SPERMATOPHYTES— GYMNOSPERMS 



343 



embryo stages, like those shown in Figure 119, are Hkely to show 

 plasmolysis; but, by reducing the chromic acid to 0.5 c.c. and increas- 

 ing the acetic acid to 3 c.c, and fixing for 48 hours, there is less danger. 



Fig. 120. — Pinus laricio: photomicrograph showing the formation of the ventral canal cell; 

 iLsually this cell is not so large in proportion to the egg; fixed in Flemming's weaker solution and 

 stained in safranin, gentian violet, orange; the preparation was made in 1897, the photomicrograph 

 in 1915; Cramer contrast plate; 4-mm. objective; ocular X4; Abbe condenser; yellowish-green filter 

 and also a strong filter used in outdoor photography; camera bellows, 75 cm.; arc light; exposure, 7 

 minutes. Negative by Miss Ethel Thomas. X587. 



Stages, like those shown in Figure 1195-D, without any shrinking, 

 were secured by Miss Ethel Thomas by using hot alcoholic corrosive 

 sublimate-acetic acid with formalin (4 g. corrosive sublimate, 5 c.c. 



