WITH NOTES ON OTHER SPECIES. 133 



Dictyuchus monosporus Leitgeb ("69). 



111.: Leitgeb, '69, PI. XXII, Figs. 1-12; XXIII, 1-8. 



i^ot yet known in America. Resembles the last species closely, but has smaller 

 oogonia and short, coiled antheridial branches. 



Dictyuchus pplyspwus Lindst. ('72). 



III.: Lindstedt, '72, PI. II, Figs. 1-3 ; III, 1-7. 



Distinguished by its large, globular, many-spored oogonia and its antheridial 

 branches of androgynous origin, from all other described species of the genus. ISTot 

 seen in America. 



In one of my cultures of Aph. scaher there appeared hyphse and sporangia of a 

 species of Dictyuchus. A vigorous growth of it was readily obtained on fresh flies 

 and kept up in successive generations for several months. In ordinary cultures in 

 glass vessels, the sporangia are freely and normally produced both in basipetal series 

 and by cymose branching. In cultures on slides in a moist chamber, one often sees 

 sporangia lobed and forked in quite irregular fashion, like those figured by Leitgeb 

 ('69) for D. monosporus. The plant seems slenderer and more delicate than 

 D. Magnusii of Prof. Trelease's preparation, and is very probably not that species. 

 It does not appear that either the basipetal development of sporangia or their forked 

 shape can be regarded as of any specific value. In spite of repeated efforts to induce 

 their development, the sexual organs of this plant have uniformly failed to appear, 

 so that it is quite impossible to say what species it represents. After the formation 

 of sporangia has begun to decline, the main hyphse of a plant commonly send out 

 a mass of fine lateral branches, themselves much branched and interlacing, which 

 give to the whole culture a densely woolly appearance. These threads probably 

 correspond to those which bear the sexual organs in D. monosporus, but, although 

 readily kept alive and healthy for a long time, they remain persistently sterile. 

 Gradually the later generations of the plant showed signs of degeneracy, and ulti- 

 mately refused to yield normal plants. 



Two or three cultures from various sources have produced a plant with slender 

 hyphse and sporangia of the Dictyuchus type, except that they contain only a single 

 file of zoospores, being cylindrical and little larger than the hyphse. It is this form 

 whose sporangium is shown in Fig. 16. I have never been able to find its sexual 

 organs, and specific determination is, therefore, impossible. 



