MOSSES WITH A HAND-LENS 3 



Two blank slides, two rubber bands, a pair of fine-pointed 

 forceps, and a small vial of water carried in the pocket into the 

 field will enable one to mount slides on the spot and will often 

 eave the trouble of carrying home useless material or, what is 

 worse yet, leaving a good thing behind because it is not recog- 

 nized. The rubber bands are to slip over the two slides and keep 

 them in place when objects are mounted between them. 



To use a hand-lens with the best results the object or slide 

 should be held with the thumb and fore finger of the left hand, 

 and the lens with the right hand. Then by resting the right 

 hand on the left the lens can be focussed without difficulty. It is 

 usually best to let the thumb of the right hand lie on that of the 

 left. If the hands do not touch it is very difficult to keep them 

 steady enough to keep a high power hand-lens in focus. 



The only parts for the study of which the dissecting micro- 

 scope is absolutely necessary are the antheridia and archegonia. 

 These organs are readily found in acrocarpous mosses if 

 not too badly decomposed by age, and after a little practice one 

 will have little difficulty in distinguishing them with a high 

 power lens. In the pleurocarpous mosses they are often difficult 

 to find. The best plan is to soak the plant thoroughly and place 

 it on a large piece of glass, over white paper, and dissect off all 

 promising buds. These are to be dissected separately in a drop 

 of clean water on a slide, but they are so small and so often 

 shrunken or partially decomposed as to make their recognition 

 difficult. 



In counting peristome teeth it is well to remember that the 

 teeth are always in multiples of four, 4, 8, 16, 32, or 64, so that if 

 a number more than one of these numbers is found one may 

 know that the entire number is not less than the next higher. 



Every one intending to study mosses will find a collection of 

 dried specimens invaluable, and a collection is more easily made 

 and cared for than with any other group of plants. The only 

 reason for pressing specimens of mosses is that they may be 

 stored satisfactorily in the herbarium. Each species has a dis- 

 tinctive look when naturally dried in situ, and the pressure should 

 not be great enough to obliterate this. Note the difference be- 

 tween plants of Hedwigia dried under pressure and dried in the 

 open, and you will easily see how important proper drying is for 

 the student. My own practice is to place the mosses in an or- 

 dinary plant-press and press with medium pressure for twenty- 



