560 Theophilus s. Painter, 



considered as a planosome. In such cases the criterion must be 

 behavior. 



Payne (1913) mentions the occurrence of yolk granules in 

 the anaphase and telophase of the division of Redumidae. He 

 states that he considers them as yolk granules because they never 

 divide. However, it seems that we should not make division the 

 criterion by which we judge the character of a body during the 

 maturation period. It is true that division will be a very useful 

 point and decisive when it can be observed, yet this is not the 

 essential characteristic which we should look for. It seems to me, 

 that the main point is, whether or not the body in question is 

 connected with the centrosomes by means of spindle fibers or to 

 some other chromosome. 



Practically, however, it is not always possible to determine 

 whether or not a body is connected to an individual fiber. So we 

 are forced to judge by its ultimate behavior in determining the 

 character of any body which lies in the spindle. If we can follow 

 the course of a body through both divisions and find that it goes 

 to one pole or the other, I think we are safe in saying from 

 the little we know of the mechanism of cell division, that such 

 a body probably has a spindle fiber, though we may not be able 

 to see it. 



It is suggested then, that in determining the character of a 

 body lying in the spindle, we observe three things. First, does the 

 body divide at any time during karyokenesis ? Second, is it connected 

 by means of fibers to either of the centrosomes? Third, does it 

 show any definite distribution to the two daughter cells resulting 

 from the division. Either the first or second point would be decisive 

 when certainly determined. In case, however, these two points 

 were not settled, the third would be sufficient. For if a body is 

 moved to one pole or the other during two successive divisions, we 

 are safe in assuming that it is connected to one or both of the 

 centrosomes and that its movement is not accidental. 



The further question arises, are the small bodies which fill 

 these requirements really chromatic in nature. Wilson (1905) 

 defines a chromosome as follows: "I shall apply the term chromosome 

 to each coherent chromatin mass, whatever its foim, mode of origin, 

 or valence, which as such enters the equatorial plate" (p. 374 

 Study I). It is evident that if a body fulfills the requirements 

 outlined in the preceding paragraph, and gives the chromatin 



