6 14 Kny. — On Correlation in the Growth of 
of time, and not the detailed steps by which the final result 
was brought about. The independence in growth of root and 
shoot is not, he thinks, found to be so complete, if the growth 
of the root be investigated immediately after the removing of 
the shoot. The author refers to some unpublished investiga- 
tions by Stone, made in the Botanical Laboratory of the 
University of Leipzig, who observed at short intervals the 
growth of, for instance, the root of a Vieia-seedling, at first 
under normal conditions, the seedling not having been 
deprived of any of its parts ; the observations were made 
by means of a horizontal microscope provided with a micro- 
meter. The increments of growth were expressed in the form 
of a curve, and showed the normal course. After a period of 
observation under these conditions, Stone cut off the shoot 
of the seedling. The effect of this at once became evident in 
a retardation of the rate of growth of the root, the curve rising 
less steeply. The time required for the manifestation of this 
reaction naturally varied in different cases, as did also the 
period of the retarded growth. Retardation was followed 
by vigorous growth connected with the reparatory activity 
at the wounded surface where the shoot had been removed. 
Indeed, the accelerated growth of the root was sometimes 
such, that it not only regained the whole of the retardation, 
but became more rapid than that in a normal, uninjured 
seedling. 
In all cases removal of the shoot caused temporary retarda- 
tion in the rate of growth of the root. These observations, 
according to Hering, show that so high a degree of independ- 
ence in growth as was asserted by Kny, on the evidence of 
the ultimate phenomena of growth, dees not exist, although 
it is possible for the seedling to develop the shoot without 
a root-system, and vice versa , to a considerable extent, so long 
as there is a sufficient supply of reserve material. 
It is clear that Hering had not considered the question as 
to whether or not the retarded growth of the root following 
upon the removal of the shoot was the result of the injury 
temporarily disturbing the development of the organism, and 
