EXERCISE 27 

 A SAPROPHYTE ; MOLD AS AN EXAMPLE 



Materials. Package of gelatin ; petri dishes or glass sauce dishes 

 with plates of glass for covers. Prepare the gelatin for use as 

 directed on the package and pour enough in each dish to cover the 

 bottom an eighth of an inch in depth. Cover with the glass plates. 

 Allow it to stand until the gelatin has set. 



Directions for work. Transfer a little material from a moldy 

 object to the surface of the gelatin in the dishes. If possible, 

 plant mold from several sources in different dishes. Set the 

 dishes aside for several days or until some growth appears. 

 Some of the dishes should be placed in the dark. Observe from 

 day to day and make a daily memorandum of the facts observed 

 relative to each culture. 



When the mold is well grown make a more careful study, 

 using hand lens or microscope. Determine the following facts 

 regarding the nutrition of the plants : 



Is there one kind of mold or several ? Do the molds possess 

 chlorophyll? Are they able to manufacture food? Do they 

 grow in the dark as well as in the light, and what does this 

 indicate about the source of their food? Do the molds enter 

 the gelatin or have any connection with it which would indicate 

 a possibility of securing food from the gelatin ? Incline one of 

 the dishes and note whether the consistency of the gelatin in 

 the vicinity of the mold patches indicates that the mold is 

 having an effect upon the gelatin. Do these observations prove 

 that the mold feeds upon the gelatin ? 



Write a description of the mold and an account of your 

 observations upon it, with such inferences as you think are 

 justified by the facts observed. 



References 



BERGEN and CALDWELL. Practical Botany, pp. 213-216. 

 BERGEN and CALDWELL. Introduction to Botany, pp. 234-237. 



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