370 METHODS IN PLANT HISTOLOGY 



Zea mays, especially the sweet corn, is a good type to illustrate the 

 peculiar embryo of the grasses. Directions have been given on page 

 352. 



In many forms good preparations of late stages may be secured by 

 soaking the seeds in water until the embryo bursts the seed coat. 

 Young seedlings furnish valuable material for a study of vascular 

 anatomy. 



Parthenogenesis. — Many embryos are developed without fertiliza- 

 tion. Taraxacum, the common dandelion, is an omnipresent example. 

 Other widely distributed illustrations are Hieracium and practically 

 all species of the Eualchemilla section of the genus Alchemilla. Par- 

 thenogenetic forms show various irregularities in the mitoses leading 

 up to the formation of the egg. 



