OBSERVATIONS ON AN ACHLYA LACKING SEXUAL 
REPRODUCTION 
Wm. H. Weston 
The following paper embodies the results of the writer's investi- 
gation of a Saprolegniaceous fungus which shows the zoospore pro- 
duction characteristic of the genus Achlya, but which lacks sexual 
reproduction. The resistant function exercised in most species of 
Achlya by the sexually produced spores is apparently assumed, in 
the form to be described, by large, heavy-walled spores of non-sexual 
origin, and sharply defined morphological characteristics. Structures 
of a similar nature have been recorded in other Saprolegniaceae ; but 
this form is unique in that its reproduction is limited to the zoosporan- 
gia and to these structures which are of a particularly distinct type. 
In contradistinction to the zoospores, these bodies are resistant to 
unfavorable conditions. It seems advisable, therefore, to avoid the 
implications of the names ''conidia," "chlamydospores," ''gemmae," 
"Sporangienanlage," "resting sporangia," or "resting spores," gen- 
erally used for these structures; and to employ simply the term 
"resistant spores." 
The writer realizes only too well the incompleteness of this study; 
and regrets that the untimely destruction of stock cultures has pre- 
vented the further physiological and cytological investigations which 
had been planned. These results are presented for publication in the 
hope that they may prove of interest to those working in the same 
field. 
MATERIAL AND METHODS 
The fungus appeared on dead flies dropped into a culture containing 
sediment and algae from a stone watering trough at Waverly, Mass. 
For over two years gross cultures of the fungus were successfully 
maintained in battery jars cooled in running water, and covered with 
glass to exclude the dust. 
Pure cultures were obtained by the following methods. 
I. A young sporangium was washed repeatedly in sterile water, 
and allowed to discharge zoospores in a drop of sterile water on a 
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