PLATE XII. 



FIG. 119. The lower portion of a pollen-tube which has penetrated about two- 

 thirds the length of the nucellar cap. X 472. Pinus Strobus. June 

 14, 1898. 



1 20. The lower portion of a pollen-tube which is just pushing between 

 the neck-cells of the archegonium. f, pit in apex of tube. X 47 2 - 

 Pinus Strobus. June 20, 1898. 



121. A vertical section of a young cone; the ovuliferous scales have not as 

 vet been organized. X 57- Pinus austriaca. March 14, 1898. 



122. Section of an ovuliferous scale showing the first indication of an 

 ovule, m. ovule ; o.s, ovuliferous scale ; b, bract. X 150* Pinus 

 Strobus. May 3 1, 1898. 



123. A vertical section of an ovule one week later than that shown in 

 fig. 122. X I 5- Pinus Strobus. June 6, 1898. 



124. A very young macrospore-mother-cell showing differentiation of 

 spongy tissue. X 394- Pinus rigida. May 15, 1902. 



125. The macrospore-mother-cell from fig. 124 more highly magnified. 

 X8io. 



126. A macrospore-mother-cell just prior to synapsis. X 810. Pinus 

 Strobus. June 27, 1898. 



(178) 



