EXPLANATION OF THE FIGURES. 491 



Figs. 3, 3*, 4. Thuja orientalis. 



FIG. 



3. End of a pollen-tube, detached, x 250. 



3*. Some of the contents of the pollen-tube shown in fig. 3, X 500. 



4. End of a pollen-tube detached, x 250. 



Figs. 5, 6. Juniperus Siberica. 



5. Nucleus of the ovule with the lower portion of the integument of the 



ovule, in longitudinal section ; on June 5th of the first year, x 300. 



6. Detached embryo-sac at the end of May of the second year, which has be- 



come filled with cellular tissue for the second time. The membrane of 

 the embryo-sac is swollen with water, x 60. 



PLATE LXV. 



Fig. 1. Juniperus Sibirica. 



1. Apex of the embryo-sac filled with .endosperm, in longitudinal section ; 



three corpuscula are exposed ; on June 9th of the second year, X 300. 



Figs. 2 7. Juniperus communis. 



2. Corpuscula cut longitudinally, with a small portion of the endosperm and 



the pollen-tube ; on the 20th July, X 300. 



3. Three impregnated corpuscula, with the lower portion of the pollen-tube 



(longitudinal section of an endosperm on July 28th), x 300. 



4. Pro-embiyo consisting of three longitudinal rows of cells. 



5. Longitudinal section of an impregnated ovule (the integument is omitted 



in the drawing). The pointed line in the endosperm shows the 

 boundaries of the region in which the cells are loosened and partly dis- 

 solved. The development of the embryos of this specimen corresponds 

 almost with that of the one shown in fig. 7. (Beginning of August.) 

 X 30. 



6. Lower end of one of the isolated longitudinal rows of cells of a pro-embryo, 



with the mother-cell of the embryo still undivided, x 150. 



7. A similar specimen, with a more developed rudiment of the embryo. 



8. A similar specimen. 



Figs. 9 10*. Thuja orientalis. 



9. Upper end of the endosperm with the group of corpuscula and two pollen- 



tubes which have penetrated into the depression above it, in longitu- 

 dinal section ; on June 18th, x 250. 



10. A similar specimen with a single pollen-tube, which has sent prolongations 

 into the corpuscula; on June 28th, x 250. 



10*. The pollen-tube of the latter preparation detached. 



