ANCYLISTALES 119 



B. Mature thallus more or less branched, transversely septate, but 

 not markedly constricted at the septa; component cells often 

 differing considerably in size and form. 



3. Lagenidium, p. 122 



ir. Swarmspores not formed; asexual cells of thallus germinating by germ 

 tubes; thallus sometimes considerably branched. 



4. Ancylistes, p. 124 



1. Achlyogeton Schenk (1859). 



In this genus the mature thallus is an unbranched elongate 

 tube, septate at regular intervals, and constricted so deeply at 

 the septa that a row of broadly ellipsoidal, slightly connected 

 cells results. Each cell functions as a sporangium, the swarm- 

 spores passing through an exit tube to the exterior of the host 

 cell. At the rupture of the tip of the tube the swarmspores pass 

 out and encyst individually at the mouth, forming a globose 

 aggregation of tiny spheres as in Achlya. After encystment they 

 swim away. They were figured as uniciliate by Schenk, but 



Fig. 43. — Achlyogeton entophytum Schenk, in thread of Cladophora. Chain of 

 segments functioning as sporangia. (After Schenk 1859.) 



inasmuch as the swarmspores in all the other accepted members 

 of the order (see Resticularia) are bicihate the point requires 

 verification. No indication of sexuahty has been obtained. 

 Martin (1927) figures thick-walled resting spores which he found 

 associated with the sporangia but fails to demonstrate their true 

 nature. Oospore-like resting spores, such as occur in other 

 genera of the family, are unknown. 



The genus was based on a single species, A. entophytum Schenk 

 (Fig. 43), found in cells of Cladophora. It was recently redis- 

 covered by iMartin (1927) in Iowa. Another species found in 

 the bodies of Anguillulidae, and referred to this genus by Sorokin 

 as A. rosiratum is imperfectly known, and may be more properly 

 included in or near Myzocytium vermicolum (Zopf) Fischer, 

 found in the same host. 



