THE ADVANCE OF SCIENCE 



117 



necting canals and threads (see fig. 33) is one of the most 

 startling facts discovered in connection with plant-struc- 

 ture, since it was held twenty years ago that a fundamental 

 distinction between animal and vegetable structure con- 

 sisted in the boxing-up or encasement of each vegetable 

 cell-unit in a case of cellulose, whereas animal cells were 

 not so imprisoned, but freely communicated with one 

 another. It perhaps is on this account the less sur- 



Attraction-sphere enclosing two centrosomes. 



Nucleus 



Plasmosome or 

 true nucleolus. 



Chromatin- 



network. 



Linin-network. hr^j 



Karyosome or 



net-knot. 



Plastids lying in the 

 cytoplasm. 



Vacuole. 



Lifeless bodies (meta- 

 plasm) suspended in 

 the cytoplasmic reticu- 

 luni. 



FIG. 34. 



Diagrammatic representation of the structures present in a typical cell 

 (after Wilson). Note the two centrosomes, sometimes single. 



prising that lately something like sense-organs have been 

 discovered on the roots, stems, and leaves of plants, which, 

 like the otocysts of some animals, appear to be really 

 ' statocytes,' and to exert a varying pressure according to 

 the relations of these parts of the plant to gravity. There 

 is apparently something resembling a perception of the 



