56 



ial masses are hard and brittle and they may be broken into 

 small pieces without danger of damage. When afforded proper 



conditions of moisture and temperature living plasmodia will 

 emerge from sclerotia or sclerotial fragments. 



In preparing material for class use the writer places pieces of 

 sclerotia on the surface of one per cent, non-nutrient agar which 

 has been poured into petri dishes. At room temperature Plas- 

 modia em^erge from the sclerotia within a few hours (fig. 1). 

 The lids of the petri dishes may be removed for periods of several 

 minutes without risk of excessive drying and the plasmodia can 

 be examined and observed both with and without a microscope. 



As observed with the unaided eye plasmodia can be seen to 

 change their position on the substrata and their conformation 

 more or less continuously. Thus it is seen that they are endowed 

 with powers of locomotion and exhibit a creeping movement. 

 As viewed with a microscope, they are seen to consist of granular 

 protoplasm containing numerous inclusions and vacuoles. This 

 protoplasm exhibits a systemic circulation but the protoplasmic 

 movement is most noticeable in the thicker channels and veins 

 of the plasmodial sheet or reticulum (fig. 2). Through these 

 veins and channels the protoplasm streams in a very rapid cur- 

 rent which gradually comes to a pause in the space of a short 

 time, and then immediately reverses its course. A rhythmic 

 backward and forward flow is thus maintained, but it can be 

 observed to flow longer in one direction than in the other. The 

 flowing movement is generally of longest duration in the direc- 

 tion in which the plasmodium is creeping. 



New College, Columbla. University 

 New York, N. Y. 



