76 THE PIvANT WORLD 



Our Teachers' Department. 



Edited by Professor Francis E. IvLoyd, 



Teachers College, Columbia University, New York City, 



A SIMPLE METHOD OF STUDYING ROOTS. 



A VERY satisfactory little arrangement for the observational and experi- 

 mental study of roots has been used by me. It is made of a piece of glass, 

 some sphagnum moss, a sheet of strong paper — which should be oiled 

 or paraffined, the latter preferably — and a bit of string. Lay a good lot of 

 the broken-up and cleaned moss on the glass, to which it is to be firmly 

 tied by means of the paper and the string in such a manner as to leave 

 the glass face uncovered, and one edge of the package, so to speak, open. 

 Seeds may now be planted in the moss at any desired depth, against the 

 glass. By placing the whole device in various positions, the corres- 

 ponding behavior of the roots and shoots may be observed. All the roots 

 can be made to grow against the glass by tipping it forward. Laying 

 the glass on its face, the roots will wander here and there, seeking to 

 penetrate the glass. By alternately tipping to the right and left (assum- 

 ing the observer to be facing the glass) at intervals of one to three days, 

 a wav>' tap root may be produced which will produce lateral roots only 

 on the outer, and not on the concave, faces of the curves. If a piece 

 of blue litmus paper is laid on the glass before the moss is adjusted, 

 wherever the roots come into contact with it the acid reaction will be 

 shown. 



This arrangement, it will be seen, replaces to some extent, at least, 

 the ordinary root cage or box, which is of necessity more bulky and less 

 adaptable for experimentation. Any desired position may be maintained 

 by leaning it against a vertical surface, as a wall or the inside of a desk, 

 provided that the glass used is small enough. Or a stand may be con- 

 structed of heavy wire by bending it after the manner of a photograph 

 frame stand. Another advantage lies in the ease with which any number 

 of these may be had for the use of large classes, thus making it possible 

 for each pupil to conduct his own experiments. Any suitable size may 

 be chosen, uniformity in this regard being desirable in the case of large 

 classes. 



DETERMINATION OF OXYGEN OBTAINED FROM PLANTS. 



Teachers of elementary botany who have attempted the experiment 

 outlined in almost every text-book for the collection and determination of 

 oxygen excreted by water plants have probably all experienced consid- 

 erable diSiculty, if not failure, in carrying it out. They will therefore 

 be glad to learn that a simple and effective method for this experiment 



