STRUCTURAL ELEMENTS OF THE CYTOPLASM. l8l 



my report, corroborate my findings in a general way, but offer 

 some very remarkable differences in detail. My work with these 

 methods has shown that they will impregnate practically every- 

 thing in a plant cell except chromosomes (and probably central 

 bodies when they occur). The classes of materials thus demon- 

 strated may be tabulated as follows: 



1. Osmiophilic platelets, 



2. Plastidome, 



3. Pseudochondriome, 



4. Vacuome, 



5. Nucleus not including the nucleolus as a rule, 



6. Intra-nucleolar bodies, 



7. Spindle fibers, cytoplasmic network and cell plate, 



8. Intra-vacuolar masses. 



The outcome of any particular trial can not in general be fore- 

 told, and these osmic methods can only be interpreted with 

 accuracy after extensive experience and not always then. In 

 spite of the obvious disadvantages arising from their excessive 

 lack of specificity, these methods nevertheless yield results un- 

 equalled by any other technique, and can not fail to be of extra- 

 ordinary interest and value to anyone engaged in the study of 

 plant cells. 



The methods here outlined together with others will be given 

 in another paper the detailed consideration which space does 

 not now permit. 



RESULTS ON ROOT-TIPS. 



The Osmiophilic Platelets. Following osmic impregnation, the 

 most generally demonstrated components of the cell are the 

 osmiophilic platelets. I have given them this name merely as a 

 convenient descriptive term, pending the final adjudication of 

 their status. They have the shape of plates or discs, the 

 periphery of which is intensely blackened by osmic acid (Figs, i 

 and 8). The central part may be quite clear or may be slightly 

 blackened or browned in varying degree. Just what the exact 

 morphology of these bodies may be is not known, but the 

 impression one gets is that of a plaque with a peripheral rim of 

 specifically different composition. When seen in face view, the 



