now in press (http://www.peeters-leuven.be/boekoverz.asp?nr=9120 - I join for information a special list of Indological books published in this series. A reprint of Lamotte's Sa.mdhinirmocanasuutra with a new introduction by H. Durt is planned).

So, for answering Karp's question on the basis of Smets' researches : 

The verb mūrch is used in JaiSa 47.7:

p.rthivyaadi.su bhuute.su muurchito dhaatur antima.h |

sa.mti.s.thati draviibhuuta.h prathame maasi garbhaga.h ||

Cf. YajñS III.75 and Mit. ad loc.

(Smets states that muurch should be here rather translated by "expanded", "increased" or "filled" with, viz. "mixed")

and also the Pari/si.s.ta ad Vaaraaha/srautasuutra xxvi.1 (cf. P. ROLLAND, 'Un fragment médical “ védique ” : Le premier khaṇḍa du Vārāhapariśiṣṭa Bhūtotpatti', in Münchener Studien zur Sprachwissenschaft 30 (1972), p. 129-138):

tad vaayu/s ce.s.tayaty aakaa/se cetanaadhaatu.m muurchayati

Best wishes,

Christophe Vielle