REPOKT ON THE EADIOLARIA. Cxlv 



G. The plastic perception of distance of the pseudopodia is shown by the symmetry with which 

 the forms composing the regular skeletal structures {c.j., the ordinary lattice-spheres with regular 

 hexagonal meshes, the radial spines with equidistant branches) are excreted from the exoplasm. 

 Both this form of sensation and the one first mentioned (note F) have hitherto received scarcely 

 any attention, but are deserving of a thorough physiological investigation. 



225. The Cell-Soul (Zellseele). — The common central vital principle, commonly called 

 the " soul," which is considered to be the regulator of all vital functions, appears in the 

 Radiolaria as in other Protista in its simplest form, as the cell-soid. By the continual 

 activity of this central " psyche " all vital functions are maintained in unbroken action, 

 and in uniform correlation. It is also probable that by it the stimulations which the 

 peripheral portions of the cell receive from the outer world are first transmitted into true 

 sensation, and that, on the other hand, the volition, which alone calls forth spontaneous 

 movements, proceeds from it. The central capsule is most likely the sole organ of this 

 cell-soul or central psychic organ, and the active portion may be either the endoplasm or 

 the nucleus, or both. The central capsule may thus (apart from its function as a 

 sporangium, § 215) be regarded as a simple ganglion cell, physiologically comparable to 

 the nervous centre of the higher animals, whilst the exoplasm (sarcomatrix and 

 pseudopodia) are to be compared to the peripheral nervous system and sense organs of 

 the latter. The great simplicity of the functions of the cell-soul which appear in the 

 Eadiolaria, and the intimate connection of their different psychic activities, give to these 

 unicellular Protista a special significance for the comprehension of the monistic elements 

 of a natural psychology. 



Eegarding the theory of the cell-soul as the only psychological theory which is able to explain 

 naturally the true nature of the life of the soul in all organisms as well as in man, see my address 

 on cell-souls and soul-cells (" Zellseelen und Seelenzellen ") in Gesammelte populiire Vortrage aus 

 dem Gebiete der Entwickelungslehre, Heft 1, p. 143; Bonn, 1878. 



(ZOOL. CHALL. EXP. PART XL. — 1887.) ^^ ^ 



