210 Barrett. — Development and Sexuality of some 
a slender tube which perforated the wall of the enclosing hypha. These 
oval cell-like structures were considered by him as asexual propagative 
bodies of the Achlya. Cienkowski (5), who carefully illustrated and de- 
scribed the development of a similar organism in the swollen hyphae of 
Achlya prolifer a, considered the oval bodies as a third form of sporangia 
of the host. He discovered and figured for the first time what he called 
4 Stachelkugeln spiny spheres or resting spores. He did not observe 
their germination. 
About the same time Alexander Braun (2) reported, after a long 
search, that he had succeeded in finding, in a few hyphae of a characteristic 
form of Saprolegnia on a sick but still living Limneus minutus , the oval 
bodies described by Nageli. Some of these were empty, while others 
were still filled with dark granular protoplasm. He did not observe the 
discharge of the contents of any of these bodies, but from his own ob- 
servations and from those previously made by Nageli, he assumed that 
the structures concerned were not propagative organs, but parasites of the 
host. Braun placed the species in his new genus Chytridium with the 
name C. Saprolegniae , and considered the cell-like structures as zoo- 
sporangia and the motile bodies as zoospores. 
Pringsheim (20), in his work on the sexual organs of the Saprolegni- 
aceae, figures and describes the same or a similar organism. He, how- 
ever, opposed the view of Braun in that he was inclined to interpret the 
oval or elliptical bodies found in the hyphae of Saprolegnia ferax , whose 
oogonia are unaccompanied by male organs, as antheridia, and the zoo- 
spores as motile spermatozoids. He also found accompanying the smooth 
sporangia the 4 Stachelkugeln ’ of Cienkowski. Concerning these he says 
in part (p. 225): 4 Diese Kugeln mit stacheliger Hulle treten entweder 
isoliert auf oder untermischt mit jenen anderen Korpern, welche eine glatte 
Hulle besitzen. Man konnte nun geneigt sein, diese Stachelkugeln als die zu 
den Korpern mit glatter Hulle gehorigen weiblichen Pflanzen zu betrachten, 
&c.’ In his Fig. 15 a, PI. XXIV, he illustrates a spiny resting spore with 
what appears to be an attached empty companion cell. He did not observe 
the germination of the resting spores. 
Not until the appearance of Cornu’s 4 Monographic des Saprolegiees * 
was the question concerning the nature of these organisms again seriously 
considered. In the meantime it rested as left by Pringsheim for an interval 
of some twelve years. Cornu supported the view of A. Braun in considering 
the bodies in question as parasitic organisms. His careful observations did 
not include all stages of the life-history of the organisms, nor did he definitely 
determine experimentally their parasitic nature. He described five species 
parasitic on members of the Saprolegniaceae, three on species of Achlya , one 
on Saprolegnia , and one on Aphanomyces. These he included among the 
Chytridiaceae and in his newly established genus Olpidiopsis. 
