154 THE SAPROLEGNIACEAE 



On ant in spring water. Growth healthy, limited to >2 inch diameter. Many resting 

 sporangia, which were observed to rest for nearly a month. 



On ant in distilled water. As above except growth of about ^ inch in diameter and fewer 

 sporangia. 



On ant in rain water. Exactly as in spring water above. 



On corn meal egg yolk agar. Growth strong, covering dish. An immense number of spor- 

 angia. 



Resting sporangia were taken from No. I of May I, 1913, and put under a cover on slide 

 to test again the emergence under such conditions. In ■'2 hour the spores had begun 

 to emerge in good number. After escaping they would tremble and jerk and turn 

 for several minutes and then swim away. 



At another time the following notes were made: 

 Six minutes after emergence the spores began to move slightly, in 18 minutes there was 



violent motion and in 40 seconds more the spores tore loose and swam away. The 



cilia became visible in living state in 15 minutes after emergence. 

 In .05% haemoglobin. X'egetative growth luxuriant. Sporangia sparingly formed. 



Hyphae seldom branching. 

 In K6H3(P04).:+haemoglobin. Vegetative growth was luxuriant^more than above. 



The hyphae twisted in their course and sent off many lateral branches almost at right 



angles. Sporangia exceedingly abundant. At last all protoplasm of plant seemed 



to be used in forming sporangia. 

 In KNO3 + haemoglobin. Growth was about normal with hyphae not quite so crowded. 



Sporangia were formed in considerable numbers at the tips of the hyphae. Vacuoles 



scattered. 

 In KCl + haemoglobin. Growth was very sparse. Hyphae frequently branched, forming 



sporangia at tips. The protoplasm of the hyphae always exceedingly dense. 

 In MgS04 +haemoglobin. Growth very sparse. Sporangia formed. Hyphae rarely 



branching. 



Experiments to determine the best method of preserving live cul- 

 tures : 



Culture of No. 13 of December 7, 1912, put in aquarium jar with algae in laboratory on 

 February 19, 1913. When tested for life on September 18, i9i7,no growth appeared. 



Culture of No. 13 of December 7, 1912, put in vial on corn meal agar on March 18, 1913. 

 When tested on December i, 1913, it was found to be alive. It is of interest to note 

 that of the sixteen species tested in this way at this time none was found to be alive 

 except Dictyuchus. 



Experiments begun January 15, 1913, show that Dictyuchus will 

 not grow at all on pea-broth-gelatine, on which all species of Saprolegnia 

 grow profusely; nor will Dictyuchus grow on acidified beef agar or on 

 plant decoctions such as prune juice, Baccharis twigs, etc. 



2. Dictyuchus Magnusii Lindst. Synopsis de Saprol., p. 7, pi. i, figs, 

 1-13. 1872.* 



Plate 53 



This has been reported only by Humphrey ('92, p. 132, pi. 20, figs. 

 112-114) from preparations made by Trelease. But Pieters has found 

 *The condensed specific description is on page 18. 



