THE FUNCTION OF CONSCIOUSNESS. 501 



I do not know, but he had not probably been brought 

 up among matches, and his act was in any case not 

 reflex. 



As an illustration of the simplest of movements, 

 and their physical conditions, I cite those of the Myx- 

 omycetes, from Stahl.^ 



"The movement of Myxomycetes is influenced by: 



"I. Moisture (Hydrotropism): In their young 

 stages they wander from the parts of the substratum 

 (i. e. of the deposit on which they are creeping), which 

 are gradually drying up, toward those which continue 

 moist longer ; ' it is even possible, by bringing moist 

 bodies into the proximity of any ramifications, to cause 

 the production of pseudopodia, which elevate them- 

 selves from the substratum, and soon come into con- 

 tact with the moist object, so as to enable the whole 

 mass of the plasmodium to migrate on to it. ' On the 

 entrance of the plasmodia into the fructifying condi- 

 tion, positive hydrotropism gives place to negative ; 

 the myxomycete quits the moist substratum and creeps 

 upwards on to the surface of dry objects. 



"2. Unequal distribution of warmth in the sub- 

 stratum, and 



"3. Unequal supplies of oxygen also cause loco- 

 motion in the myxomycete. 



"4. Chemical substances soluble in water have a 

 similar action. Contact of the plasmodia on one side 

 with solutions of common salt, saltpetre, or carbonate 

 of potash, cause them to withdraw from the danger- 

 ous spot, while infusion of tan, or a dilute solution 

 of sugar, produces a flow of the protoplasm and ulti- 



lE. Stahl, "Zur Biologie der Myxomyceten," Botan. Zeitung, 1884, No. 

 10-12. Abstract in SitzungsbericM der Jenaischen Geselhchaft fUr Medizin 

 tend Naturwissenscha/t, 1883, Sitzung vom 16. November. 



