4 The Ohio Naturalist. [Vol. VII, No. 1, 



cells of the hypocotyledonary region and root tip undergo rapid 

 division so that the entire length of the cavity of the ovule is 

 filled and the suspensor cells are crushed (Figs. 35, 37). But 

 the vesicular cell retains its active appearance to the end. 



The plerome consists of a bundle of small elongated cells 

 surrounded by a sheath of larger cells and the periblem consists 

 of two layers with an inner limiting layer. The sheath of the 

 plerome and the inner layer of the periblem have a common 

 origin as will appear from an inspection of Figs. 36 and 38. The 

 nature of these two layers was not determined. In the mature 

 embryo the cotyledons are w^ell developed but it is difficult to 

 obtain central sections because of the curving and folding. 

 Usually when one has a central section of the radicle the sections 

 of the cotyledons will be more or less tangential. 



ADDENDUM. 



The foregoing paper was left in an incomplete condition at the 

 time of my wife's untimely death. It was her desire to w^ork out 

 the embryogeny of Bursa step by step as a preliminary to other 

 embrylological studies which she had begun. However, the 

 work was so nearly complete that it was thought advisable to 

 publish it as it w'as left although a few spindle stages are lacking 

 for a complete series. Just before her last sickness she had pre- 

 pared material collected at various times of the day and night 

 in the hope of being able to fill out the missing stages. 



The series of figures, all drawn on the same scale, represent 

 to the eye the actual increase of the embryo in size at each stage 

 of development and will be of considerable use to students for 

 reference. 



To be cut off in the midst of work and plans for the fviture 

 was her sad lot, and, without referring to my personal loss, it is 

 with a sorrowful heart that I contemplate her passing away so 

 long before her bright hopes and ambitions were realized. 



John H. Schaffxer. 



LITERATURE. 



1. Hanstein, J. Entwickelungsgeschichte der Keime der 

 Monocotvledonen und Dicotvledonen. Bot. Abhandl. Bonn, 

 pp. 112,'lS7(). 



2. Famixtzin, a. Embrvologische Studien. Mem. Acad. 

 Imp. Sci. St. Petersbourg 26:10, 1S79. 



3. Riddle, LuMiXA C. The Embrvologv of Alvssum. Bot. 

 Gaz. 26:314-324, ISOS. 



4. Coulter, |. M., axd Chamberlaix, C. J. Morphology 

 of Angiosperms. p. H)(), H)l)3. 



o. Chamberlaix, C. J. Methods in Plant Histologv, p. 

 223. 1005. 



