PARTHENOGENESIS 6i 



Kerner has recently again called the attention of botanists to Parthenogenesis, 

 by seeking to prove that it appears beyond doubt in Mercurialis annua. On account 

 of the great importance of this subject, I give Kerner's description ('Nat. Hist. PI.,' 

 Eng. Ed. I, II, pp. 465, 466) verbatim :—' At various times,' he says, 'female plants 

 have been reared quite alone in pots, and it has appeared that these have developed 

 seeds which, though fewer in number, are just as capable of germination as those pro- 

 duced by plants growing in the open country in the company of male stocks. This 

 result was doubted on all sides, and efforts were made to show that it was due to 

 the uncertainty of culture experiments. It was maintained that pollen-dust might 

 be carried from afar by the wind into the rooms made use of for the experiments, 

 and what seemed even more important, attention was called to the fact that some 

 plants with many female flowers may also bear a few male flowers. These criticisms 

 stimulated new experiments, in which suitable care was taken to avoid all possible 

 sources of error. For the new experiments those districts appeared specially favour- 

 able where for many miles round no dog's mercury was to be found growing wild, 

 and where therefore the possibility of the introduction of pollen from the surrounding 

 district was altogether excluded, as for instance some point in the middle Tyrol, 

 where both the annual and the perennial dog's mercury are altogether absent. In 

 such a district in the high-lying Tyrolean Gschnitzthal, I repeated the experiments 

 that had been made in 1833 by Ramisch, in Prague, with so much perseverance, 

 and, in my work, all those errors which had been attributed to the experiments 

 of Ramisch, were avoided. In particular, all plants on which buds of male flowers 

 appeared were at once destroyed, and careful attention was given to ascertain whether 

 some individual male or hermaphrodite flower might not possibly be concealed on 

 one or other of the female plants. At the time when the stigmas of the dog's 

 mercury were ready for pollination there were quite certainly for miles round 

 no wild pollen- cells of the plant, and fertilization by such pollen was therefore out 

 of the question. But, notwithstanding this, the carpels soon became swollen, 

 embryo-containing seeds developed from the ovules, and when these seeds were 

 sown vigorous young plants of dog's mercury grew up.' 



Perhaps Antennaria alpina Gaertner (Gnaphalium alpinum Z.) is also partheno- 

 genetic in the arctic regions, since, according to Vahl, Lange, and Warming, male 

 flowers of this dioecious plant are there unknown, although it fruits in numerous 

 localities. On the other hand, Hartman (Handbok i Skand. Flora, p. 7) describes 

 male plants from specimens which were found in 1847 by Laestadius (Loew, 

 'Blutenbiol. Floristik,' p. in). 



Kerner ('Nat. Hist. PI.,' Eng. Ed. i, II, p. 465), incited to observation by these 

 facts, has cultivated to the flowering-stage plants of Gnaphalium alpinum from the 

 Dovrefjeld in Norway, using every possible precautionary measure. All the flowers 

 developed ovules, but no poUen, so that pollination of the stigmas was quite impossible. 

 Yet some of the ovules became fruits with well-formed seeds, which germinated into 

 young plants when sown in sandy humus. These young plants agreed in every 

 respect with the parent stock and soon flowered, but, as before, their flowers only 

 bore carpels. From these results Kerner concludes that there can be no doubt 

 that G. alpinum multiplies by parthenogenesis in its remote northern habitat, 

 and that reproduction is not prevented by the failure of pollen-producing plants. 



