ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 771 



typhoid bacillus, Spirillum cholerse asiaticse, &c., were also investigated 

 with positive results. On the other hand, the colourless Flagellate, 

 Astasia proteus and CJiilomonas paramecium were found to be absolutely 

 non-chemotactic, as also were the green Flagellata and all the Infusoria 

 investigated (12) ; the latter indeed seemed to possess no chemotactio 

 susceptibility whatever, oxygen excepted. 



The organisms examined were found to be positively or negatively 

 chemotactic according to the nature of the stimulant material, and 

 sensitive in different degrees. A given substance may act upon one 

 organism, but not upon another, e. g. dextrin excites B. termo to an 

 extraordinary degree, but not Spirillum. 



Among inorganic bodies the salts of potassium in general, and 

 among the organic bodies peptones particularly act as lures, the carbo- 

 hydrates less, whilst glycerin has no effect. 



Negative chemotaxis or dispersion of the organisms is usually pro- 

 duced by alcohol, acid and alkaline reactions, and by a too great 

 concentration of the stimulant material. The nutritive value of any 

 substance, and its stimulant capacity, stand in no direct relation ; glycerin, 

 for instance, possesses no chemotactic action, although an excellent 

 nutritive material for many bacteria. How extremely sensitive organisms 

 are to certain substances is shown by the fact that B. termo is attracted 

 by even a • 001 per cent, peptone solution. 



The paper contains numerous remarks on the convenient application 

 of chemotaxis for catching certain organisms, which if correct may be 

 found of service in shortening the time taken in obtaining pure 

 cultivations. 



M. J. Massart * has repeated, and to a large extent confirmed, 

 Dr. Pfeffer's observations. The Flagellata, Tetramitrus rostratus and 

 CMlomonas paramecium, stated by Pfeffer to be non-chemotactic, he finds, 

 on the other hand, to be very sensitive. 



(4) Clieinical Cliang-es (including Respiration and Fermsntation"). 



Changes of Substance and Force connected with Respiration.f — 

 Dr. H. Eodewald continues his observations on the chemical and 

 mechanical changes which accompany the process of respiration of plants. 



CO 

 The average value of the fraction -pr-^ he finds to be 1-061 ; for 1 ccm. 



O2 

 of CO2 there is given off 4 • 37 cal., and for 1 ccm. of O2 4 • 46 cal. 



Formation of Starch from various substances. | — By immersing 

 filaments of Spirogyra in the substances in question, Herr T. Bokorny 

 finds that plants have the power of producing starch from various sub- 

 stances of the nature of alcohols, as well as from glucoses, viz. from 

 methylol (probably in consequence of its splitting up readily into formic 

 aldehyd and methyl alcohol), glycol, glycerin, and mannite. All these 

 substances agree in being compounds of hydroxyl OH with carbon and 

 hydrogen. 



* CE. Soc. R. Bot. Belg., 1888, pp. 88-98. 



t Pringsheim's Jalirb. f. Wiss. Bot., xix. (1888) pp. 221-91 (1 pi.). Cf. this 

 Journal, ante, p. 455. 



% Ber. Deutsch. Bot. Gesell., vi. (1888) pp. 116-20. 



