84 2 Scientific News. [October, 



washed again, as before, and set aside to dry, and finally mounted 

 in Canada balsam warmed just sufficiently to spread properly. 

 Corpuscles prepared in this way will be found to be stained red, 

 while the nuclei and leucocytes will be a bluish-green, and will 

 show with great sharpness and brilliancy under the microscope. 



Mounting with black Background.— On principle, I very 

 much dislike to see objects mounted with an irremovable black 

 background. When it is desirable to view objects as opaque, there 

 are so many other ways of doing this. e. g., the diaphragm, or 

 the dark well of the opticians, or a piece of dead-black paper, 

 cloth or velvet placed behind the slide ; it can then still be viewed 

 as a transparent object also. Otherwise it is the mounter saying 

 to the observer : "You shall see my slide as 1 will, and in no 

 other way."— Tuff en West in Journal of the Postal Microscopical 



SCIENTIFIC NEWS. 



— A specimen of the Gila monster, a large lizard, Heloderma 

 horriditm, has been recently added to the Zoological Garden at 

 London, according to Land and Water. This lizard is reported 

 to be poisonous. We remember visiting one which lived loose 

 for a number of months in the front window of an apothecary's 

 shop in Salt Lake City, which showed slight, if any, evidence of 

 ferocity, its keepers not being aware of its reported poisonous 

 qualities. Dr. Irwin, U. S. A., experimented with the H. smpec- 

 tum in Arizona, fifteen years ago, and concluded that it was harm- 

 less. The London individual was tested with a frog, which 

 died after a few voracious bites, and then a guinea pig, which was 

 convulsed and died in three minutes after one bite in the leg; but 

 this might happen if this large lizard was not poisonous, and 

 there is room for more careful experiments as to its venomous 



— Mr. Herbert Spencer, the leading philosopher of England, 

 if not of the world, has been in this country for some weeks, the 

 g .est of Dr. Youmans, the editor of the Popular Science Monthly. 

 xvlr. Spencer, it is understood, will not lecture while in the United 

 States, as he is traveling for his health. While few will probably 

 have the pleasure of meeting this great thinker and organizer of 

 new lines of thought which have already revolutionized social as 

 well as physical science, it is a great pleasure to have him among 

 us, and we feel sure that every one will earnestly hope for his full 

 restoration to health and former capacity for work. 



— Professor R. Ellsworth Call has met with good success in 

 his collecting tour in the Gulf States, having obtained a large 

 number of the Strepomatidce, a group of shells which he intends 

 to monograph. He designs not merely to systematize the group, 

 but to give their anatomy, development if possible, distribution, 

 habits, &c, &c. He has already eight-tenths of all the nominal 



