1919] SCHERTZ—SCROPHULARIA 445 



haustoria. Westermeyer, as reported by Balicka-Iwanowski, 



says that the antipodals of the Scrophulariaceae are particularly 



difficult to verify. 



Embryo 



After fertilization the fertilized egg recedes somewhat from the 

 micropylar end of the embryo sac. The first division takes place 

 transversely. It is followed by a longitudinal division in the chala- 

 zal cell only. The micropylar cell next divides transversely, giving 

 rise to the first suspensor cells. The two cells of the embryo now 

 divide to form the quadrant stage (fig. 28). The two suspensor 

 cells divide (fig. 34) to form a linear row of four cells, which was the 

 largest number observed. The embryo continues to develop in the 

 normal way to form the mature dicotyledonous type (fig. 35). At 

 no time in its development was the embryo observed to be attached 

 to the micropylar end of the embryo sac by an enlarged basal cell, 

 common in dicotyledons. The embryo of Plantago maritima is 

 very similar to the one just described. 



Haustoria 



In the lower central part of the embryo sac, the secondary endo- 

 sperm nucleus divides to form endosperm. When the endosperm 

 nucleus has divided to form four cells (fig. 24), the two chalazal 

 cells assume the character of haustoria. The nuclei in them at 

 first (figs. 24, 25) are very prominent, but later seem to degenerate 

 (fig. 29), and when the embryo is fully formed the haustoria them- 

 selves entirely disappear. 



When the two remaining endosperm cells divide further, they 

 produce four prolongations, which are the micropylar haustoria. 

 These four haustoria are cut off when the endosperm has four 

 cells in cross-section (fig. 25). They may be regarded as absorbing 

 and conducting organs for the transport of food to the rapidly devel- 

 oping endosperm from the surrounding tissues. They are gorged 

 with food matter and react strongly to Delafield's haematoxylin 

 stain. Thickenings of the protoplasm occur in the older haustoria, 

 and may be considered as degenerating nuclei. The nutritive cells 

 of the ovule at the chalazal end of the embryo sac, it may be inferred, 

 are disintegrated by enzymes secreted by the haustoria. Of the 



