140 THE MICROSCOPE. Sept. 



ience will demonstrate that too little will be more satisfactory 

 than too much. 



Oscillatoria. — These plants are very beautiful objects for the 

 microscope. The}' are frequently found free in water. Often 

 they form a thick green scum on the surface of stagnant water 

 and this scum when gathered will form a thick mat. Having 

 a piece of this mat to examine, with the forceps pinch off ;l 

 piece as big as a pin's head ; transfer to a glass slip ; cover with 

 a drop of water tease out with needles, cover and examine and 

 a beautiful object will be presented. They are conjjiosed of fine 

 microscopic threads containing a blue-green endochrome which 

 is sometimes replaced with red or violet Many genera are 

 enclosed in a hyalene gelatinous sheath. Their motions, 

 whence their name are derived, is interestirg. 



Needle Holders. There is nothing nicer for dissecting 

 needles that the croclr t needle holders which may be procured 

 from any store that deals in fancy goods. Common needles of 

 any suitable size may be inserted and when the needles are 

 broken or useless, new ones may be quickly inserted. These 

 holders are inexpensive and will last a life time, while needles 

 t)ernjanently mounted in handles when broken render the en- 

 tire tool useless. 



QUESTIONS ANSWERED. 



NoTB. — Dr. S. G. Shanks, of Albany, N. V., kindly consents to receive all sorts of ques- 

 tions relating to viicroscopy , ivhether asked by />> o/esswnals or amatnurs. Persons of al^ 

 f ades o/ experience, /rotn the beginner upwu' d, are vc Icome to the benefits of this depar*- 

 t/ient. The questions are numbered/or Juture i e/erence. 



230. ^Mmi are the best books with which to identify microscopic 

 forms v'hich are found in ciquaria and ponds ? 



The best books are Kent's Manual of t}ie Infusoria and Hud- 

 son's Rotit'era or Wheel-Animalcules. 



231. Where can I get information as to the best methods for press- 

 ing and mounting plant specimens and the best sort of a show case for 

 exhibiting them? — L. Stevenson. 



Gray's Lessons and Manual of Botany. Encyclopaedic Brit- 

 anniac — article: Herbarium. Botanical Gazette, Vol. XI, No. 

 (June 6, J 886;, Herbarium number. 



All contain directions for preparing plant specimens. The 

 specimens, mounted on cardboard, are usually kept in tight 

 drawers or on shelves tightly inclosed to keep out dust and 

 insects. 



