I'fIE PILYYIOLOQY OF ASCIDIANS
49
frequency of contractkms iR fiiirly uniform in any given animal.
Several workem have notcd, howevw, that the frequency of advisceral
beating is usually slightly grent,er thuri for abvisceral beating (Hecht,
1918c ; Skramlik, l926a, 1930 ; Anderson, 1968 ; Kriebel, 1968a) (Fig.
15).
30
10
T
S
e
S
e
B
v
Fio. 15. Tho average frequency of Nixteen incilated hearta at the start and end of
branohial (B) and viscoral (V) pulsation-series. The rango is shown by the oentre line
ineaoh bar. s, &art of mrios; e, end of series. (Redrawn from Kriebel, 1968a.)
No matter which way the heart beat is travelling the wave of
contraction norni;dly starts at oiic end of the heart and travel8 to the
other but occavionally uriclrr almormul conditions a wave may comnience at fhc ccwtrc of the Iicart! iuld pass simulta~ieoi~~ly to either end
(Hecht, 1 9 1 8 ~ ;
Hkrctrnlik, I!)2h; Andtmon, 1968). Brow8 rl d. (1966)
49
frequency of contractkms iR fiiirly uniform in any given animal.
Several workem have notcd, howevw, that the frequency of advisceral
beating is usually slightly grent,er thuri for abvisceral beating (Hecht,
1918c ; Skramlik, l926a, 1930 ; Anderson, 1968 ; Kriebel, 1968a) (Fig.
15).
30
10
T
S
e
S
e
B
v
Fio. 15. Tho average frequency of Nixteen incilated hearta at the start and end of
branohial (B) and viscoral (V) pulsation-series. The rango is shown by the oentre line
ineaoh bar. s, &art of mrios; e, end of series. (Redrawn from Kriebel, 1968a.)
No matter which way the heart beat is travelling the wave of
contraction norni;dly starts at oiic end of the heart and travel8 to the
other but occavionally uriclrr almormul conditions a wave may comnience at fhc ccwtrc of the Iicart! iuld pass simulta~ieoi~~ly to either end
(Hecht, 1 9 1 8 ~ ;
Hkrctrnlik, I!)2h; Andtmon, 1968). Brow8 rl d. (1966)