THe Mtcroscopr. 135 
A Pretty SiipE.—A very pretty slide, and one very easily 
made, is the raphides in the sap of the daffodil. Itis only nec- 
essary to squeeze out a drop of sap from the flowering stem on 
to a slide, and on its drying, which may occur spontaneously, or 
be done over a spirit-lamp, we find hundreds of crystals strewn 
over the field of view. With the polariscope they are exceed- 
ingly interesting and brilhant. If we drop over the warmed 
glass a little Canada balsam, we can press on a cover glass. 
SIMULATION OF THE TUBERCULAR BACILLUS BY CRYSTALLINE 
Forms.—The memoirs of A. Celli and ©. Guarnieri give the 
results of a large number of observations on the bacillus de- 
scribed by Koch in the nodules of tuberculosis, andin the sputa 
of consumptive patients, and further call attenton to certain 
crystals found not uncommonly in these sputa, which, both by 
their appearance and by their behavior towards anilin colors, 
imitate the tubercular bacilli. The microscopic differences be- 
tween the two classes of objects are minutely described. 
EXAMINING ALIVE THE HEADs or INSEcTS, SprpeRs, &c.—Mr. 
KE. T. Draper recommends a cone of pasted paper to be made 
rather larger than the specimen, with the apex cut off. <A vig- 
orous spider will soon project its head through the aperture. 
When in this position it should be blocked behind with cotton 
wool slightly wetted. The cone can then be gummed to a slip, 
apex upwards. 
Many insects can be arranged in the same way for the ob- 
servation of facial movements, and such front views admit of 
interesting and extended study, the action of the antenne, 
palpi, and various organs of the mouth may be watched, and 
curious effects produced by the excitation of saccharine or nitrog- 
enous juices, administered from the top of a sable pencil. 
AN InrERESTING ExperriMeNT.—During a recent lecture in 
the Philadelphia Academy of Pharmacy, glass jars were passed 
around containing samples of cultivated disease germs. Pota- 
toes cut in halves had been lightly smeared with a coating of 
substances containing germs. The bacteria were nourished on 
the moist surface of the potato, and presented very interesting 
appearances. Different results were obtained from different 
bacteria, Some of the half potatoes were covered with an or- 
