MICROSCOPY. 707 
pool, calls attention to the fact that about fifteen grains of 
camphor added to the paraffin in an ordinary sized lamp about an 
hour before using, will greatly increase the brilliancy of the light. 
Mountinc SmALL OpJects IN Batsam.— A correspondent in the 
“English Mechanic and World of Science,” who has been troubled 
by the balsam washing away from the centre of the slide small 
objects, such as starch grains and diatoms, advises that the balsam 
be placed on the slide in the form of a ring around the object, so 
as to run in upon it from all sides and not drift it away. A 
better contrivance is to wet the object and allow it to dry upon 
the slide, after which it will not easily be misplaced. A trace of 
gum arabic may be added to the water if, as will seldom be the 
case, it should be found necessary. 
Bone Dust 1x Soar.— If any kind of soap seems irritating to 
the skin, particularly the cheaper kinds of ‘* Old Brown Windsor,” 
try the microscope for the detection of fine particles of ground 
bone which have not been separated from the fat of which the soap 
was made. 
Tue Fresh Warer Porree. — Mr. James Fullagar gossips 
pleasantly about the Hydra vulgaris in “ Science Gossip.” He 
as no difficulty in multiplying his specimens by cutting up the 
= animals; though the parts do not lead an equally favored life, 
_ for the head-part proceeds to eat immediately, while the stalk is. 
obliged to wait patiently several hours, fasting, until a new head 
and tentacles are developed. The polypes contracted and dissolved 
into a confused mass of granules in December. None could be 
found during the winter, but very small ones appeared in the 
Spring, and still tater these assumed a large size and began to mul- 
tiply by budding. The earliest that appeared, much smaller than 
those produced by budding, he believed to be produced from eggs, 
though their origin escaped him, as it had escaped previous 
Observers. 
_ Repropvuctioy or Sroxcrs.— In a memoir on two New Sponges, 
ete., in the Annals and Mag. of Nat. Hist., Mr. H. J. Carter re- 
marks that he last year confirmed Prof. H. James Clark's discovery 
of a “collar” round the cilium of the sponge animal, which must 
_how be regarded as the animal of the sponge, as much as the polype 
: is regarded as the animal of the coral. 
