544 Butter.—Contributions to our Knowledge of the 
burger 1 during the entrance of spermatozoa into the arche- 
gonia of Ferns and Marchantia , by Hanstein 2 at a similar 
moment in the case of Marsilia , and by Fischer 3 in the 
approach of the swarmspores of certain Fungi parasitic on 
Saprolegniae toward their hosts, while Engelmann 4 had 
determined that the unequal distribution of oxygen conditions 
the movements of Bacteria, &c. towards air-bubbles or towards 
a zone in the medium where the oxygen has a particular 
pressure. The collections of Infusoria and Bacteria at the 
surface of decaying organic matter observed by Leeuwenhoek, 
O. F. Muller, Ehrenberg 5 and Cohn 6 were also probably in 
part at least due to chemotaxis 7 . 
Stahl 8 has found that the plasmodia of the Myxomycetes 
respond to chemotactic stimuli. Massart 9 and Bordet have 
shown that this is also true of the leucocytes of the blood. 
Pfeifer’s experiments were made by a method 10 at once 
ingenious and simple. Capillary glass tubes about 8 mm 
long and y 1 ^ mm internal diameter are closed at one end in 
a gas flame and then placed in a watch-glass. The solution 
to be tested is poured over the tubes and the watch-glass 
thereupon set under the bell of an air-pump. On reducing 
1 Strasburger, Jahrb. f. wiss. Bot., 1869-70, Bd. vii, pp. 402 and 418. 
2 Hanstein, Jahrb. f. wiss. Bot., 1865-6, Bd. iv, pp. 219 and 220. 
3 Fischer, Jahrb. f. wiss. Bot., 1882, Bd. xiii, p. 303. 
4 Engelmann, Bot. Zeit., 1881, p. 440. Pfliiger’s Archiv f. Physiologie, 1881, 
Bd. xxv, p. 288 ; also Bd. xxvi, p. 541. 
5 Ehrenberg, Die Infusionsthiere als vollkommene Organismen, 1838, pp. 79 
and 80. 
6 Cohn, Beitrage zur Biologie d. Pflanzen, 1872, Bd. i, Heft 2, p. 142. The 
observations of Leeuwenhoek and O. F. Muller are here cited. 
7 Note. —The collecting of spermatozoa around the egg-cells of Fucus which 
was observed by Thuret (Annales d. sci. nat., 1854, 4® ser., tome ii, p. 210) 
may also be a chemotactic phenomenon. Strasburger’s observations appear to 
support this supposition (Das bot. Prakticum, 2. Aufl., 1887, P- 402)- Bordet 
however denies that the spermatozoa are chemotactic (Contribution a l’etude 
de Pirritabilite des spermatozo'ides chez les Fucacees, Bull, de l’Acad. Belgique, 
3® sdr., tome xxvii, 1894, p. 889). 
8 Stahl, Zur Biologie der Myxomyceten, Bot. Zeit., 1884, p. 165. 
9 Massart et Bordet, Recherches sur Pirritabilite des Leucocytes, Soc. royale des 
sc. med. et nat. de Bruxelles, 1890. See also Gabritchesky, Sur les proprietes 
chimotactiques des Leucocytes, Ann. de l’lnst. Pasteur, 1890, p. 346. 
10 Loc. cit., Bd. i, p. 367. 
