58 MINNESOTA BOTANICAL STUDIES. 



Thus, some were polyhedral, some oval, some spherical and 

 some irregular in form. It also varied in size. The nu- 

 cleolus stained much more deeply than the nucleus and was 

 spherical in shape. Radiating in all directions from the nu- 

 cleus are the lighter staining strands of protoplasm which, 

 terminating in the pyrenoids of the chlorophyll bands, suspend 

 the nucleus in the cell. 



Zygnema species. — A mixture of ammonia and borax carmine 

 gave the best results in staining in this form. Various stages 

 in nuclear division were clearly brought out. PL XIV., Fig. 

 7, shows two daughter nuclei just after the formation of the 

 cell plate. The nucleus is an elongated, oblong, bean-shaped 

 body situated between the two chloroplastids. The nucleolus is 

 generally situated in one end of the nucleus and is spherical in 

 shape. Dahlia was tried but it stained all the contents of the 

 cell without bringing out the nucleus. 



Hormiscia zonata (Web. and Mohr) Aresch. — The method 

 of staining was the same as above. The nuclei are somewhat 

 spherical in shape, and occupy different positions in different 

 cells. They lie within the chloroplastid, either at the center or 

 near the wall. 



Microspore! species. — In addition ^to the first method, double 

 staining was tried, the material being first stained with anilin 

 safranin and then with gentian violet. This proved to be no 

 more satisfactory than the first method. Stained with haema- 

 toxylin the nucleolus was brought out much more clearly than 

 in either of the other ways. The method used is as follows : 



Chromic acid, 33 hours. 



Water, 22 " 



Hematoxylin, 4 " 



The material was then washed in water acidulated with HC1, 

 then placed in a solution of glycerine, and mounted in glycerine 

 jelly. The nucleus in Microspore! is irregularly spherical or 

 oblong in shape. It usually occupies the center of the cell. 



Ccenocyte Staining. 



Hydrodictyon rettculatum (Linn.) Lagerh. — The stain used 



was a mixture of ammonia and borax carmine. The nuclei do 



not seem to be distributed uniformly throughout the coenocyte, 



but most of them occupy a layer or cylinder just within the cell 



