1895. ] Anatomical and Physiological Researches. 499 
have also been made by Beyerinck,® who inoculated young 
leaves of Salix purpurea with the contents of the vesicle of 
Nematus viminalis, but without being able to produce the 
corresponding nematus-gall. One result was gained, how- 
ever, which also confirms the correctness of Beyerinck’s ob- 
servations, viz., that neither the puncture itself nor the irri- 
tation which it causes to the plant is the real causé of the 
development of the gall, but that the larva of the animal or 
the fungus spore is the factor which produces the gall. It is, 
therefore, not difficult to prevent the development of a gall, 
and this can be done by killing the larva before the gall has 
reached its full size. 
The author gives the history of the development of a num- 
ber of galls from various species of wild roses, oaks, etc., 
and a systematic classification of the galls. This classifica- 
tion depends upon whether the galls are free or immersed in 
the plant; whether they contain one or more embryos; and 
according to the host, whether this belongs to the angio- 
sperms, the conifers or the ferns. The occurrence of tannin 
in the galls is discussed at length, and there are many other 
points of interest in the work, so that it forms a welcome 
contribution to the study of vegetable galls in general.— 
THEO. HoLM. 
The combined effects of geotropism and heliotropism.’ 
standing upright meanwhile. On the other hand plants which 
were first given a heliotropic stimulus were greatly delayed in 
their reactions to a geotropic stimulus given later in an op- 
posite direction. In the extension of the experiments plants 
were subjected to these two stimuli in every position from 
_* Beyerinck, M. W.: Beobachtungen fiber die ersten Entwickelungsphasen 
einiger Cynipidengallen. Amsterdam 1882. Also: Ueber das Cecidium von 
Capree auf Salix amygdalina, Bot. Zeit. 46: 1-11,17-28, 188% 
7F. Czapek, Ueber Zusammenwirken von Heliotropismus un tropismus. 
a d. Sitzungsber, d. kaiserl. Akademie d. Wiss. i. Wien. math.-naturw. Classe 
s—. Mr 1895. 
