116 Trails. Acad. Sci. of St. Louis. 



Mattirolo and Buscalioni ascribe a physiological function to 

 the tracheid island during the early stages of germination. 



We may now consider the ecological relations of the 

 structures adjacent to the funiculus. One of the most im- 

 portant of the appendages is the aril. In the immature seed 

 it is intimately connected with the funiculus. The studies of 

 Pfeiffer (200) show that these basal, appendaged structures 

 of the funiculus occur in some Leguminosae hitherto regarded 

 as being without an arillus. In Pisum it remains attached to 

 the placenta and does not cover the micropyle. In the second 

 type the micropyle is frequently covered or the hilum is sur- 

 rounded by a thickened border or rim, as in Mucuna pruriens. 

 In some of the Leguminosae the funiculus, together with the 

 arillus, has an important function to perform in the separa- 

 tion of the seed from the pod (Bachmann 4. Wiesner 285). 

 In a young fertilized ovule of Pisum or Phaseolus the funic- 

 ulus is very large, the former rapidly increases in size, and 

 in full active period of growth the latter is small compared 

 with the immature seed. In Mucuna pruriens the arillus, the 

 bordered base of the funiculus, becomes an important 

 strengthening organ. It consists of a series of thick-walled 

 sclerotic cells. On the outside these cells are shorter than 

 within, and at the base curve inward. The remainder of the 

 cells curve obliquely upward. The sclerotic rim is wider at 

 the lower end than above, where the cells are shorter and pass 

 into short epidermal cells provided with pores. 



The basal part of the funiculus consists of very large thin- 

 walled and highly turgescent parenchyma cells. Immediately 

 above the tracheid island and below these turgescent cells, a 

 few layers of narrow, elongated, and much smaller paren- 

 chyma cells occur, which undoubtedly are the conducting 

 elements. Now what takes place during the ripening period? 

 The contents of the parenchyma elements are discharged, the 

 thin-walled, turgescent parenchyma cells collapse, and the 

 funiculus is practically separated from the seed. The final 

 process of complete separation occurs when the pod contracts, 

 owing to drying out. The arillus falls in and helps to pinch 

 the seed off. This piuching-off process is especially marked 

 in the funiculus of Pisum. In Mucuna p>ruriens the pinching- 



