Crystal Cyst Formation in Parenchymatous Tissue . 171 
pathological cell. For example, the nucleolar proteins might change into 
secretion products. 
According to Haecker’s (16) theory of the structure of the nucleus, the 
nucleolus is merely a splitting off or intermediate product due to the change 
in material. These products are removed from the nuclear content as a sort 
of secretion during the rest period at the beginning of mitosis, and may be 
either in combined or uncombined form. Haecker therefore concludes : 
‘ Inasmuch as the need for living substance increases when division becomes 
more active, as a necessary consequence there follows the production 
of living substance in the form of large and—because of the small size 
of the nucleus—compact nucleoli.’ The opinion of Haecker that the nucleoli 
are living substances is, however, contradictory to his assumption that they 
are cleavage products or secretions. 
Other important evidences of the secretory-like character of the nucleolus 
are that the nucleolar substance increases considerably as soon as the 
nucleus is affected by the abnormal concentration of acidity in the hyper¬ 
trophied cyst cell, and also the appearance of the death and dissolution 
of the nucleus, which is very striking as soon as the nucleolus has filled the 
entire volume of the nucleus. 
Although the abnormal increase in size of the nucleolus gives us some 
information as to the end of its existence, the opinion is that its contents 
are nothing but an assimilation or secretion product. This also finds sup¬ 
port in the abnormal size of the nucleolus in the primary endosperm nucleus, 
which I have occasionally observed in the embryo-sac of Gunnera shortly 
before division (see 40, Plate IV, Fig. 28 ). But inasmuch as we have to 
deal in the latter with a normal or regular phenomenon and the division 
of the nucleus directly follows the increase in size of the nucleolus, one 
should make a distinction between the two. 
After this discussion of the role of the nucleolus in the hypertrophied 
cyst nucleus we may accept the theory of Haecker with the proviso that 
the nucleolus is not regarded in pathological cases as an intermediate but 
as an end product of the metabolism ; his theory deals exclusively with an 
excretion of the nucleolar substance during the division of the nucleus under 
normal conditions. 
Other cytologists, like Carlier (2) and Heidenhain (17), believe 
that the nucleolus is nothing more than an organized excretion product 
of nuclear metabolism, and that this substance should be separated from the 
chromatin. 
Wilson (60) agrees with Haecker that the nucleoli may be regarded as 
a transformation product of the chromatin or as a chemical cleavage product 
or secretion. Wilson says : ‘ It seems not improbable that nucleoli are 
tributary to the same general process, perhaps serving as storehouses 
of material formed incidentally to the general nuclear activity, but not 
