134 
Scientific Proceedings (44). 
possible to make various tissues grow in culture media outside of 
the body, in the therrnostat, as well as inside the body, in the latter 
case the body acting as a thermostat. Inasmuch as he noted that 
the epithelial and also connective tissue cells grew preferably in 
contact with solid structures as fibres of fibrin, and into solid gela- 
tinous material rather than into fluids he attributed stereotropic 
sensitiveness to various tissue cells, and he consequently employed 
more or less solid culture media as agar and coagulated blood serum 
for his various experiments. At first he carried out experiments in 
vitro as well as experiments in which the animal body acted as an 
incubator. Lack of the necessary facilities made it very soon 
necessary for him to limit himself to the latter kinds of experiments. 1 
To our knowledge in these our earlier experiments for the first 
time the attempt was recorded in the literature to grow tissues of 
higher animals under artificial conditions in environments that 
differ from those found in the body under natural conditions, 
to separate experimentally growing epithelial from connective tis- 
sue cells, and furthermore to study the influence of the addition 
of certain chemicals upon the growth of tissues. 2 Thus among 
other facts it was found that epithelial cells can grow in these 
gelatinous culture media even after addition of certain salts; that 
this growth can take place independently of connective tissue 
cells, that the epithelial cells may divide mitotically in the culture 
media, that they invade the coagulum through ameboid move- 
ments, that they have the power of phagocytosis, taking up into 
their body small particles of the culture medium; 3 that the growth 
ceases after this period of activity, and we explained on the basis 
of our observations certain phenomena of cancer growth as due 
to active ameboid ingrowth of cancer cells into the deeper tissues. 4 
Later Harrison 5 showed in most interesting experiments that it 
is possible to grow embryonic nervous tissue of the frog in a mix- 
ture of fibrin and serum of the frog lymph, and recently Burrows 
Chicago, 1897; Archiv f. Entwicklungsmechanik, Bd. XIII., 1902. The Journal 
of Medical Research, Vol. VIII., 1902; Journal Am. Med. Association, 1901. 
2 Zeitschrift f. Krebsforschung, Bd. V., 1907, pp. 14 and 15. 
3 Archiv f. Entwicklungsmechanik, Bd. XIII., 1902. 
4 Johns Hopkins Hospital Bulletin, January, 1898. 
Proceedings Soc. Exp. Biol, and Med., Vol. III., 1907; Journal Expert- 
menial Zool., Vol. IX., 1910. 
