1914] CURRENT LITERATURE 533 
petiole of Mimosa cannot occur over a zone that is dead or in a state of rigor, 
contrary to the claims of HABERLANDT and PFEFFER. As BOSE puts it, con- 
duction of stimuli in this organ is a true “excitatory” or “physiological’’ pro- 
cess. His statement that plant physiologists universally hold that conduction 
of stimuli in plants is ‘“hydromechanical’”’ shows that he has entirely over- 
looked the generally accepted and much quoted classic of Frrrinc (1907) on 
the conduction of the light stimulus in the coleoptile of Avena. The author’s 
ndings in Mimosa do not, contrary to his statement, disprove a universall 
the general situation for plants. He has shown that PFLUGER’s laws of polar 
excitation in animal tissues hold for plant tissues, es supplements these by 
two more laws that hold for strong currents. s only one of many illus- 
trations that Bose brings forward of fundamental fennel in stimulus effects 
and response in plants and animals. Records are given of very accurate 
determinations of latent periods (the time elapsing between application of the 
stimulus to the pulvinus and the beginning of movement) in the leaves of 
Mimosa and other motile leaves, as well as exact measurements of the rate of 
conductivity of stimuli. In the primary pulvinus of Mimosa the shortest 
latent period found was 0.06 second, and the average 0.1 second. In subtonic 
but not in optimum condition of the organ, increased strength of the stimulus 
ao? while in general fatigue prolongs, and a rise in temperature shortens 
this period. The maximum rate = conduction was that found in the petiole 
of imosa; it was 30 mm. per second. Conditions that shorten the latent 
period also increase the rate of ced In subtonic but not in optimum 
condition of the organ, previous application of the stimulus hastens the rate 
of conduction. Conduction takes place in both directions, but not always 
at the same rate. In Biophytum, for instance, the velocity is greater in the 
centrifugal than in the centripetal direction. 
Bose emphasizes that conduction of the stimulus proper is accompanied 
by a wave of contraction and of galvanometric negativity. This is contrasted 
with the wave of galvanometric positivity which passes over a stimulated non- 
which travels much faster than the ay stimulus effect. The author 
emphasizes this distinction between true “excitatory” or “physiological” 
conduction, accompanied by contraction and galvanometric negativity, | and 
the “physical” conduction, marked b galvanometric positivity. 
It now recognizes that the effect and conduction of stimuli proper in the organ- 
ism are physical also, undoubtedly more complex than the behavior in the 
non-living, but physical nevertheless. Two groups of facts, each in part and 
both together, probably fully explain the physics of the contractile wave with 
its galvanometric negativity. One group of workers* has produced much 
7 Science N.S. 37:959-074- 1913. 
