Elementary Work in Botany. 



Fig. 18. A 

 germinating 

 squash seed, 

 showing a 

 "peg" which 

 holds the 

 lower half of 

 the st'ff coat 

 while the 

 growth of the 

 bent stem 

 (hypocotyl) 

 above it pries 

 open the seed 

 and liberates 

 thecotyledons. 



in the sack-like inner coat of the seed ? Your pine-nuts 



will come up in a similar manner, as 



shown in Fig. 9. When the shell is 



thrown off examine the sack within to 



determine whether the endosperm has 



been taken up. What absorbs the 



endosperm ? 



[Read and discuss in the class, .] 



Germination of Squash Seeds. 



Have you discovered how squash embryos 

 pry open their tough 

 coats ? Soon after the sprout has 

 gained a foothold in the soil, a little 

 knob grows on the side of the caulicle 

 so as to split more widely open the 

 point of the seed coat, as shown in Fig. 

 1 8. Then the hypocotyl between the 

 knob and the cotyledons, by growing, 

 pries the seed still wider open, as seen 

 at b in Fig. 19. Finally, by continued 

 growth, the cotyledons are pulled out 

 of the seed coat and upward to the sur- 

 face of the ground, where they expand, 

 and become pretty good leaves. Seeds 

 planted edgewise, which of course 

 could rarely happen in nature, cannot 

 thus free themselves of their seed coats, 



and it has been proved by a French botanist (M. Flahault) 



Fig. 19. a. A squash em- 

 bryo just appearing above 

 ground, the elastic coat grasp- 

 ing the "peg" which enabled 

 the growing hypocotyl to 

 pull the cotyledons out. b. 

 An embryo which, after 

 sprouting as shown in Fig. 

 18, was turned over. Then 

 the caulicle again bent down- 

 ward and grew a new "peg." 



