165 
Part IV.] Rama Rao : lloit Plants of the Sandal Tree. 
of the haustoria of sandalwood on the roots of numerous species 
of host-plants appear to have led him to a similar conclusion.^ We 
may then take it, for the purposes of practical sylviculture, as a 
settled fact that sandalwood shows a decided selective 'power in 
choosing its hosts, and that it derives its nourishvient more abund- 
antly from certain species than from others. 
G. This leads us to the next question — what are the species that 
form the best hosts of Sandalwood'? To answer this question fully 
and satisfactorily ,^an exhaustive study of the root-systems of all the 
species of plants indigenous in all the sandal areas of India and of 
their influence on the growth of this tree appears necessary. More- 
over, a careful examination under the microscope of the sandal 
haustoria on the roots of its numerous associates may also be found 
necessary for ascertaining to what extent the haustoria successfully 
penetrate the woody portions of the hosts, as, without such penetra- 
tion, sandal appears to derive little or no nourishment from them, 
even though it forms root-connections. The results of Ilr. Barber’s 
investigation under the microscope haA"e been published in the 
Memoirs of the Department of Agriculture in India in two parts 
under the title “Studies in Root-parasitism. The Haustorium of 
Santalum album.” 
7. This most valuable and useful work does not deal with the 
haustoria formed on all the species associated with the sandal as 
Dr. Barber examined them only on 89 species, while the number 
of associates exceeds 250 — including exotics with which sandal wood 
is found to grow in gardens. Microscopical examination of the 
haustoria on some of the associates may be dispensed with, as the 
best practical test of successful penetration is afforded by the scars 
visible to the naked ej^e, of fallen-off haustoria on the woody portions 
of the roots attacked. In some cases, such scars are covered over 
by the formation of callus or new growth from the cambium, leav- 
ing only a .superficial trace of sandal attack, for example, roots of 
Albizzia odoratissima and Pongamia glabra, but in such cases a cut 
with a knife may disclose the depth to which the haustorium had 
penetrated. Again, in some ca.ses, such as the green aloe (Four- 
croya gigantea), no penetration into the woody central cylinder may 
be discovered under the microscope, the progre.ss of the haustoria 
’ “ The haustoria of Sandal roots ” by Dr. Barber. — Indian Forester, 
Volume XXXI, page 190. 
