igig] SCHERTZ—SCROPHULARIA 449 



10. Only a single thickened integument is found. 



11. Endosperm formation takes place before the fertilized 

 egg divides. Endosperm cells separate the fertilized egg from the 

 micropylar end of the embryo sac. 



12. The embryo develops a short suspensor which disappears as 

 the embryo matures. 



13. The mature seed consists of an embryo surrounded by 

 thickened endosperm cells greatly gorged with crystalline protein 

 and other food matter. 



The writer is indebted to Professor C. B. Atwell, of North- 

 western University, under whom this work was conducted, for the 

 material upon which the work was done, and for his helpful sug- 

 gestions and kind advice. 



Department of Agriculture 

 Washington, D.C. 



EXPLANATION OF PLATES XXVII-XXIX 



Abbreviations used are as follows: a, antipodals; b, bract; c, cotyledon; 

 CO, corolla; d, degenerate nucleus; e, embryo; /, funiculus; h, haustoria; 

 i, integument; j, endosperm; k, micropyle; /, egg; m, megaspore; inc, mega- 

 spore mother ceU; n, nucellus; 0, ovule; oc, ovary cavity; p, pistil; pn, polar 

 nucleus; q, placenta; r, rudimentary flower; s, stamen; st, stigma; sa, stem 

 apex; t, tapetum; ti, protein crystals; v, testa; w, synergid; x, calyx; y, sus- 

 pensor; 3, nutritive tissues. 



AU of the figures were outUned by means of an Abbe camera lucida on a 

 level with the stage of the microscope. The details were drawn in freehand. 

 The microscope used was a Bausch and Lomb with a triple nosepiece. The 

 following combinations were used: figs, i-io, no. i ocular and 16 mm. objec- 

 tive; figs. 11-19, 21, 27,31, 34, and 36, no. 8 ocular and 2 mm. objective; fig. 22, 

 no. 8 ocular and 4 mm. objective; figs. 26, 32, ^$, and 35, no. 8 ocular and 

 16 mm. objective; figs. 23, 24, and 25, no. 8 ocular and 3 mm. objective; fig. 20, 

 no. 12.5 ocular and 2 mm. objective. In all of the figures the micropylar end is 

 toward the top of the plate. Figs. 22, 24, 25, and 35 are each reconstructed 

 from several sections. 



Fig. I. — Longitudinal section of stem apex and young bract before any 

 differentiation has taken place. 



Fig. 2. — Similar section of flower with bract, showing calyx being differ- 

 entiated. 



Fig. 3. — -Similar section of flower showing bract, calyx, and stamens. 



Fig. 4. — Similar section of flower, with calyx and stamens; petals and 

 pistil appearing. 



