SEEING BY AID OF THE LENS. 



25 



that the cells of the interior parts may 

 be as readily examined with the micro- 

 scope as those of the epidermis. The 

 hair-like and the glandular appendages 

 and the stomata are preserved in place 

 and in structure, the protoplasmic con- 

 tents alone being contracted toward the 

 center of the cells. 



Liace the petal, the anther, the whole 

 blossom, or a part of a leaf on a slip of 

 glass in a large drop of glycerine. See 

 that the object is completely submerged, 

 and add a large cover-glass. Then boil 

 the glycerine over the lamp-flame until 

 the parts are entirely transparent, or at 

 least translucent, a condition that will 

 arrive in a short time. Do not allow the 

 boiling to be so violent as to disarrange 

 the thin glass ; let it be so gentle that 

 the bubbles will run one by one to the 

 edge of the cover and there break. If 

 the glycerine should become discolored, 

 as will often happen when leaves are 

 under treatment, draw off the liquid, by 

 a wet cloth, and add fresh glycerine, 

 repeating the process and the boiling 

 until the leaf is saturated. The use of 

 glycerine and the saturating of the 

 cells are the secret of the process. The 

 saturation is easily accomplished 

 with petals and with other delicate 

 parts ; with thick and opaque leaves 

 the time needed is longer and the 

 specimen may become only translucent. 

 I have made the thick and opaque leaf 

 of the garden geranium, Pelargonium, 

 so translucent that there was no diffi- 

 culty in examining the hairs on the sur- 

 face, the epidermal cells, the parenchy- 

 ma and vessels, with the cells of the 

 epidermis on the opposite surface. The 

 objects, after this treatment, must be 

 permanently preserved in glycerine. 



Petals and other part" of the flower 

 need no previous preparation. It is well, 

 however, to cut leaves so that there shall 

 be two or more open surfaces to facili- 

 tate the entrance of the glycerine into 

 the substance of the tissue. This is 

 especially necessary when the leaf is 

 thick or very opaque. In some delicate 

 specimens it will not be needed. 



AN INTERESTING ORGANISM FROM THE 

 DITCH. 



(Volvox globator.) 



The partition wall, or dividing line 

 between plants and animals, is narrow ; 



THE WONDERFUL AND INTERESTING 

 VOLVOX. 



in some instances so narrow that it is 

 impossible to decide whether or not a 

 certain specimen is a member of the one 

 or of the other "kingdom," as scien- 

 tific men at one time were in the habit 

 of designating what seemed to be na- 

 ture's way of dividing her creations into 

 Animal, Vegetable or Mineral. Such 

 divisions are even now convenient, pro- 

 vided we do not descend into that mys- 

 terious region where the object is both 

 animal and vegetable, or neither. 



Such living creatures abound wherever 

 water collects, and remains exposed to 

 the air and the sunlight. Every ditch, ev- 

 ery pool, every mill-pond is crowded with 

 these humble creatures, and they puzzle 

 the naturalist who works with the micro- 

 scope, and interest him beyond expres- 

 sion. Some may be nothing more than 

 a drop of living protoplasm, with the ap- 

 pearance and the viscidity of the albu- 

 min of an egg, without a cell wall, with- 

 out organs of progression, without a 

 digestive apparatus, with only a nucleus 

 and a contractile vesicle, yet such crea- 

 tures live, move, digest food, reproduce 

 themselves, die and melt apparently into 

 the surrounding medium. They are 



