1890.1 MICB(3SCOPICAL JOtlKNAL. 16:^ 



EDITORIAL. 



Meeting of the American Society. — Notice is sent out that if 50 

 members will get certificates that they have paid full fare going to De- 

 troit, it will be possible to secure return tickets at ^ regular fare. This 

 " if" implies doubt, and as a matter of fact in several past years there 

 have not been 50 such members. Additionally, reduced hotel rates 

 have been expected and not realized on some occasions. Unless the 

 Society can control these two features the attendance will suffer, and in- 

 deed it had better hold its meetings in conjunction with the American 

 Association for the Advancement of vScience, which always does get 

 return rates and reduced hotel fares. 



^Valte^ H. Bulloch. — We are glad to announce the early removal 

 of anotlier friend to Washington. This time it is the accomplished 

 optician of Chicago, Mr. W. H. Bulloch, who comes here in order to 

 accept a position in the Coast Survey. If his friends each give him one 

 or two more orders at Chicago before the end of this month they will 

 probably receive attention and perhaps some fine bargains in view of 

 his closing business there. We shall be delighted to have him in 

 Washington, and he may expect a cordial reception. 



BOYS' DEPARTMENT. 



Microscopical Examination of Starch. — The following para- 

 graphs embody all the essential parts of an enticing article by our friend 

 Dr. W. H. Sylvester, of Natick, Mass., in 71ie Observer : 



Starch is composed of minute white granules or cells which difter 

 in size or shape in the difibrent varieties of tuberous roots and plants. 

 Starch may be detected by adding a small quantity of a solution of iodine 

 to a mixture suspected of containing it. All starch grains without ex- 

 ception turn blue in the presence of iodine. Starch furnishes beautiful 

 objects for observation and study. It is one of the easiest things looked 

 at by beginners. The several varieties can be readily obtained, and 

 there is not a cheap compound microscope that will not distinguish the 

 grains. 



Cut a bit of potato fine in cold water, let it stand half an hour, then 

 turn ofi'the water, and in a short time a sediment will be thrown down, 

 which is the true potato starch. Place a drop of the sediment on a glass 

 slide, cover with thin glass and look at it with a power of one-fourth to 

 one-half inch. A much lower power will distinguish the grains. Small 

 clam-shell-shaped bodies will be seen under careful focussing man-ied 

 almost exactly like the surface of a clam shell, the most of the lines 

 seeming to ratliate from a dark spot in the centre called the hilum. In 

 some kinds, as in arrow^root, the hilum looks very much like a crack in 

 the centre, reminding one exactly of the crack in tlie centre of a potato 

 that has grown too rapidly. 



Difierent varieties of starch may be distinguished by measuring the 

 grains with a micrometer, although many cells of each should be meas 

 ured and the average taken as the size varies,. For example, many of 

 the larger grains of arrowroot exceed in size the smaller grains of potato 

 starch, but the average size of the grains of potato starch is much larger 



