304 PHYSIOLOGY [Box. Absts., Vol. VII, 



ligation of the tonic stimulation of various motile cells by light and carbon dioxide. The 

 following were found to be negatively photokinetic in the sense in which Engelmann employed 

 the term, that is, underwent light rigor when illuminated but continued for a relatively 

 long period in darkness: 2 species of Phacus, 2 species of Chlamydomonas, and the zoospores 

 of Ulothrix subtilissima. Chlamydomonas variabilis, Carteria ovata, Euglena gracilis, species 

 of Trachelomonas, Volvox aureus, Pandorina Morum, Eudorina elegans, Gonium pectorale, 

 and Lepocinclis texta were found to be positively photokinetic organisms, a category to which 

 heretofore only the purple bacteria were known to belong. Light was found to be without 

 influence upon the motility of Euglena hyalina, Chilomonas curvata, Menoidium incurvum, 

 Polytoma uvella, Polytomella agilis, and Euglena proxima. Some observations indicate that 

 dark rigor is closely related to the cessation of photosynthesis, but in certain cases, as in 

 that of Chlamydomonas variabilis, there seems to be no relation. No instance of change 

 from positive to negative kinesis after long and intense illumination, such as was reported 

 by Engelmann for the purple bacteria, was observed by the author. Of 19 photokinetic 

 organisms 17 were found to be phototactic, and of IS phototactic organisms 17 were photo- 

 kinetic. In Volvox aureus, Euglena gracilis, Trachelomonas, Eudorina elegans, Chlamydo- 

 monas, Pandorina Morum,, Euglena hyalina, Euglena acus, and Menoidium incurvum motility 

 was lost in a carbonic acid-free medium. In some cases this was the result of the absence of 

 free H-ions but in others it was apparently a specific effect of the absence of carbonic acid. — 

 R. M. Holman. 



2114. Metzner, p. Die Bewegung und Reizbarkeit der bipolar gegeisselten Spirillen. 

 [The movement and stimulus response of spirilla with bipolar flagella.] Jahrb. Wiss. Bot. 59: 

 325-412. 1919. — By observation of the active organisms in the dark field by rhythmic inter- 

 mittent illumination the author has investigated the mechanics of the movement of Spirillum 

 volutans and Spirillum undula under normal conditions and when subjected to chemical and 

 thermal stimulation. These organisms have a single tuft of flagella at each end, consisting 

 of as many as 25 separate flagella united into one rather coarse cord which functions like a 

 single flagellum. This is spiral in form and when active describes rotation figures of various 

 forms, the anterior one a bell opening backward and the posterior one a cup-shaped figure 

 also opening towards the rear. The rotation of this composite flagellum results presumably 

 from the contraction, one after another, of the component flagella. The organism is pro- 

 pelled through the water in a straight path as the result of the rotation imparted to the body 

 of the Spirillum by the activity of the flagella. The rates of the rotation of the two flagella 

 are about the same. In S. volutans it is about forty per second and the rotation rate of the 

 body about thirteen per second. The most common reaction to any stimulus is a backward 

 movement resulting from simultaneous reversal of the direction of rotation of the flagella. 

 The center for the perception of stimulus is apparently at the base of the flagella. Transfer 

 of stimulus from one end to the other of the organism is so rapid that normally reaction by 

 both flagella is practically simultaneous. In case of very weak stimulation or lowered irri- 

 tability a distinct interval may intervene between the reactions, or reaction may be restricted 

 to the end directly stimulated. Moderate temperature increase merely accelerates flagella 

 movement, but further warming checks it, presumably because of exhaustion of raw materials 

 resulting from great increase of normal processes of metabolism. When photodynamically 

 active pigments are present in the surrounding medium flagella activity is checked by light but 

 it may be resumed if the photodynamic action is interrupted in time. Depression of tem- 

 perature causes reversal of the movement of the flagella and continuous diffuse cooling results 

 in rhythmically repeated reactions, as does also a weak homogeneous solution of cocaine or 

 chloroform or any continuous stimulation. — R. M. Holman. 



DIFFUSION, PERMEABILITY 



2115. Gtjerin, p., et Ch. Lormand. Action plasmolysante d'un certain nombre de 

 vapeurs. [Plasmolytic action of certain gases.] Compt. Rend. Acad. Sci. Paris 170: 1598- 

 1601. 1920. — Methyl alcohol is found to act more quickly than ethyl alcohol, and benzylic 



