APRIL. 87 



material stored up inside the nut before its root and stem 

 are sufficiently matured to perform their full functions. 



Just as there are among birds whole families in which 

 the young are well advanced when hatched out of the egg, 

 and others in which they are in a very imperfectly formed 

 condition, so there are families of plants with very fully 

 developed embryos in their seeds, and others in which the 

 embryo is in a very rudimentary condition and ha.s a store 

 of nutritive material laid up alongside of or round it, and 

 which it must use up before it is ready to begin life on its 

 own account. 



In both cases the development of the young has no 

 direct relation to the ultimate development of the adult 

 form. Thus some of the most highly differentiated birds 

 hatch out their young in a very imperfect condition, 

 whilst those which are so very wide-awake as chickens 

 are not characterised by great intelligence in the adult 

 state. The seeds of plants belonging to the Cruciferse, an 

 order of plants with rather simple flowers, always have 

 the embryo in a well advanced condition, while the highly 

 developed family of orchids most wonderful, and in 

 respect of the flowers the most highly specialised of 

 flowering plants have their embryos in the most elemen- 

 tarv condition known. 



