1895. ] Development of Botany in Germany. 199 
which take place at the vegetative point have lost the im- 
portance which was once attributed to them; for Sachs has 
shown that the arrangement of the elements at vegetative 
points is not of morphological significance, but is controlled 
by mechanical conditions. 
Schleiden’s investigations into the formation of the embryo 
of phanerogams, which date from the year 1837 on, led 
him curiously astray. He considered that the embryo orig- 
inated from the tip of the pollen-tube, and that the ovule 
was merely the place in which it was further to develop. If 
this were so, then there would be no sexuality in plants, and 
a comparison with the phenomena of fertilization in the ani- 
mal kingdom would be quiteout of the question. Schleiden’s 
views found warm defenders, but in 1849 Hofmeister came 
out clearly in opposition to him, in a very comprehensive 
work. (Amici, in Italy, had already in 1842, taken such a 
stand). Hofmeister proved beyond controversy that the egg 
(germinal-vesicle) was already formed in the ovule, and 
that it was fertilized by the contents of the pollen-tube. He 
did not arrive at the current notion of the structure and phe- 
nomena of the sexual apparatus. These were first made 
clear by Strasburger in 1877. In the same paper Stras- 
burger showed also that the hitherto supposed cases of parthe- 
nogenesis among phanerogams were due tothe adventitious for- 
mation of embryos by non-sexual branching of the nucellar 
tissue into the cavity of the embryo-sac. Since the num- 
ber of such branchings is indefinite, it is at once evident 
why, in the supposed cases of parthenogenesis, polyembryony 
is socommon. Two years before (1869) it had already been 
demonstrated by Strasburger that the so-called corpuscula of 
the Conifere are true archegonia, and that their contents rep- 
resent a single egg. 
In 1880 KARL FRIEDRICH SCHIMPER (a scientific man who 
occupied no public office,and who died in 1867, at Schwetzing- 
en) established the new theory of phyllotaxy, which attracted 
due notice, and became further developed and carried to for- 
mal completion in the writings of ALEXANDER BRAUN (Frei- 
burg, Berlin, died in 1877). This theory assumed, in conse- 
quence of Braun's idealistic conception of nature, the form 
of abstract principles which controlled the processes of devel- 
opment in the body of the plant. Hofmeister was the first, 
in 1868, to attempt to explain the observed regularity in the 
