THE ANGIOSPERMAE 



1365 



tion of a periplasmodium, the other is called by Goebel the " secretion 

 type ". In both cases the cells of the inner parietal layers may take part, as 



well as the tapetum proper. „ r u 



The periplasmodium is formed in three stages. The cell walls ot the 

 tapetum dissolve (Fig. 1268) and the protoplasmic contents of the cells 







Fig 1268.— Commelina coelestis. Formation of a plasmodial tapetum. Only one 

 or two cell walls remain intact and the nuclei have become irregular m 

 shape. {Fiom Tischler, ''jf.f. n'iss. Bot." 55.) 



separate from one another. They then grow out in strands of varying form, 

 pass between the pollen grains, and only unite together when they reach 

 the middle of the loculus. The amoeboid mass thus formed increases m 

 bulk until the spaces of the loculus are almost or quite filled. Lavatera is 

 exceptional in that the plasmodium concentrates around the grains and 

 leave? large spaces of the loculus unfilled. 



