Germination of A rceuthobium Occident ale. 105 
only tissue differentiated. This lies at first in close contact with the 
endosperm, but as germination progresses it is no longer in contact. The 
embryo must therefore absorb dissolved food diffusing out of the endosperm 
into a layer of water which surrounds the embryo. Whether the embryo 
forms enzymes which, diffusing into the endosperm, dissolve the solid foods 
stored therein, or whether the endosperm cells themselves dissolve these 
solid foods, which thereupon diffuse outward toward the embryo, there is at 
present no means of telling. As all attempts at experimental germinations 
have hitherto failed, there is no hope for an immediate answer to the 
question, though an answer might throw an interesting light on the physio- 
logical chemistry of germination in exalbuminous plants. The embryos are 
bright green, and contain much starch, at least in the earliest stages of 
germination. The radicle has no cap at any time, and the tip for some 
distance back, even in the later stages of germination, consists of merismatic 
cells, with only the dermatogen at all differentiated. 
It may be of some systematic value to record that, though quite by 
chance, I found two embryos in one ‘seed,’ as shown by Fig. 14. These 
two embryos are of unequal size, and only one could possibly have developed 
into a new plant. Johnson (1888) records having always found only one 
embryo, but remarks (p. 158) that ‘ the general result of the investigation 
tends to show that in the possibility of the formation of two embryos and 
in habit the affinity of Arcenthobium to Viscum albwn is closer than was 
generally supposed.’ I cannot consider the habit of this species of Arceu - 
thobium at all like Viscum or the allied genus Phoradendron , as will appear 
later on. 
The root does not appear to be geotropic, but as in other Loran- 
thaceae (Pfeffer II. 575, 1900) it is negatively phototropic in marked 
degree, growing always away from the light, down a needle or along 
a branch toward the central and darker part of the tree (see Figures 
15, 1 6, 17). I have never seen a root-tip pointing in any other direction 
than away from the light, and often it was necessary for the root to make 
a turn of over 90° to do this (Fig. 16). I have seen roots turned 180°, 
but in these the curve was always a spiral, downward as well as backward. 
We may have here the influence of gravity supplementing that of light, but 
as the light reaction is so marked and the geotropic reaction so slight, we 
may doubt, until experiment furnishes evidence, whether these roots are 
geotropic at all. In this respect they are like Viscum , the roots of which 
are not geotropic. 
The roots do not appear to be very sensitive to contact. They grow 
generally in fairly close contact with the surface of pine-needles or branches, 
but they do not stop growing and form holdfasts on the needles, though 
the contact with the surface of the needle may be long continued. The 
root may even grow for some distance over the comparatively rough surface 
