142 ■ Ulothricaceae and Chaetophoraceae 



easily be made to give reasonable assurance of preservation of the 

 specimen. While these preparations are not always as well fixed 

 as those made by more elaborate methods, they are very satis- 

 factory for systematic purposes. They even have certain advan- 

 tages and on the whole are perhaps more useful than more care- 

 fully prepared mounts ; the brief subjection to the osmic acid often 

 renders the nuclear and chromatophore characters sufficiently 

 clear, and the natural appearance of the cell-wall is better pre- 

 served than in material subjected to longer fixation. Furthermore 

 branched forms can be arranged in a much more life-like manner, 

 and delicate' setae are less likely to be lost, than when specimens 

 are passed through many washings. 



For preservation in bulk, dilute formalin often gives fair or 

 good results. A better medium, because of its more truly fixative 

 power is Pfeiffer's solution of equal volumes of formol, pyrolig- 

 neous acid and methyl alcohol. This is convenient for field use, 

 as only a small quantity is required, and specimens may be fixed 

 and preserved for months in it. At any convenient time the ma- 

 terial may be removed and, after washing, preserved for staining in 

 glycerine or alcohol. Specimens may even be mounted on the 

 slide in chromic alum directly from this fixative, and they will 

 show a good degree of differentiation. 



Distribution 



No very extended account of the distribution of these plants 

 can be given at present. The printed lists in the various local 

 catalogues are too meagre to be of much value, even if the deter- 

 minations could be considered reliable. Mr. Wolle's collections, 

 though comprehending specimens from widely separated regions, 

 furnish no very definite contribution to our knowledge of distribu- 

 tion, for a large part of his labels state only the habitat and not the 

 locality in which the specimens were collected. It is to be pre- 

 sumed that most such specimens were collected in the vicinity of 

 Bethlehem, Pa. No general request for specimens from botanists 

 of different sections has been made, because of the difficulty of 

 positive determination of dried specimens. 



Our personal collections have been made largely in Greater 

 New York and its immediate vicinity, extending to the palisade 



