ON THE MORPHOLOGICAL VALUE OF THE 

 ATTRACTION-SPHERE. 



PART II. 



IN the previous part of this paper I drew attention to 

 the spheres, originally dis- w-- 



covered as structures composed of 

 a large mass of protoplasm (archo- 

 plasm)containinga clear space and 

 a central body (Fig. I.). 



If we now take the centrosome 

 in the figure (c) as a starting-point, 

 it will be seen that each of the two 

 succeeding zones of the sphere is 

 concentrically disposed to the one internally preceding it. 

 Moreover, this concentric zoning does not stop at the external 

 boundary of the archoplasm (a) but is continued beyond it, in 

 the shape of a more or less defined radiation of the general 

 cell contents, which sometimes extends quite out to the 

 periphery (e). 



Such an external differentiated area of the protoplasm 

 has not, however, generally been considered to be a part of 

 the sphere, probably on account of its extremely fugitive 

 and transitory character ; nevertheless as there is little doubt 

 that the radii (e) have sometimes been confounded with the 

 archoplasm, in order to avoid a like confusion, I shall speak 

 of them, when necessary, as the radial envelope of the 

 sphere. 



Through the researches of Flemming and others we 

 have now abundant evidence of the existence of centro- 

 somes and astral radiations in many kinds of tissue, in as 

 many animal forms. But it becomes at once obvious, on 

 instituting a comparison between their figures, or making 

 preparations for oneself, that the usual appearance of the 

 tissue (somatic) spheres is unlike the three-zoned structure 

 originally described. 



For example, in the cells of the amphibian lung and 



