1912] REY NOLDS—PARASITIZED LEAF TISSUE 373 
chromacetic acid was found to be the most useful killing and fixing 
fluid experimented with. Picric alcohol was less satisfactory, 
because stains of several kinds‘ refuse to affect the tissue when 
preserved in this solution. For the same reason, picronigrosin 
was not very successful. An abundance of material was usually 
kept in the dry condition as herbarium specimens, and some 
was preserved as well in 4 per cent formalin. Paraffin, melting 
at about 52° C., was used for most of the work, though the harder 
grade, melting at 60°, was employed for some of the tough, resistant 
leaf tissues. 
The orseillin-anilin blue method of staining, as outlined by 
STRASBURGER (74a), was used for all of the preliminary work. 
ro 
This combination serves to differentiate the fungus in the host 
tissue, and also to make it easy to distinguish the cell contents. 
The latter stains rather darkly with orseillin, and the host cell 
walls lightly with the anilin blue. The fungous walls stain much 
‘more deeply with the anilin blue. Later in the work, when study- 
ing the nucleus, Haidenhain’s hematoxylin was used, about as 
outlined by CHAMBERLAIN (10). The differentiation thus obtained 
was very satisfactory, since the nucleus held the stain more tena- 
ciously than did the cell walls. Fuchsin also was used to some 
extent. 
About 50 different specimens were preserved, ectinied, and 
examined. Many of these failed to be of value, either because 
of the great destruction of the host tissue by the fungus, or because 
of the absence of distinctive and recognizable cytologic changes. 
The drawings were all made with a camera lucida; and a ;';-inch, 
achromatic oil immersion objective was used for all high mag- 
nifications in all camera drawings. The drawings, with one or 
two exceptions, are of the same magnification, and hence can be 
compared directly with one another. The attempt was made to 
get satisfactory material which would illustrate as great a diversity 
of host plants as well as of fungi as possible. In the following 
pages, therefore, there will be representatives of both monocotyle- 
dons and dicotyledons, and of the latter from several diverse 
families. The Uredineae, the Ustilagineae, the Phycomycetes, 
and the Fungi Imperfecti are all represented. The descriptions 
