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RULES OF RITUAL INTERPRETATION 95
Elaborate rules are accordingly given in Adhyāya IX of the Sūtra on this head. Nor only Mantras are altered, but also Sämans; thus at the Vaisyastoma the Kanvarathantara replaces the oiginal Bșhat and Rathantara Sãmans. In some cases purifications are modified; thus the wild rice (nīvāra) used at the Vājapeya offering, in place of the ordinary rice, is subjected to the processes of purification applicable to the latter, In other cases Mantras are not altered, but the number of times of their use is modified.
In other cases the transference must be accompanied by the annulment of details which are now inappropriate. The cases in which this occurs, enumerated in Adhyāya X, are numerous and complicated; thus an act may by change be rendered useless; in the Prājāpatya rite, based on the pew and full moon sacrifices, grains of gold replace rice
grains, and the operations of husking and washing are * therefore annulled. Again, if Yajus Mantras are given to be recited as Nigadas, which are invitations and therefore must be said aloud, the normal rule of muttering of Yajus Mantras is annulled in favour of the necessary loud utterance. Annulment, again, may be partial or complete, and the later text books take special pleasure in developing the diverse forms in which it may appear. Opposed to annulment is combination (samuccaya) in which the new details of the derivative form are only added to the details of the original offering.
In Adhyāya XI the question is raised of the relation of subsidiary to principal offerings as regards repetition of performance. In certain cases a single performance of subsidiaries gives effective aid to more than one principal action, as in the case of the Agnyädhāna, which need only once be performed, the same consecrated fire serving for all subsequent sacrifices; this aid is styled Tantra. On the other hand, some subsidiaries must be repeated with each principal offering ; thus the subsidiaries of the rites performed at new and full moon respectively in those offerings are nearly the same, but the lapse of time between the two rites renters the repetition of the subsidiaries essential, this case is styled Avāpa. But in some cases where a subsidiary is merely performed for the purpose of aiding one
