SYMBIOLOGY THE BIOLOGICAL RELATIONSHIPS OF ORGANISMS 131 



in diameter. The normal form of the sphaerocytes, as the name would 

 indicate, is that of a perfect sphere, although some are more or less irregular 

 in outline and some show marked ameboid movement. Actively motile 

 sphaerocytes are comparatively numerous in the green tomato and also 

 in the green grape. The smaller and probably the younger sphaerocytes 

 of the fruits thus far examined have the following characteristics in 

 common: 



i. They are spherical in form excepting the motile forms referred to. 



FIGS. 45-48b x 450. 



PIG. 45. Different forms of sphaerocytes from the mucilaginous tissue of tomato 

 seeds. A, a fully matured sphaerocyte cell (Gliding cell); a, nucleus with nucleolus; 

 b, reddish brown coloring granules; c, intra-cellular sphaerocytes; d, chlorophyll gran- 

 ules. B, sphaerocyte nearly mature, showing several endo-sphaerocytes. C, sphaero- 

 cytes in various stages of development. D, amebo-sphaerocytes of the ripe tomato. 

 E, a mature nucleo-sphaerocyte; a, nucleus with nucleolus; b, reddish brown coloring 

 particles; c, vacuoles; d, granular cell-plasm. 



2. The plasmic contents are rather delicately granular but there is 

 no evidence of streaming plasmic motion. The plasmic granula often show 

 slight active and also Brownian motion. 



3. There is no outer limiting membrane or cell wall, at least none is 

 demonstrable by the usual staining methods. 



4. Vacuoles are generally present and are very variable in size. In 

 some sphaerocytes a single vacuole may occupy the greater portion of the 

 cell, leaving a mere meniscoid outer rim of granular plasm. More gener- 



