28 The Scottish Naturalist. 



14th September — The subject of discourse at this fortnightly meeting, was 

 "The Theory of the optical part of the Microscope." 



12th October. — Mr, Dingwall read a paper on the " Hive Bee." Specimens 

 of various species of bees and their combs were shown in illustration of the paper. 



26th October.— Mr. J. Brown, Inland Revenue (late analyst in the Inland Re- 

 venue Laboratory, London), read the first of a series of papers on " Adulteration. " 

 The subject of Mr. Brown's remarks this evening, was the adulteration of starch, 

 and in illustration, about fifty varieties of starch were exhibited under the 

 microscope. These specimens had been mounted by Mr. Brown about six years 

 ago, in diluted glycerine, and had undergone little change since. The author 

 alluded to the well-marked characters afforded by the various varieties of 

 starches, and said that microscopists, instead of almost entirely confining their 

 studies to the examination of diatoms, Arc, might profitably turn their attention 

 to the detection of adulterations. He would therefore be happy to teach the 

 members of the society to detect adulterations, and purposed devoting several 

 evenings to the examination of teas, coffees, mustards, tobacco, &c, procured 

 by the members from the dealers in these articles. 



9th November.— Subject of discussion : " The Laws of refraction." 



23d November.— Mr. Brown read the second of his papers upon adulteration, 

 the subject of which was "Tea, Coffee, Chicory and Cocoa." As tea was often 

 imported in an adulterated state, it was difficult to bring proof of adulteration 

 by persons in this country. Specimens of pure and adulterated teas were 

 shown— one of the latter being a green tea, in which the green colour had been 

 produced by some mineral colouring matter, as was shown by rubbing the 

 damped leaf on white paper. Other examples were exhausted teas re- dried and 

 made up,— these have been sold either alone or else mixed up with good tea. 

 The microscopic characters of coffee were very distinct, and thus it could be 

 easily distinguished from chicory, dandelion root, beet-root, locust beans, etc., 

 with all of which it was sometimes adulterated. Specimens of roasted and un- 

 roasted coffee were exhibited under the microscope, as well as examples of the 

 various substances used to adulterate it. Cocoa was generally sold as a manu- 

 factured article, and purposely adulterated, and little could be done by the 

 members in detecting the adulteration, so long as the public preferred to buy 

 cocoa in the form in which it is commonly sold. Mr. Brown exhibited specimens 

 of theine and caffeine, the alkaloids of tea and coffee, under the polariscope. 



Alloa Society of Natural Science and Archaeology, Sept. 6, 1870.— 

 The Rev. A. S. Matheson, President, in the Chair.— Mr. Borthwick read the 

 first of a series of papers on injuries caused by insects. This paper, which was on 

 "Our garden pests," treated of the ravages caused in gardens by various insects, 

 among which the author mentioned the larvae of Abraxas grossulariata, which 

 during the past season had been very abundant in Alloa, and done much damage 

 in some gardens to the gooseberry and other bushes. Still more destructive had 

 been the larvae of the gooseberry saw-fly. The best means of preventing their 

 ravages is to examine well the leaves in spring, for the eggs of the fly, which are 

 laid along the veins on the underside of the leaf, or, when the caterpillars had 

 appeared, to dust the leaves with hellibore, or water them with a strong decoc- 

 tion of digitalis. Among other insects referred to were various species of beetles, 

 attacking different kinds of fruit trees, the apple moth, the American blight, 

 etc. The paper was illustrated with diagrams. 



