358 BOTANICAL GAZETTE [ay 
The positive response of fern sperms to the archegonium and to 
the salts of malic acid is too well known to need description. This 
is believed by most authors to be due to the directive action of the 
stimulating substance on the motor organs, the axis being thus 
turned toward the stimulant. Most workers, however, while hold- 
ing this view, have noted that many sperms do not react as thus 
described, but may wander about the field, or pass through it indiffer- 
ently, or may avoid it. Such reactions have been ascribed to indi- 
vidual differences. 
Thus Jost (21, p. 542) states that “whenever they (the sperms) 
come into the neighborhood of an archegonium, they twist sharply 
round, so as to direct their anterior ends toward the mouth of the 
archegonium; they thus rapidly approach it, enter its neck, and fuse ~ 
with the ovum in the interior.” In describing experiments with 
malic acid, Jost states (21, p. 542): “It may be clearly seen that the 
sperms curve around sharply the moment they come within the sphere 
of influence of the malic acid diffusing out of the tube, and place 
their long axes parallel with the course of the diffusion current. 
Without any acceleration of their movements they then steer their 
way toward the more concentrated solution straight for the mouth 
of the tube. Since the sperms distribute themselves equally in 2. 
homogeneous solution of malic acid, just as they do in water, we are 
bound to regard the unequal distribution of the acid as the directive 
stimulus.” 
The question before us is: Are the movements of fern sperms 
best explained as being due to the local action of different concentra- 
tions of a stimulant on different parts of the body, thus producing 
movements leading to an orientation of the axis; or are they to be 
regarded as the result of the action of the stimulant on the organism 
as a whole, the resulting movements being such as to take the organ- 
ism toward the region of optimal concentration ? 
In the present investigation a few observations were made on the 
reactions of sperms to malic acid in capillary tubes, but most of the 
results on positive responses were obtained from the reaction of the 
sperms to the substance extruded from the archegonia of either the 
same or of different species. In such cases the prothalli bearing 
the antheridia and the archegonia were rinsed and placed in water 
