The Reproduction of Ahnfeltia plicata. 15 
of the end-cell has a large nucleolus or central body, glob- 
ular or usually somewhat depressed. It is homogeneous in 
structure and stains intensely or, with a high degree of dif- 
ferentiation, more feebly by hematoxylin after HEIDENHAIN. 
The material was fixed in FLEMMING’s weaker solution or 
after NAWASHIN’s method, but equally good results were 
obtained with material preserved many years ago in strong 
alcohol by Dr. HENNING E. PETERSEN. In some cases, in 
specimens preserved in FLEMMING’s solution or in alcohol, 
Fig. 12. Same material as fig. 11. Four end-cells from the same section 
showing nucleus and chromatophores, the latter apparently partly fusing 
together. 1800 : 1. 
the chromatophores could not be observed, but usually 
they were very distinct in a number of 2 or 4 or rarely 
more. The shape of the chromatophores is very variable, 
ribbon-shaped, rod-shaped, linear with attenuated ends, 
sometimes very long and curved or spirally twisted. Their 
staining power after HEIDENHAIN’S method is considerable, 
often greater than that of the nucleolus, The most remark- 
able feature in the young monosporangia is the fact that 
the chromatophores are not unfrequently found lying in 
pairs close together along their long axis as shown in 
several of the figures. When two chromatophores are exactly 
of the same length and are placed very close together, they 
