362 University of California Publications in Zoology [Vol. is 



to receive stimuli from external sources and to convey impulses to the 

 motor organs. There is thus established a fibrillar connection between 

 the sensory structure of the lip and the motor parts of the organism. 

 Such a relationship strongly suggests the idea brought out in an 

 earlier paragraph, namely, that we are dealing here with a system of 

 such a primitive type that the motor and sensory functions are not 

 separated but that they are both in the same fibers. 



Thus it is seen that Euplotes patella possesses a structure well 

 adapted for relating the organism to its environment, and to coordinate 

 the movements of feeding and locomotion in such a way as to bring 

 the animal under the most suitable circumstances for its existence. 



Evidence of Neural Function. — The question at once arises, why 

 attribute a nervous function to this system? Evidence favoring such 

 a conclusion comes from a study of both living and stained specimens, 

 so that it is not necessary to depend wholly upon one source of evidence 

 as a basis for such ideas. 



1. Chemical Reactions. — The first point favoring the idea that the 

 neuromotor apparatus is of a truly nervous character comes from 

 animals stained with Mallory's connective-tissue stain. In animals 

 treated with this combination of dyes, different organs take different 

 colors. It is characteristic in metazoan tissues treated by these colors 

 for different tissues to stain differently, as for example nerve fibers 

 have an affinity for acid fuchsin and are thus dyed red while nuclei 

 stain orange red, and cytoplasm in general becomes light pink. Such 

 a differential stain may be used to give a clue to the function of 

 organelles in some of the more complex of the so-called unicellular 

 organisms. At least we may assume that structures having a similar 

 staining reaction have the same or related chemical composition and 

 in these so-called simple organisms probably the same general function. 



This is one of the reasons for basing our conclusion that the struc- 

 tures described as comprising a neuromotor apparatus are probably 

 nervous in their function. All of the fibers, granules and motorium 

 stain bright red when treated with Mallory's stain, w^hile the other 

 structures take other colors. The only other organ which constantly 

 stains with acid fuchsin is the micronucleus, but in this the color is 

 not the same as in the fibers but has more of the orange G mixed with 

 the red. 



2. ]\Iorphological relationships. — Were we to base our notion of the 

 function of the neuromotor apparatus solely on the staining reactions 

 our conclusions might well be subject to severe criticism. However 



