The acoustic detection of cavitation in fern sporangia
1990
Ritman, K.T. | Milburn, J.A.
Cavitation of water in the annular cells of fern sporangia was monitored simultaneously by acoustic detection and visual analysis using a light microscope. The number of cavitable annular cells was found to be 21.3 +/- 1.7 (n = 40). The number and timing of ultrasonic acoustic emissions (UAE) received from a fully hydrated sporangium allowed to dehydrate on the acoustic probe closely approximated the average number of cavitable annular cells. The number and timing of audible acoustic emissions (AAE) was found to be lower than the number of UAE. AAE were associated with cavitation-induced forward movements of the sporangium rather than individual cavitation events within each annular cell. The results are discussed in view of an hypothesis proposed by Ritman and Milburn (1988) which describes the relationship between the frequency of acoustic emission and the size of the resonating element.
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