558 



VITAL ACTIONS OF THE LOWER FUNGI. 



Influence of 



Of oxygen. 



Of nutrient 

 materials. 



Of light. 



Production of 

 heat. 



considerable expenditure of energy is also necessary for 

 the process of the germination of spores, and this energy 

 is only obtained in the case of most of the fission fungi 

 by the respiration with oxygen, or by a vicarious intense 

 fermentation. The movements of the fission fungi are 

 swimming movements in fluid media, and are generally 

 or always produced by cilia. The mode of movement 

 varies much (seep. 159), and it is usually associated with 

 simultaneous rotation around the long axis. The energy 

 of the movement seems to be dependent especially on the 

 temperature and on the supply of oxygen. 



Too low a temperature, like too great heat, leads to a 

 condition of arrest of movement, and the intermediate 

 temperatures which favour movement most, vary very 

 markedly in the different species of bacteria. Accord- 

 ing to Engelmann's experiments cited above the tension 

 of the oxygen also influences the individual species 

 in very varying degrees, and very slight alterations 

 in it often interfere with locomotion. Pfeffer* has 

 further indicated the presence of suitable soluble nutrient 

 materials as an exciting cause of movement ; where the 

 nutrient material is introduced into the fluid containing 

 the bacteria at one side, the bacteria move towards this 

 part; and if a capillary glass tube containing nutrient 

 solution is placed in the fluid, the bacteria move towards 

 the orifice of the tube and pass into its interior. If the 

 nutrient materials are inadequate these movements do 

 not occur. Whether, finally, light exerts an influence 

 on the mobility of the fission fungi, in a similar manner 

 as it does in the case of certain swarming spores, must 

 remain for the present undecided, because too few species 

 have as yet been tested in this direction.! 



Another form of movement is presented by alterations 

 of shape in the protoplasm without any true locomotion ; 

 the dancing movement of the micrococci may be ascribed 

 to changes of this kind. 



A distinctly noticeable production of heat, similar to 



* Unters. des botan. Jnstituts zu Tubingen, i., 3 Heft, 

 f See Strasburger, Wirkung dcs Lichts und der Wiirme auf Schwiirm- 

 fporen, 1878. Engelmann, Botan, Zeitg., 1882. 



