THE ENDOSPERM 



243 



In a few plants, well-developed and aggressive haustoria of all 

 three kinds — micropylar, chalazal, and secondary — occur together 

 and form a very efficient absorptive system. An interesting case of 



B 



D 



Fig. 136. Development of the endosperm in Alonsoa. Small globules lying around 

 nuclei are starch grains. A, mature embryo sac. B, first division of endosperm 

 mother cell. C, transverse division in micropylar chamber resulting in a three- 

 celled stage. D, more advanced stage, showing four-celled micropylar haustorium 

 (only two cells are seen in section), two-celled chalazal haustorium (one of the 

 cells is lying over the other), and central cells destined to give rise to endosperm 

 proper. (After Krishna Iyengar, 1937.) 



this kind has been described by Rosen (1940) in Globularia vulgaris, 

 belonging to the allied family Globulariaceae. The micropylar 

 haustorium consists of two to four separate cells but they soon 

 unite to form a single entity. This composite structure often grows 



