138 THE AMERIOAISr MONTHLY [June, 



Bibliography. — This includes principally only the bacteriological 

 papers referred to in this article. 



1. Pasteur. De I'origine des ferments, etc. Comptes Rendus de I'Academie 

 des Sciences, T. L. riS6o), p. Sdg. 



2. Van Tiegheni. Recherches sur la fermentation de I'uree. Ibid., T. LVIII 

 (1864), p. 40. 



3. Pasteur et Joubert. Sur la fermentation de I'urine. Ibid., T. LXXXIII 

 (1876), p. 5- 



4. Miguel, P. Sur un nouveau ferment figure de I'uree. Bulletin de la 

 Societie Chimique de Paris, T. XXXI (1879), p. 391. 



5. Leube, W. Ueber die Ammoniakalische Harn gahrung. Virchow's Archiv. 

 Bd. C. (1885), p. 540. 



6. Fliigge, C. Die Mikroorganismen (1886;, p. 160. 



7. Miquel, P. Ferments de I'uree. Annuaire de L'Observatoire Municipal 

 de Montsouris (1889), p 452. 



8. Ricard, A. De I'asepsie des instruments employes dans le Catheterisme de 

 I'urethre. Gazette des Hospitaux, No. 28 (1890), p. 259. 



9. Musculus. Sur un papier reactifde Puree. Comptes Rendus de I'Academie 

 des Sciences, T. LXXVIII (1874), p. 132. 



. Sur le ferment de I'uree. Ibid., T. LXXXII (1S76), p. 333. 



Common Objects Available for Exhibiting the Power of the 



Microscope. 



By F. BLANCHARD, M. D., 



WASHINGTON, D. C. 



To the amateur microscopist it must often occur to exhibit the power 

 of his instrument to friends who are not familiar with it. On such 

 occasions the selection of unsatisfactory objects is most disappointing. 

 The foot of the common house-fly, although a wonderful structure, has 

 been described so often in juvenile literature that the audience is apt to 

 yawn over an explanation of claws and suction disk. So with the cir- 

 culation of blood in the frog's foot, the rabbit's ear, and the salaman- 

 der's tail. So with the irrational motions of amoebae in Potomac water. 



It is the unpretentious object of this item to enumerate some other 

 readilv obtainable objects for extemporaneous use on such occasions. 

 They require no elaborate preparation and no reagents. 



The feathery dust from the wing of the '' dusty miller" is, perhaps, 

 too commonly used to need mention. The feet, eyes, antenni3e, and 

 wrings of cockroaches, bees, wasps, mosquitoes, and butterflies furnish 

 a great variety of wonder-Inspiring views. 



Often you will be compelled to disappoint some one who expects to 

 see " lots of little bugs" in a drop of well-water, but a drop of slime 

 from the under surface of a lily-pad will fully meet such expectation. 



The tail of the newt still remains the most convenient object for show- 

 ing the circulation of blood. In the same jar where the newts are kept 

 a few sprigs of Chara should be kept growing. The stem of Chara 

 shows cyclosis beautifully. Thin peelings from the bulb of the com- 

 mon onion also show sap circulation well. In cold weather the onion 

 should be kept in a warm place a few hours to quicken the circulation 

 of the sap. 



Cross-sections of common woods make interesting specimens. They 

 can be cut with a keen jack-knife, if one has the "knack." Cornus 

 stolonifera, a shoot \ inch in diameter, makes a good one to begin on, 

 but any soft wood will answer. 



