84 THE MICROSCOPE. 
extemporary examination, make it a point to find out; it requires 
no genius to do this. If, which is likely, you are unable to make a 
diagnosis, read up in a good text-book containing good illustrations; 
this is dangerous, but you will probably get it right occasionally, 
Examine known tissues and substances, and remember how they 
look. When you get a chance, take a course in a good laboratory, to 
correct you where wrong and confirm you where right. But much 
can be done with perseverance, a text-book, and a little sense. 
If the above course were followed by all the physicians in this 
country, who do not know how to use a microscope, there would be a 
marked change in the prevalence of certain diseases. Bright’s dis- 
ease, for instance, would become less frequent though more fatal, 
and bladder-specialists—if such there be—would wax fat on the 
abundant harvest caused by an increase of cystic catarrhs. 
AcKNOWLEDGMENTS.—From W. H. Haskins, Cleveland, Ohio, 
three slides Salicin and Asparagin crystals. These make beautiful 
polaroscopic objects—From Rev. J. D. King, Edgarton, Mass., 
slides Cellularia, Biscellaria, Bugula, Raby Star, Salutaria, etc.; 
also, samples of King’s well known varnishes. We have already 
mentioned Mr. King’s mounts as being exceedingly beautiful. 
ZO OF) Ga 
THe Porson Apparatus of THE Mosqurro.t—Professor I. Mac- 
loskie has been able to identify the poison-glands and ducts of the 
mosquito, thus complementing the previous work of Dimmock. The 
hypopharynx (Fig. 1) has a delicate tube running through it—the 
whole organ dilating at its base into a trumpet-shaped mouth, which is 
provided with a sac-like reservoir, into which the end of a fine duct 
is inserted. Tracing this duct backwards, Macloskie found that it 
presented the usual character of the salivary ducts in the Diptera, 
but much finer than usual, being less than eight microns in diameter. 
It has the usual chitinous lining, surrounded by the nucleated hypo- 
dermis which secretes it, transversely striated as in trachez (Fig. 3); 
but distinguished from the latter by the comparative smallness and 
constancy of its diameter, and by the absence of ramifications It 
runs back in the lower part of the head, beneath the nervous com- 
* Under this heading will be included all Abstracts relating to the Embryology, 
Histology, etc., of Vertebrates and Invertebrates. 
+ Am. Naturalist, October, 1988, p. 884. 
