SAPROLEGNIA 27 



Distribution: Chapel Hill, Massachusetts, Pennsylvania, Alabama, 

 Louisiana. Also listed without notes liy Kauffman as found by Pieters 

 in Michigan ('15, p. 195). 



For points of difference between this and S. anisospora, which is 

 nearest, see that species. From S. delica it is distinguished by the far 

 less numerous and larger oogonia, smaller and more numerous eggs, 

 diclinous anthcridia only, and the quickly disappearing antheridial 

 branches; and from S. ferax by the numerous antheridia and the slightly 

 pitted oogonia. For other illustrations see Minden ('12), fig. le on p. 

 520; Tiesenhausen ('12), figs. 4 and 5. 



This is one of our commonest species, but is often difficult to deter- 

 mine with certainty because of the infrequency of sexual reproduction 

 at room temperature. While the oogonia are not rare under ordinary 

 conditions they are not nearly so abundantly formed as in other species, 

 and sometimes many cultures will be made before they are found. How- 

 ever, sexual reproduction can be greatly increased by lower temperature, 

 and can nearly always be obtained in an ice box. 



Trow states ('95) that fertilization always occurs in this species 

 (as 5. dioica deB.) and in practically the same way as in 5. mixta, which 

 see for some detail. 



To find if the plant is really dioecious cultures were made from a 

 single spore from No. 10 of October 25, 191 2, and from this the following 

 five cultures were made: 



Two cuhures on antsweremadeabout January 26th. One was put on the window sill outside, 

 the other kept in the laboratory. By February loth the one outside had formed 23 

 typical oogonia that were crowded with numerous antheridia of the usual distant 

 origin. The oogonia were formed close in to the ant, as commonly, and the antheridial 

 branches were very delicate, but in the unusual cold they did not disappear so soon. 

 All the 23 oogonia were measured and they were found to average 62.98iX in diameter. 

 The largest was 86.95^1, the smallest 40.7yL. The largest had about 20 eggs, the 

 smallest 2 eggs. The eggs in this culture ran very regular, about 24^. in diameter. 

 .\fter staying out for about three weeks without a freeze this culture was frozen for 

 about 36 hours. Taken in and tried it was found to be totally dead (unless vitality 

 remained in the eggs: they would not sprout at the time). The numerous gemmae 

 were all collapsed and dead. The culture inside also formed oogonia of usual character; 

 a few were cylindrical. .Antheridia very numerous and thickly enveloping the oogonia. 

 Antheridial branches very ephemeral. As usual the oogonia were sparse, only about 

 50 in the culture. Some were very small and with only one egg, others quite large. 



On an ant in watch glass with water from .'Arboretum spring. Many sporangia, about 6 

 oogonia; no gemmae. 



On an ant in watch glass with rain water. Exactly like the above in appearance and result, 

 except that there were no oogonia. New ant put in and again only sporangia. 



On an ant in watch glass with distilled water. No oogonia. 



