MYRTACE.E 527 



thick and woody testa both during and after germination it 

 would be protected from the depredations of animals. Coty- 

 ledons are absent or very minute. This being the case it 

 follows that the seedling must behave differently from those 

 having cotyledons which are also generally if not always 

 petiolate when they are subterranean or remain in the testa 

 in germination, as in Eugenia bracteata and others mentioned 

 above. The petioles in these cases allow the whole of the 

 embryo to escape from the testa, with exception of the fleshy 

 laminse of the cotyledons. On the contrary the fleshy 

 hypocotyl of Lecythis Zabucajo is held fast while the plumule 

 splits the testa and pushes its way out at one end of the 

 seed and the radicle at the other. The allied Bertholletia 

 excelsa (fig. 350) behaves in the same way, as well as Barring- 

 tonia speciosa. 



That there is good ground for considering this fleshy un- 

 divided embryo as homologous with the hypocotyl may be 

 inferred from species belonging to other genera. For instance 

 in Couroupita the radicle (so called) is long, clavate and 

 curved round the outside of the cotyledons ; in Couratari it is 

 very large and cylindrical ; in Planchonia it is very long, 

 clavate and spirally convolute, while the cotyledons are short ; 

 but in Careya, Barringtonia, Lecythis and Bertholletia the 

 embryo is quite undivided, with a bud at one end and the 

 radicle proper at the other. 



It is usual for some of the primary leaves to be reduced 

 to colourless or brown scales when the cotyledons are subter- 

 ranean. The first two pairs of Eugenia bracteata are in this 

 condition. A great number of the primary leaves of Berthol- 

 letia excelsa are very small and completely cover the lower 

 part of the stem owing to the non-development of the inter- 

 nodes. They gradually change from sheathing organs to 

 perfect leaves, of gradually increasing length. The first eight 

 are colourless, the next five are oblong, followed by one or 

 more lanceolate ones, while the fifteenth and sixteenth are 

 oblong-obovate, but very moderate in size. Only three or 

 four of the first leaves of Lecythis Zabucajo are scale-like. 

 In all three species the colourless leaves would act as a pro- 

 tection to the plumule while pushing its way through the soil, 



