418 
Hill. — Shtdies in Seed Germination. 
Gressner’s own view (1. c., p. 837), which is that Cyclamen has two cotyledons. 
The second cotyledon, according to him, is present only as a rudiment in 
the mature embryo, but develops later to form the second green leaf of the 
plant. Hildebrand’s 1 views are based on more sound observation, for he 
speaks of the ‘second leaf’ as a small protuberance and mentions that its 
development can be artificially hastened by the removal of the blade of the 
‘first’ leaf (i. e. the cotyledon). But both Gressner and Hildebrand confuse 
the issue by referring to the ‘ second ’ leaf, for under normal conditions the 
embryonic rudiment or protuberance very rarely develops, and the ‘ second ’ 
leaf of the young seedling Cyclamen is actually the first plumular leaf and 
is similar both morphologically and physiologically to the mature leaves of 
the plant. 
Hildebrand, like Gressner, does not distinguish clearly between the 
true second cotyledon and the first plumular leaf, and judging from his con- 
cluding paragraph (1. c., pp. 9 6, 97) he did not consider the question of any 
particular interest in the biology of the seedling of Cyclamen persicum. 
The embryo of Cyclamen persicum is also described and figured by 
Schmid. 2 He points out that there are two cotyledons, one of which is 
represented only by a rudiment, but he does not follow the germination or 
study the fate of the rudimentary second cotyledon. 
Coulter and Chamberlain, 3 in their discussion of dicotyledonous 
embryos with a single cotyledon, are thus incorrect in stating that Schmid 
‘ found embryos in ripe seeds of Cyclamen persicum with no trace of a second 
cotyledon ’. These authors point out that in certain dicotyledonous forms 
there may be early abortion which may even approach suppression of one 
of the cotyledons ; and that in consequence of this the single functional 
cotyledon may appear terminal and the stem-tip lateral. ‘To call such 
cases pseudomonocotyledons ”, however, is not consistent with the real 
nature of the monocotyledonous embryo.’ 4 
No definite pronunciation is made by Goebel 5 as to whether cyclamen 
possesses two cotyledons or only a single one. He speaks of the seedling 
having only a single leaf, which is followed in due course by other primary 
leaves of similar form, and allows it rather to be assumed that there is only 
a single cotyledon in this genus. 
Goebel 6 carried out an extensive series of experiments on Cyclamen 
1 Hildebrand, F. : Die Gattung Cyclamen. Jena, 1898, p. 95. 
‘ 2 Schmid, B. : Bot. Zeit., 1902, p. 217, PL IX, Figs. 45-7. The lettering given in the 
explanation of Fig. 47, which shows the second cotyledon rudiment, does not agree with that on 
the plate. 
3 Coulter and Chamberlain : Morphology of Angiosperms, 1904, p. 206. 
4 Ibid., p. 207. 
5 Goebel : Einleitung in die experimentelle Morphologie der Pflanzen, 1908, p. 203. 
6 Goebel; Ueber Regeneration im Pflanzenreich. Biolog. Centralbl., xxii, 1902, pp. 435-8 and 
pp. 481-7, with numerous text-figures. This work is shortly summarized in his Einleitung in die 
experimentelle Morphologie der Pflanzen, 1908, pp. 203-6. 
