80 Colchicine 



Some materials, such as Spinacid' and Lepidiuni,''' do not show the 

 body. Not all cells of Allium develop the achromatic sphere. There 

 may be some progressi\e relational dcxelopment, or a specific con- 

 centration may be required for producing the achromatic sphere and 

 other similar bodies. That a defniitc progressive stage is followed was 

 carefully shown by the work with neuroblasts. 



Until the final answer is obtained, our jirescnt obser\ations ha\e 

 led to the idea that fibriform materials, that is, substrate making the 

 spindle fibers, are converted into a corpuscular form instead of the 

 usual fibrillar arrangements. Colchicine plays a role in directing the 

 spindle fiber substance into these modifications noticed for many 

 cells. The course of development of the spindle to its disappearance 

 in neuroblasts and the jjrogressive enlargement of the hyaline globule 

 as the spmdle fibers disappear, point to the fact that a spindle 

 material is converted into another form and this form is shown by 

 the hyaline globule. Such a body has definite ojJtical characters, size 

 relationships, and is, in fact, a structine that must be given serious 

 consideration as a changed form of spindle substrate. 



If the globules form at prophase, then karyolymph is suspected to 

 be the original material. When metajjhasic and anaphasic stages are 

 studied, the spindles ha\c been de\eloped and (|uite another A'iew 

 comes into focus. In such cases, colchicine progressively reduces or 

 destroys the spindle, and globules form as spindles disappear. Such 

 globule formation requires a longer lime at metaphase or anaphase 

 than at prophase. Again, both concentration and stage of spindle are 

 important factors in conxerting the spindle into globules-^" (cf. Sub- 

 section 2.4-3) . 



W'hen 25 and 50 X 1^ '' ^^I colchicine solutions are ajjplied during 

 anaphase, the spindle disappears and a hyaline globule forms-^' (Fig. 

 3. ID). The globule occupies a position near one of the poles. The 

 formation of a globule, as the drug acts, leads to a correlation between 

 s|Mndle and globule. Since concentrations determine spindle de- 

 struction, the globular formations are likewise dependent upon con- 

 centration. These facts are clear. 



In agreement with reports on the hyaline globule specifically noted 

 in treated nemoblasts, a similar structure, the achromatic sphere, has 

 characteristics in common with the hyaline globules. Very likely 

 these are similar, just as the spindle fibers of mitoses in cells of plants 

 and animals have certain similar projjerties. Characteristics of the 

 hyaline globule are: (1) it is spherical: (2) diameters vary from 3 to 

 15 microns; (3) rate of formation is related to speed of spindle de- 

 struction; (4) it is opaque, homogeneous, of high \iscosity, not sur- 

 rounded by membrane, and is optically indistinguishable from karyo- 

 lymph or spindle; (5) it tends to lodge at top of cell while chromo- 



