6i6 Kny . — On Correlation in the Growth of 
an advance in the investigation of the problem under con- 
sideration. He observed in all cases an evident retardation 
of growth in those parts of the organism which remained free, 
whilst the others were imbedded in gypsum. If the shoot 
were embedded, the root grew more slowly than that of a free 
plant, and vice versa h If the parts which had been embedded 
were freed as carefully as possible from the gypsum, then the 
corresponding root and shoot at once began to grow more 
quickly 2 . Hence the striking independence in the growth of 
roots and shoots of seedlings which was so unmistakably 
shown in my experiments would appear to be, at least in part, 
a result of the stimulus (Reiz) exerted upon the growth of the 
root by the regeneration of the shoot, and vice versa. But 
that this is not the only cause of the independence is clear 
from the observations on willow-cuttings which I have 
published. For although in the case of the cuttings, as in 
that oi tne seedlings, the developing shoots and roots were 
repeatedly removed, their independence of growth was much 
less marked. The experiments performed in 1894 with 
cuttings of Salix acuminata and S'. purpurea were repeated 
by me in a similar manner in the following year with cuttings 
of Ampelopsis quinquefolia . In this case also, sixty-three cut- 
tings about 27 cm. in length were arranged in nine cylinders, 
all of the same cubic contents. The lower ends of the cuttings 
were immersed in water, whilst the upper ends were in the air. 
Three of the cylinders formed one series. The cuttings, whose 
diameter varied from 6 to 11-5 mm., were so distributed, that 
each series included the same number of cuttings of each 
different diameter. 
In Series I the cuttings remained uninjured throughout the 
experiment. In Series II developing buds were repeatedly 
removed with care, whilst the roots were not touched. In 
Series III the developing roots were repeatedly and carefully 
removed, whilst the buds were left untouched. 
The experiments began on April 5, 1895. The operations 
1 Loc. cit., p. 139. 
2 Loc. cit., p. 142. 
