LABORATORY PRACTICE 



Examine a seedling which has been carefully re- 

 moved from the earth and notice that : 



2. The cotyledon remains within the seed-coats closely 



applied to the endosperm, which becomes semi-fluid 

 and milky, is gradually absorbed by the cotyledon 

 (acting as a sort of sucker) and transferred to the 

 growing parts, which are : 



3. The primary root or roots, arising from the tip or sides 



of the caulicle, which lengthens very little, and 



4. The elongated plumule, which consists of nodes, each 



bearing a single grass-like leaf, and short internodes. 



5. Notice that roots are also given off just above the coty- 



ledon and from the nodes of the plumule. These 

 are adventitious roots. The difference between ad- 

 ventitious and primary roots is, that the primary roots 

 grow from the caulicle, i.e. originate below the cotyle- 

 dons, while adventitious roots originate above the coty- 

 ledons. 



6. Sketch a seedling of the Indian Corn, showing these 



points. 



VIII. Examine several pots of Onion Seedlings of various 

 ages and notice : 



1. The green loops just appearing above the ground and 



becoming larger until they pull the seed-coats and the 

 endosperm out of the ground. 



The examination of seedlings which have been 

 carefully removed from the soil, shows that : 



2. The green loop is in each case the single cotyledon 



which, by its elongation, has pushed the short cau- 

 licle out from the seed-coats and has finally pulled 

 the seed-coats and endosperm from the ground, while 



