156 Weston .— The Development of 
by de Bary it was again brought to light by von Minden ( 21 ) in Germany, 
and by Coker and Hyman (9) for the first time in the United States. Von 
Minden made no detailed study of the form, but extended de Bary’s 
description through his own observation of material from an inlet of the 
Elbe near Hamburg. By Coker and Hyman, however, the fungus, which 
had been collected from a pool at Chapel Hill, North Carolina, was 
studied for the first time in pure culture. 
In September 1913 a luxuriant growth of Thraustotheca suddenly 
appeared in one of the writer’s cultures which contained algae and silt 
taken from a spring-fed iron watering-trough near Great Barrington, Mass. 
Since the culture, although under observation for a month, had yielded only 
two common species of Achlya , the fungus was probably derived from an 
oospore. 
Methods. 
The fungus was isolated and grown in cooled, covered battery jars. 
A little nutrient material was added every two weeks or so: flies or other 
insects and their larvae or eggs ; bits of earthworms or salamanders; as 
well as the stems, leaf petioles, fruits, and seeds of various plants. By 
occasionally starting fresh cultures to offset the accumulation of injurious 
decomposition products, the fungus was thus maintained without difficulty 
for over eighteen months. 
Pure cultures were obtained as follows: Hyphae bearing young 
sporangia were washed in several changes of sterile water, and allowed to 
remain in a drop on a slide until spores had been formed. This drop was 
then added to a few cubic centimetres of sterile water in an atomizer, 
shaken up, and the resulting suspension of spores sprayed on beef agar in 
large Petri dishes. After the plates had remained in a cool place for 
twenty-four to forty-eight hours, they were examined with a binocular 
microscope, and fragments of the young mycelia that proved to be uncon¬ 
taminated by bacteria were cut out on small chips of agar, and transferred 
to fresh nutrient media. 
Successful use was also made of the method devised by Klebs (18) and 
employed with unessential modifications by subsequent investigators, which 
involves the repeated transference of vegetative mycelium until bacterial 
contamination has been outgrown. In comparison with spraying the spores, 
however, this method proved to be unnecessarily tedious. 
Cultures were also obtained from single spores under microscopic 
observation in the following manner: A few zoospores were introduced 
with a pipette into a drop of water on a slide, and a minute chip of beef 
agar was placed in the centre of the drop. Almost immediately the 
zoospores swam to the agar chip and came to rest here and there upon it. 
Under the microscope single zoospores on minute bits of agar were 
