123 



One reason why these records are incomplete is that, during a generation, 

 seedlings have disappeared at various stages through accident, climatic changes, attacks 

 by insects and animals, and the various happenings of a nursery. In one case, -a 

 larger number disappeared, one knows not where; they were probably distributed 

 with others for some public purpose. In some cases seeds produced weakly plants; 

 in others, the quantity was so very small as not to permit a second sowing. But the 

 work has been begun, and will go on. 



While there have been very many advantages in conducting these seedling 

 researches in the nursery of a public institution, I have many a time sighed for the 

 greater security and privacy of a private garden. 



6. NOTES ON THE EMBRYO. 



(Including notes on Cotyledons, &c, which have been dealt with under separate 



headings.) 



" We must first of all distinguish between seed-leaves and shoot-leaves, with regard to their point 

 of origin from the stem. The former only occurs in the embryo, the latter in all those structures comprised 

 under the term " shoot." The embryo which has developed from the fertilized egg-cell in the embryo-sac 

 presents in many instances a tissue-body in which as yet no trace can be recognised of a differentiation 

 into stem and leaf, or rather the embryo, when it leaves the fruit-capsule, is like a stem in which all 

 indication of leaves is absent " 



" In the majority of instances, however, a distinct differentiation can be recognised in the embryo 

 hidden in the seed, and one or two leaves may be seen issuing from the tissue-mass which forms the axis 

 of the embryo. These are the seed-leaves or cotyledons. 



: ' The short axis or stem-portion from which the seed-leaves originate, and which looks like the 

 pedestal of the cotyledons, is called the hypocotyl. 



" At one end of the hypocotyl a tissue-mass is developed, termed the radicle, at the opposite end a 

 tissue-mass named the plumule. 



" The plumule is situated above the place where the cotyledon or pair of cotyledons issued from the 

 hypocotyl. It is the rudiment of a new portion of the stem, which is situated above the cotyledons, and 

 is called the epicotyl. 



" The epicotyl thus originates from the apex of the hypocotyl, and the boundary between these 

 two portions of the stem is the place of origin of the cotyledon, or pair of cotyledons." (Kerner and 

 Oliver, i, 596.) 



