Jan. 20, 1923 
Cytological Study 0} Infection 
r 39 
A noteworthy point in connection with this process is the fact that the 
empty haustorium mother cell remains plump. Hundreds of these cells 
are to be found in infected tissue, and while their shape may vary 
greatly according to the available space, they all give the impression of 
having turgor. This would suggest that when the cell contents entered 
the host cell to form the haustorium, at least a thin membrane was left 
behind, lining the cell wall of the mother cell, and that this membrane is 
continuous through the pore with the membrane of the haustorium 
inside the host cell. 
It would be difficult to explain the passage of food from the haustorium 
to the mycelium through the empty cell if the latter does not possess an 
osmotic membrane, for its cell wall alone, if it is of ordinary composition, 
at least, would allow the escape of both the water and the food materials 
contained in it. 
The host cell of Early Baart at this time shows no deleterious effects of 
the fungus. 
In some cases, even in the half-grown haustorium, it is still possible to 
distinguish the two minute nuclei, or at least the nucleoles (PI. 3, A). In 
the full-grown worm-shaped or branched haustoria (B and C), however, 
they can rarely be distinguished, although it is possible that they are 
still present. 
The cell drawn in Plate 3, B (less magnified than tje rest) was located 
near the center of a 6-day-old infection. Cells adjoining it were nearly 
filled with haustoria and surrounded by a felt of hyphae. The cell drawn 
contains two large haustoria, which are intimately associated with the 
living contents of the host cell, being covered with a rich layer of host 
cytoplasm. The infected host cell presents a flourishing appearance and 
may even have more plastids and cytoplasm than an uninfected cell. 
A part of one of the large bundle-sheath cells from a 7-day infection is 
shown in Plate 3, C. The plane of the drawing was near the upper surface 
of the cell and includes some of the cytoplasm lining its upper wall. Three 
very large haustoria and one half-grown one are shown. At the left was 
an intricate tangle of hyphae not included in the drawing. It is not 
uncommon to find 8 or 10 full-grown haustoria in one of these large cells. 
The haustoria possess a delicate limiting membrane inclosing what appears 
to be fungous cytoplasm. There is often, but not always, a denser core. 
Nearly every haustorium, too, possesses one or more rounded clear 
spaces. These may be true vacuoles, or, in the living cell, they may 
have been filled with food material of an oily nature that was dissolved 
out during the preparation of the slide. The necks of these large hau¬ 
storia in Plate 3, C, may have led to hyphae on the upper surface of 
the cell and may have been lost in sectioning. 
Here, as in the younger material, the host cell gives every evidence of 
functioning normally, or even with somewhat heightened activity, and 
host and parasite seem fully congenial. 
KANRED 
The seedlings of Kanred given the same treatment as that described 
for Early Baart showed marked resistance to the local strain of rust. In 
repeated trials the fungus failed to produce flecks large enough to be 
visible to the naked eye. 
Cytological study shows that the spores germinate readily on Kanred 
leaves. The germ tubes make their way directly to the stomata, where 
