236 UNIVERSITY OF COLORADO STUDIES 



globose, yellow); A. cinerea (Bull.) (sporangia ashen grey, sometimes yellowish- 

 tinted); A. nutans (Bull.) (sporangia cylindrical, ochraceous). 



Family PERICHiENID^ 



Capillitium not elastic. 



(34) Perichsena Fries. Sporangia sessile; wall persistent, thick. P. depressa Libert. 

 Sporangia depressed, polygonal, crowded, brown, dehiscing with a well-defined lid; 

 spores yellow. 



Order MARGARITACEM 



Capillitium of solid threads coiled and hair-like, or straight and attached to the 

 sporangium wall, simple or branching at acute angles (Lister). 



Family MARGARITID^ 



Sporangia dehiscing irregularly. (In Listerellidse dehiscing in lobes.) 



(35) Prototrichia Rostafinski. Threads penicillate, spirally banded. P. flagel- 

 lifera (Berk, and Br.). Yankee Doodle Lake (Bethel). Sporangia globose, sessile, 

 brown or pinkish-brown, shining (Lister). 



In addition to the material already reported, Mr. E. Bethel has 

 collected many specimens in our district, which he intends to record 

 at some future time. 



The Mycetozoa may be regarded as Protozoa adapted to life in 

 air. It has seemed remarkable that so many species should exist 

 in semiarid regions, but it may be that the group arose in such regions, 

 where the need for its peculiar characteristics was greatest. The 

 swarm-cells possess a nucleus and contractile vacuole, and feed on 

 bacteria. They are flagellate, a fact which is against their classi- 

 fication (after Calkins) as Sarcodina. In Ceraiiomyxa the flagellate 

 swarm-cells swim about in clusters, simulating the Mastigophoran 

 genus Anthophysa, except that the latter is stalked. In the Plas- 

 modium stage the slime-moulds are saprozoic. 



The cell-division of the mycetozoa, as described by Lister, is 

 remarkable and raises the question whether they are always to be 

 regarded as colonies of unicellular organisms, or truly multicellular. 

 The ameboid swarm-cells, on emerging from the spore capsules, 

 become flagellate and proceed to feed. Thereupon, like other Pro- 

 tozoa, they increase by division, the nuclei showing the phenomena 

 of karyokinesis. These cells now collect in clusters and unite to 

 form Plasmodia, which are multinucleate masses of protoplasm. 



