264 The Ohio Naturalist. [Vol. VIII, No. 4, 



LITERATURE. 



The literature bearing on the morphology of Geraniales is 

 very scarce. The following works bear slightly on the subject. 



Britton, Nathaniel Lord, Manual of the Flora of the Northern 

 United States and Canada. 1905. 



Coulter and Chamberlain, Morphology of Angiosperms. 1903. 



Rosendahl, C. Otto, Preliminary note on the Embryogeny of 

 Symphocarpus foetidus, Salisb. Science N. S. 23: 590. 1906. 



Schaffner, Mabel, The Embrvologv of the Shepherd's Purse. 

 Ohio Nat 7 : 1-8, pis. 1-3, 1906. 



EXPLANATION OF PLATES. 



All drawings were made with a Bausch and Lonib microscope with 

 the aid of a camera lucida. In reproduction they were reduced to one- 

 third their original size. The following combinations of oculars and 

 objectives were used : 



Figs. 1-14, oc. }/2 in-, obj. 1-G in. Magnification 720. 



Fig. 15, oc. 2 in., obj. 1-12 in. Magnification 470. 



Figs., 16 and 17, oc. 2 in., obj. 1-G in. Magnification 205. 



Fig. 18, oc. }/2 ii^-> obj. 2-3 in. Magnification 146. 



Fig. 1. Young ovule with archesporial cell. X 360. 



Fig. 2. Large megaspore with non-functional ones above it. Nucellus 



beginning to disintegrate. X 360. 

 Fig. 3. Two celled embryo sac. X 360. 

 Fig. 4. Four celled embryo sac. X 360. 

 Fig. 5. Seven celled embryo sac with the antipodals completely 



disintegrated. X 360. 

 Fig. 6. Eight celled embryo sac showing entrance of pollen tube hiding 

 disintegrating synergid. Polar nuclei uniting and antipodals 

 beginning to disintegrate. X 360. 

 Fertilized egg and pollen tube. X 360. 

 The three celled pro-embryo. X 360. 



Six celled embryo showing first appearance of the embryo 

 proper. X 360. 



Young embryo showing the octant stage and the division of the 

 central suspensor cell by a longitudinal wall. X 360. 

 Slightly older stage in the growth of the embryo. The central 

 suspensor cell vm divided. X 360. 



Somewhat more mature einbr5^o showing the beginning of 

 dermatogen. X 360. 



More advanced embryo showing the beginning of the multi- 

 cellular suspensor, dermatogen completely differentiated. X 360. 

 Embryo showing the origin of the cotyledons by the bulge on 

 the opposite sides. Foot-like expansion of the suspensor becom- 

 ing prominent. X 360. 



Base of half-grown embryo showing differentiation of tissues at 

 the root tip. X 235. 

 Fig. 1 6. Nearly mature embryo showing different tissues and the multi- 

 cellular base of the suspensor piercing the integuments and 

 reaching the testa. Cotyledons obliquely cut so as to mask the 

 regularity of tissue. X 100. 

 Fig. 17. Haustorium-like region in the base of the suspensor. X 100. 

 Fig. 18. Cross section of seed showing the mature embryo and cor- 

 rugated testa. X 75. 



