262 



and the specimens examined represent the collections of three years from 

 this vicinity. Many species were from the campus and the shade trees 

 along the streets of the city. 



Great care was taken in collecting. The exact place of its occurrence, 

 the date and other important data were preserved with the material. The 

 best specimens of each species were mounted for future reference, while 

 the remaining material was preserved for study. On each collecting trip 

 every specimen of slime mould was talien and subsequently identified to 

 insure thoroughness in the local work. This was necessary, as many spe- 

 cies could be determined only by extended study and comparison with 

 other material. Several species that appear exactly alike to the naked 

 eye vary greatly in minute structure. 



Besides this, very careful mounts were made, both in balsam and 

 glycerine jelly, from fresh specimens. The spores were removed from 

 those mounted in balsam, in order to show eapillitium structures; others 

 to show spore markings were mounted in jelly, containing a small amount 

 of potassium hydrate to swell the spores. Careful measurements of spores 

 were kept and records preserved of their color en masse and under the 

 microscope. Fresh material was always used for color records, as the 

 spores change with age, and the entire sporangium with its spores changes 

 color several times during the process of fruiting. The following record 

 kept of S. maxima will illustrate this: 



June 25, 7 p. m., Plasmodium, pearly white. 



June 26, 6 a. m., fruited (still wet), purple black. 



■Tune 26, 10 a. m., brownish, dark. 



June 27, 3:30 p. m., lighter brown. 



July 20, spores shed, purple brown, pale. 



This specimen grew on an old charred stump convenient to the labora- 

 tory, and we examined it several times each day to note any changas of 

 color. Records of color variation of species of other genera also show 

 this striking change of color during and after fruiting. 



For determination of species, Macbride's North American Slime Moulds 

 were used, while Lister's Mycetozoa was used for reference and com- 

 parison. 



Before the presentation of the conclusions based upon a study of spor- 

 angium and spore structure, the following miscellaneous notes and obsei'- 

 vations may be of some interest: 



