320 The Ohio Naturalist. [Vol. V, No. 6, 



DEVELOPMENT OF THE EMBRYO SAC AND EMBRYO OF 

 STAPHYLEA TRIFOLIATA.* 



Ll'MINA C. RiDDLK. 



Material for the study of Staphylea trifoliata, L. was collected 

 along the banks of the Olentangy River during several Springs, 

 killed in chrome-acetic acid and imbedded in paraffin. The sec- 

 tions prepared varied in thickness from S-15 microns. Analin 

 safranin and gentian violet, and iron-alum haematoxylin were 

 used in staining, both giving good results although the latter 

 stain was too dense for pollen grains. 



Staphylea trifoliata l)e]ongs to the Family Staphyleaceae and 

 to the Order Sapindales and is thus allied to the Hippocasta- 

 naceae, Aceraceae, Celastraceae, and Sapindaceae. Scarcely any 

 morphological work seems to have been done on this Order so 

 that very little comparison can be made between Staphylea and 

 nearly related plants. Mottier, Bot. Gaz. 18:o75-o77, has 

 reported on the development of the embryo-sac of Acer rubrum 

 and some points of comparison will be noted later. Strasburger 

 also made ol)servations on Staphylea pinnata and Acer in 

 " Zellbildtmg and Zelltheilung" Jena, 1880; and " Neue Unter- 

 suchungen ueber den Befruchtungsvorgang bei den Phaneroga- 

 men" Jena LS84. 



As a general rule the flowers were quite normal in the num- 

 ber of parts the only variation being four carpels instead of three 

 in the gynoecium. The number of ovules in each carpel may be 

 as high as eight but very rarely more than one matured in each 

 cavity and often only one in the entire capsule. The ovules are 

 anatropous and the best sections were those cut across the 

 ovulary. As soon as the ovules were large enough they were 

 removed from the capsule before killing. The integuments 

 become too woody to make microtome sections long before the 

 embryo is mature. There are two integuments on the ovule but 

 no aril. 



The hypodermal archesporial cell (PI. 11), Fig. 1) appears 

 l)efore there are any traces of integuments. In one case a three 

 celled archesporium (Fig. 2) was found. The single archesporial 

 cell cuts off a primary parietal cell (Fig. 3) which divides to form 

 from three to five tapetal cells (Figs. 4-7) forcing the mega- 

 sporocyte deep into the tissue of the nucellu^?. The megasporocvte 

 then divides into four megaspores (Fig. 8) and the lowest becomes 

 functional destroying the others as it enlarges and divides 

 (Figs. 9-10). 



* Contriliul inns fi"i)in tlic Butanical Laboratory of the Ohio State Uni- 

 versity, XIX. 



