220 THE AMERICAN MONTHLY [July, 



is covered with a thin coat of soft paraffine or '' paraffine 

 gum," and of which " chewing gum "* is made. This enables 

 one to cut ribbons of any desired length, since the softer paraf- 

 fine at the edges of the successive sections stick them together 

 by their margins as fast as they are cut. 



The ribbons may be allowed to fall upon a slip of paper, 

 which may be drawn out, as fast as the sections are cut, 

 from under the bed-plate of the instrument, beneath which 

 there is a space left for this purpose between the three toes 

 or tripod upon which the whole apparatus rests. The edge of 

 the knife also remains in the same plane, no matter at what 

 angle the cutting edge is placed with reference to the direction 

 in which the block to be cut is moved, just as in the best forms 

 of the sledge microtome. 



Complete instrument, including knife and walnut case, $25. 



BACTERIOLOGY. 



Tuberculosis. — A Royal Commission appointed five years 

 ago by the British Parliament has concluded extensive re- 

 searches and reports : 



" We have obtained ample evidence that food derived from 

 tuberculous animals can produce tuberculosis in healthy ani- 

 mals. The proportion of animals contracting tuberculosis after 

 experimental use of such food is different in one and another 

 class of animals ; both carnivora and herbivora are susceptible 

 and the pro'portion in pigs is high. In the absence of direct ex- 

 periments on human subjects we infer that man also can ac- 

 quire tuberculosis by feeding upon materials derived from tu- 

 berculous food animals. The actual amount of tuberculous 

 disease among certain classes of food animals is so large as to 

 afford to man frequent occasions for contracting the disease 

 through his food. As to the proportion of tuberculosis acquired 

 by man through his food or through other means we can form 



* Chewing gum may be rendered available for this purpose if it is melted 

 at a temperature somewhat above boiliug, when the sugar which it contains 

 will separate as caramel, leaving the pure paraffine gum, which may be 

 drained off and used as directed, if the manipulator should find it difficult 

 to get the paraffine gum of commerce. 



