DEVELOPMENT. 107 



seeds were buried in the first digging and brought to the surface in the 

 second. In midsummer ^V. zanzibariensis seeds will germinate quickly 

 after maturing, and the bags of seed must be gathered as soon as the fruit 

 bursts ; but in the summer of 1900 numerous seedlings of this plant 

 sprang up in the pond of the Botanic Garden (University of Pennsylvania) 

 and blossomed before frost ; they must have come from seed ripened in 

 the previous autumn. Mr. Waters (1886) gives an interesting account of 

 the germination of N. odorata. Seeds gathered in the fall of 1883 were 

 sown at once in an aquarium kept in a living room with north light. In 

 March, 1884, many were germinating. In June, 1885, the vessel was placed 

 where it received direct skylight with sun for an hour at noon ; a half 

 dozen new plants appeared in August. In the fall they were returned to 

 the living room, and about Christmas another seed had germinated. 

 From February to April, 1 886, four others sprouted ; these had therefore 

 lain dormant for about two and a half years, although they were constantly 

 in conditions which would permit germination. 



The general features of a seedling Nymphaea were noted by Titt- 

 mann in 1821. Treviranus, Caspary, Klebs, Goebel.and others have since 

 remarked upon or figured such seedlings. The first visible evidence of 

 life in the seed is the loosening of an operculum at the apex (Fig. 49, 8, o). 

 This is a conical body bearing the micropyle and hilum ; its edge is ragged 

 by reason of the sinuous margins of the cells of the testa. The operculum 

 is pushed aside by the protruding embryo and its wrappings, and lies on 

 these at one side near the edge of the opening from which it was torn. 

 The seed coat is also rent with short longitudinal fissures, dividing the lip 

 of the aperture first formed into numerous acute teeth (Fig. 49, 8). As 

 the embryo emerges it is covered by a white sheath produced by the 

 swelling and straightening out of the overlying " rumpled up " portion of 

 the inner seed coat ; this protects it from the sharp and ragged edges of 

 the testa. The cotyledons remain permanently within the seed and show 

 no changes in the inner parts except in the emptying of the cells. It is by 

 the elongation of the bases of the cotyledons into a kind of petioles that 

 the radicle and plumule are passively carried out of the seed. These coty- 

 ledonary petioles also curve geotropically downward until the caulicle is in 

 a vertical position, and then they cease to grow (Fig. 49, 3, 4). 



Through all this time the plumule and radicle have remained dormant, 

 but now both start into activity, the former very rapidly. The hypocotyl 

 does not elongate at all. The epicotyl and first leaf shoot upward as a 

 slender subulate body (Fig. 49, 3, 4). The elongation of the epicotyl 



