No. 466.] STUDIES ON PLANT CELL.— VIII. 699 
view that the cells of the Cyanophycez and also of the Schizo- 
mycetes contain nuclei, taking a position in sharp opposition to 
that of Bütschli ('96). Fischer’s conclusions were based on his 
failure to find that differentiation of the protoplasm within the 
cell demanded by the conception of the central body and the 
activities of this structure during cell division as described by 
other authors. He presented a sharp criticism of the conclu- 
sions based on the reaction of stains in determining the nature 
of protoplasmic structures, criticisms largely directed against the 
investigations of Bütschli. He showed by some ingenious experi- 
ments upon emulsions of albumen fixed on a slide that stain 
reactions were a purely physical phenomenon. Thus the same 
combinations of stains, such as saffranin and gentian violet, may 
be made to give exactly opposite results in differentiating a mix- 
ture of large and small globules of albumen when used in reverse 
order. He attached no importance to the so called affinity of a 
protoplasmic structure for a particular stain and would not accept 
such apparent affinity as evidence of its chemical nature. The 
fact that the central body takes chromatic stains did not seem to 
him important evidence of its nuclear character and he was very 
positive in his belief that the cells of the Cyanophycez do not 
contain nuclei and that the central bodies should not be consid- 
ered the phylogenetic forerunners of such structures. 
This attitude of Fischer towards conclusions based on stain 
reactions was later presented in more elaborate form in his cri- 
tique ('99) on methods of fixing and staining protoplasm and has 
had an important influence on methods of cytological investi- 
gation and interpretation. The stain reaction is now regarded 
as probably merely a physical phenomenon but an effective 
means of differentiating protoplasmic structures. The deter- 
mination of their morphology rests with an understanding of 
their history and behavior in the activities of the cell. Although 
Fischer general criticism of methods of cell research was 
timely and in some instances richly deserved, nevertheless his 
particular conclusions respecting the cell structure of the Cyano- 
phycez and the Schizomycetes have not been sustained by 
investigators who have followed the history of the protoplasmic 
structures in the cells of these organisms. 
