214 UniversHij of California Puhlications in Botanii r^'*^"-" 



especially in llie case of sections involving- cliloroi)liyllous tissue, to 

 stain the i)rot()|)lasmie matrix of tlic cell and follow with Sudan III. 

 It appears that a heavy staining willi Orange G. followed hy Sudan 

 III may he a useful eonihination in this connection. Of a number of 

 stains ordinai'ily employed for the diiferentiation of the elements of 

 woody tissue one at least gave some indication of being of interest. 

 Sections were placed in Delafield's haeniatoxylin for twelve hours, 

 partially destained and placed over night in Sudan III. In the result- 

 ing preparation the rubber inclusions wei-e stained scarlet by Sudan 

 III while in llie center of each was a single spot of dark purple indi- 

 cating, apparently, that each i-ubbei- globule contains a |ttotoplasmie 

 "nucleus'' around which it is built up. Results of this sort indicate 

 a field for further investigation. 



It occurred to us, also, that vulcanization of the rubber in situ 

 might be possible, and thus giving specific differentiation under the 

 microscope to rubber inclusions in the cell. After suitable dehydra- 

 tion, sections were placed in the cold in sulfur chloride (in carbon 

 tetraeholoride) or were allowed to stand in the fumes of such a solu- 

 tion. The results of a number of preliminary experiments indicated 

 that vulcanization of the rubber inclusions in the cells w^as possible. 



The following outline of the process of making preparations of rub- 

 ber-containing tissue described in some detail above may be of assist- 

 ance to those who may desire to make histological examinations for a 

 similar purpose. Attention must be called to tlie fact that nothing 

 original is claimed for this process, nor will it necessarily prove suc- 

 cessful in all its details for other species. 



It is assumed that a woody plant is under investigation and that 

 sections have been cut from a sample of mature tissue. 



(1) Sections from water to 95 per cent aleoliol : .") minutes. 



(2) Boiling acetone; 15 to oO minutes. 



(3) Sudan III; 18 hours. 



(4) AVash off excess of stain in 50 i)er cent alcohol ; as rapidly as 

 ])Ossible. 



(5) [Mount in pure glycerine. 



A preparation made in this manner from material cut from a rela- 

 tively higii percentage plant of Clirysotlunnnns nauseosus will show 

 cell inclusions of rubber stained a brilliant scarlet. At a magnification 

 of 150 diameters the parenchymatous elements of the cortex and es- 

 pecially the broad wedge-shaped cortical extensions of the i)rimary 



