NUCLEOLUS 183 



In character the nucleolus is somewhat irregular in shape and may 

 possess one or more vacuoles, in which small granules are 

 occasionally found. The nucleolus shows an affinity for acid 

 dyes, and according to Meyer, Zacharias and others, it is mainly 

 composed of proteinaceous material. In Allium root, according 

 to de Litardiere, the substratum of the nucleolus is made up of some 

 achromatic material which is impregnated with a less resistant 

 chromatic substance or substances. 



Till within recent years, there has alw^ays been considerable 

 divergence of opinion with regard to the function of the nucleolus, 

 but the trend of recent work has shown that it plays an 

 important part at mitosis and supplies chromatin to the developing 

 spireme. 



In his investigations on ferns de Litardiere observed that there 

 was an inverse ratio between the chromaticity of the chromosomes 

 and the volume of the nucleolar mass. He therefore suggested 

 that chromatic material passed out of the chromosomes at 

 telophase and formed the nucleolus, which in turn at telophase 

 passed chromatic material to the chromosomes once more. In a 

 similar manner. Martens discovered that in Paris quadrifoUa the 

 achromatic matrix of the chromosomes showed a very decided 

 chromaticity at late prophase, metaphase and anaphase, and that 

 this chromaticity was lost at telophase. He thought it probable 

 that this w^as due to a transfer of chromatic material from the 

 nucleolus to the matrix of the chromosome during these various 

 stages of mitosis. 



A more elaborate study of the matter was conducted by van 

 Camp on the root meristem of Clivia. Here apparently the 

 reticulum of the nucleus is basophile, whereas the nucleolus is 

 acidophile and has an avidity for iron, and the two are in direct 

 contact. At the inception of prophase the spireme becomes more 

 iron-avid, with simultaneous decrease in the size of the nucleolus. 

 Finally the nucleolus breaks up into small fragments and becomes 

 less iron-avid. With the completion of prophase the nucleolar 

 material has passed entirely to the developing chromosomes. Van 

 Camp claimed that the chromosomes are not simply impregnated 

 by material from the nucleolus, but that the two form a special 



