386 MONTGOMERY. [Vol. XV. 



deeply stained, and change into globular colloid-loolcing masses 

 witli a central more deeply stained spot. I propose to call these 

 bodies paranucleoli, because of their origin they may always be 

 found in the micropylar nucleus and occasionally also in the 

 antipodal nucleus." When these nuclei begin to conjugate, 

 the large nucleoli of both fuse to form the single nucleolus of 

 the primary endosperm nucleus ; at the same time a new struc- 

 ture makes its appearance, in close contact with the nuclear 

 membrane of the primary endosperm nucleus : "This body . . . 

 corresponds, I believe, to the nucleolar membrane of the 

 antipodal nucleus" ; it is at first granular, later homogeneous. 

 Still other, smaller spherical bodies later appear in the nucleus, 

 which may have some connection with the paranucleoli. Finer 

 structure of the nucleolus : in the nucleolar membrane " a 

 number of very minute dark radially placed pores or striae can 

 be observed, and . . . these striae are continued into very 

 delicate cilia-like fibrils radiating out from the nucleolar mem- 

 brane into the nuclear hyaloplasm. . . . The nucleolus is 

 differentiated into an outer zone and an inner zone. The outer 

 zone is less deeply stained, and on careful examination is found 

 to be made up of a circle of peripheral endonucleoli, which are 

 slightly elongated radially. The inner zone of the nucleolus 

 is very darkly stained, and shows a number of large and irregu- 

 larly disposed endonucleoli." The structure of the nucleolus 

 may be somewhat different in other stages of its development, 

 thus it may be composed of "(i) A thin unstained nucleolar 

 membrane ; (2) a great number of peripheral endonucleoli ; (3) 

 a deeply stained, apparently structureless, layer ; (4) a corona 

 of minute, slightly elongated, endonucleoli surrounding (5) a 

 large central endonucleolus. ... In a resting cell, . . . the 

 center of the nucleolus is occupied by a large endonucleolus, 

 which sends out minute fibrils through the nucleolar sub- 

 stance. ... I believe the endonucleolar fibrils probably to pass 

 through the finer pores in the nuclear membrane"; and Mann 

 conjectures that "the endonucleolar filaments constitute the 

 linin element of the chromosomes." Functions of the nucle- 

 olus: it is "concerned in the assimilation of food-material." 

 He holds "the nuclear chromatin to be less highly elaborated 



