186 Thompson .— The Relationships of the 
Reticulate perforations of this type appear to be quite different from 
those described above as frequently accompanying the scalariform type. 
They show no trace of the scalariform condition. It is, of course, conceivable 
that they are of the same nature as those previously described, and that the 
reticulation of the latter has gone much farther and the individual pores 
rounded up. In Tropaeolum one sometimes finds perforations approaching 
the Cordia type along with more numerous ones which are nearly scalari- 
A, Vessel from Tecoma radicans. 
C, from Bougainvillea speciosa. 
b and Fig. 
A-d. Scalariform-reticulate perfora¬ 
tions from Tropaeolum. 
A Jri 
f 
Fig. 6. Vessels from Cordia 
callacosa , A showing evidence 
of the loss of reticulations. 
Fig. 7. a-f. Stages in the disappearance 
of reticulate perforations in Potentilla mon- 
speliensis . 
form (Fig. 5). But the origin and relationships of the different types will 
be discussed in later paragraphs. 
In some cases there is evidence that the reticulate perforations of the 
Cordia type have disappeared and given the simple type. Appearances 
such as Fig. 6 , a, are common next to the pith in Cordia callacosa. The 
scalloped edge of the perforation appears to be the result of the loss 
of a net. A similar perforation is shown in Fig. 4, C, drawn from Bougain¬ 
villea speciosa. In these forms I have never seen any evidence of the 
individual pores of the net fusing ; apparently the whole net is lost at once. 
In some species a very irregular net appears to be associated with 
a fusion of perforations, as pointed out by Miss Bliss. Such conditions may 
be found in certain members of the Rosaceae, and are illustrated in Fig. 7 
from Potentilla monspeliensis , and in Fig. 8 from Cydonia. Somewhat 
