Reed—Infection Experiment's ivith Mildew. 533 
observed on infected cotyledons of the squash, pumpkin and 
cucumber. They were formed on plants which were under 
observation by students in plant pathology. These plant.} were 
inoculated on October 12th, and infection was first observed 
October 18th. Twenty days later the perithecia were first ob¬ 
served. A study of these showed that the mildew is Erysiphe 
cichoracearum DC. 
The methods used in the experiments described below were 
essentially the same as I have described for the grass mildew 
in a previous paper (22). The plants were grown in three-to 
five-inch pots. Usually they were inoculated after one or 
more foliage leaves had developed and expanded; in other cases 
only the cotyledons were inoculated, the first leaf being still 
small and not yet expanded/ 
The parts inoculated were first moistened with water, and 
then conidia were applied by means of a scalpel. Control 
plants were kept in nearly every experiment. The plants were 
then placed under a bell-jar; in this way a moist atmosphere 
was secured. The bell-jar was usually removed a few days 
after inoculation. Infection was regularly first observed from 
three to five days after inoculation, when minute fiecks of my¬ 
celium could be seen. A few days later conidia were formed 
abundantly. 
The experiments were extended to a considerable number of 
varieties of squashes, pumpkins, cucumbers and gourds, repre¬ 
senting the standard sorts in common cultivation. Every pos¬ 
sible cross infection was tested in order to determine whether 
the mildew on anjy one cucurbit would pass over + o any other 
member of the family. The results of these experiments are 
given in the following tables. 
In classifying these different varieties of cucurbits I have 
followed Gray’s “Field, Forest and Garden Botany,” and also 
Bailey’s “Encyclopedia of Horticulture.” In some cases I am 
uncertain to what morphological species a given variety be¬ 
longs. Some of these varieties are probably hybrids between 
species of Cucurbit a. 
The seed was obtained from J. M. Thorbum & Co., Hew 
York, and Henry A. Dreer, Philadelphia. 
