gesellschaft der Wissenschaften und der G. A. Universitat zu Gottingen, Juni 1878, p. 332 ; 

 reprinted in the Botanisehe Zeituwj, 1878, pp. 723 and 794. 



2 The ovary of the flowers that bury themselves appears to be invariably two-celled, with one ovule in each 

 cell ; and Grisebach states that, contrary to St Hilaire's account, both ovules were fertilised in the cultivated 

 plant, but in all the wild specimens we examined, except one, only one seed was developed. — W. B. H. 



