Nature of the Tumbling Propensity. 
197 
which we think is just, between it and the tremulous “motion” in the neck of the Fantail ; and 
the sequence of an involuntary performance by the poor Indian birds upon what is obviously a 
slight concussion or rather irritation of the brain, is too striking a parallel to the involuntary 
performances of “Mad Tumblers” to require more than pointing out. We need hardly remark, 
however, that it by no means follows all tumbling is involuntary, as we have often seen very' 
foolishly argued. The line between voluntary and involuntary is never very definite, as shown for 
instance in the case of a fit of hysterics, which in hundreds of known cases is entered upon in a 
perfectly voluntary manner, but afterwards becomes beyond the control of the foolish patient. So, 
again, many individuals have sensibilities, not shared by the average of mankind, which yield 
them the most exquisite pleasure, but which, only a little more exaggerated, occasion others 
the most exquisite pain : and thus also we see no reason to doubt that the wonderful aerial 
performances of the Tumbling pigeon, while the propensity which causes them may be so 
exaggerated as to be a source of misery, yet in ordinary may yield the bird all the real pleasure 
which it so evidently appears to do. 
