102 ATLAS OF BIOLOGY. 



FIG. X. Developing pollen-grains, from the anther of a young Buttercup. Teased. 

 F. 3. 



FIG. XI. Surface view of a thick longitudinal section, through the stigrua of an open 

 BiMercup. 



The central shaded portion * represents the central cavity of the style. Alcohol and 

 weak glycerine. D. 3. 



FIG. XII. Slightly diagrammatic longitudinal section of the entire carpel of an open 

 Buttercup, at the period of fertilization. 



This figure represents the facts, as pieced together from observations made upon a 

 number of sections, obtained as for Fig. VII. 



* Indicates a single well-differentiated layer of cells, surrounding the central canal of 

 the style. 



FIG. XIII. Transverse section of the carpel of an unopened flower of Lilium, to show 

 the general relations of the ovules, etc. 



The parts indicated in black represent the passage open to the pollen tube, when once 

 it has entered the central canal of the style. A. 2. 



FIG. XIV. An ovule from the same, more highly magnified. D. 2. 



FIG. XV. A similar section from the carpel of a much younger flower. D. 3. 



FIG. XVI. Three embryo sacs from the same carpel as Fig. XIII., to show the 

 changes undergone prior to fertilization. D. 2. 



As numbered in order i. to iii. they represent successive stages in the development of 

 an individual. Figs. XIV. and XV. present still earlier phases in the same development. 



The above sections (Figs. XIII. to XVI.) were prepared from fresh material, transferred 

 as cut into a half-and-half solution of methylated spirit and glycerine, and kept exposed in 

 a warm room until the spirit had evaporated. 



FIG. XVII. An ovule, teased up from the fruit of the Shepherd's Purse. A. 3. 



FIG. XVIII. The embryo drawn in Fig. XVII. i. liberated under gentle pressure. 

 D. 4. 



FIGS. XIX. and XX. Two embryos, teased from younger fruits of the same plant. 

 D. 4. 



The three embryos above figured represent successive stages in development, and 

 only such are here drawn as can be readily seen with ease by teasing up the fruits with 

 needles. 



For further details see Hanstein's figures, reproduced in all the text-books. 



