Yamih)LSKY: Stiidy oj OU palm. 155 



sliows a side view of a kidney sliaped haustorium and Figure 108 shows 

 oiie with the above described coiistrictioii. A loiigitiidiiial view of sucli an 

 haustorium is seen in Figure 127, Plate XVi. Local inhibition' of growth 

 which aliows the rest of the tissue to grow beyond it caii account for 

 such structures. 



Size of haustorium. 



The ultimate size of the haustorium dépends upon the volume of 

 endosperm tissue that it has to displace since as we hâve seeii ail of the 

 endosperm is absorbed, The great variation that exists in the size of the 

 endosperm in the varions types of fruits and within the fruits of one tree 

 influences the ultimate size of the haustorium. The présence of two or 

 more enbryos in a seed likewise influences the size of the individual 

 haustoria. Thus we see that the liaustoria in a fruit with two or three 

 embryos (Figures 103 and 104, Plate XI) are half as large as those in fruits 

 with one embryo (Figure 102), although ail tliree types are in the same 

 stage of development. The largest haustorium is found in the so-called 

 macrocarya form and the smallest would occur in the pisifera form if 

 germination of suçh a form were assured. A glance at the types of fruit 

 shown in Plate Vlil brings out the variations that may exist in the size of 

 the haustorium of the oil palm. 



The rôle of the cells of the haustorium and the endosperm duriiig 

 germination was for the first time described by SACHS (•'"), (•^') and in 

 order to orient ourselves on the many problems that are before us, a digest 

 of his work on grasses and the date palm will be of material aid. 



In the grasses the following salient features may be noted. 



Between the endosperm and the shield (scutellum) a layer of crushed 

 cells is présent — thèse are the remains of endosperm cells. 



Parenchyma cells of the shield show inter-cellular spaces. 



No changes occur in the parenchyma cells during the whole process 

 of germination; the shield is fully developed in the resting condition of 

 the embryo. 



Before germination no sugar is found in the endosperm and the starch 

 grains are intact. 



When the root in the wheat seediing is 1 cm. long and in corn 3 cm. 

 long, the présence of sugar can be detected associated also with corrosion 

 of starch grains. 



The process begins where the endosperm is in contact with shield 

 and then digestion moves slowly to remoter parts of the endosperm. 



The parenchyma of the seediing becomes filled with starch grains. 



Neither sugars nor starch are présent in the epithelium (ferment layer) 

 of the shield (scutellum) at any time during germination. The sugars that 

 pass from the endosperm into the shield through the epithelium are either 

 fixed by the nitrogenous substances in the cells or they are immediately 



