Abstract
In unfixed tissues of the nucleolar wall of L. campestris, the nucleoli are occasionally bipartite or U-shaped, When bipartite, their appearance may be similar to that of heterochromatic elements visible in smear preparations.
When treated with acetic acid, the atypical nucleoli react similarly to normal nucleoli and unlike the chromosomal substance. The atypical nucleoli are usually not stained by the custamary aceto-carmine technique but can be stained intensely following Rattenbury's formol modification.
Atypical nucleoli are much more frequent in nuclei with two nucleoli than would be expected if their occurrence were not related to the binucleolate condition. The idea is offered that the atypical nucleoli are formed in part by a failure of the usual fusions of material collected by the organizers.
A further observation of vacuoles in unfixed nucleoli is noted.
