288 



PLANT RESPONSE 



Table showing Cyclic Variation of Multiple Responses 



in bloi'hytum and in retina 



Cyclic variation in the periodicity of the 

 multiple response of Biophytum 



Cyclic variation in the recurrent visual 

 impulses 



Interval between 1st Cv. 2nd responses 52" Interval between 1st cc 2nd responses 7" 



2nd ,, 3rd 

 3rd ,, 4th 

 4th „ 5th 

 5th „ 6th 

 6th ,, 7th 



52 



,, 2nd ,, 3rd 



,, 3rd ,, 4th 



„ 4th ,, 5th 



,, 5th ,, 6th 



,, 6th ,, 7th 



5-25" 

 6-5" 



7" 

 9" 

 1 1" 



In both these cases, therefore, we begin with a compara- 

 tively long interval, which grows shorter, and then, again, is 

 progressively lengthened. 



Intermittent pulsation. — We have now dealt with one 

 of the two instances of correspondence between obscure pulsa- 

 tory phenomena in animal and vegetable. The second, which 

 remains to be considered, is that known to physicians as ' the 



Fig. 121. Intermittent Human Pulse (Broadbent) 



intermittent pulse' (fig. 121). ' The term " intermittent " is 

 employed to designate the pulse when a beat is occasionally 

 missing from time to time, while the pulse in the intervals is 

 perfectly regular. It is a remarkable variety of pulse, and is 

 perhaps the least capable of explanation of any. The inter- 

 mission may happen at regular and definite periods, every 

 four, six, or up to twenty beats ; or the number of interven- 

 ing pulsations may vary. The intermittent pulse may be 

 habitual and constant, and in this case is more likely to be 

 at definite intervals, or it may be occasional only, under the 

 influence of some disturbing cause. . . . Occasionally nervous- 

 ness and fatigue will render the intermissions more frequent.' ' 



1 Broadbent, The Pulse, p. 125. 



