156 THE AMERICAN MONTHLY [July, 



insects and plants in cabinet collections. Twenty-five grains of the 

 powder stirred up in two quarts of water were sufficient to kill young 

 cotton worms. The tincture has been recommended by Jaeger as a 

 protective against the bites and annoyance of insects. He declares that 

 in traveling and hunting in Asia and other tropical countries one single 

 application of the tincture over the hands, face, and beard always gave 

 him at least twelve hours immunity from the attacks of all kinds of in- 

 sects, even white ants, which are the greatest plague of those regions. 

 According to Professor Maisch, it is capable of producing a vesicular 

 eruption like that of poison ivy. 



Pyrethrum flowers, grown in and around Berlin, have been experi- 

 mented upon by Dr. Unger, with the view of determining their insec- 

 ticidal powers. The Pyrethrum roseum-wsiS found to be quite efficient, 

 killing in three-quarters of an hour ; but the variety known as Cau- 

 casian was not so well adapted for use as an insect powder ; the insects 

 were stupefied somewhat by it, but rarely killed. P. carneum was 

 totally inefficient. Dr. Unger thinks that the first-named variety may 

 be cultivated with profit in and around Berlin. 



The demand for the powder having much increased of late, it is said 

 to be adulterated with the leaves and stems of the plant, hellebore, tur- 

 meric and other adulterants. Some writers claim that hellebore is de- 

 structive to insects, but Marpman made a practical test of the value of 

 hellebore as an insecticide. Placing some true insect powder and some 

 flies under one tumbler and imprisoning an equal number of flies under 

 another glass with powdered hellebore, he found that while in a very 

 short time the insects in contact with pyrethrum were paralyzed ; after 

 the lapse of twenty-four hours no change could be noted in those in 

 contact with hellebore. I made a microscopical examination of seven 

 specimens of insect powder ; two of the specimens were obtained from 

 grocery stores. The method for examination was to remove the color 

 of the powder by means of alcohol, then removing the alcohol and add- 

 ing a little oil of cloves, and mounting in Canada balsam. I used a 

 one-fifth inch objective in examining the various specimens, and found 

 one specimen to contain starch ; by means of polariscope I found this to 

 be potato starch. Two of the specimens contained pollen, while in the 

 other five specimens I was unable to find any. Some of the specimens 

 -contained portions of the leaves and stems of the plant. I also examined 

 for hellebore and curcuma, but found none in any of the specimens. 

 Powdered hellebore and curcuma, as found in the drug stores, is a 

 much coarser powder than insect powder. — Meyer Bros., Druggist. 



Diatomaceous Earth at Montgomery, Ala. — Mr. K. M. Cun- 

 ningham, of Mobile, Ala., discovered on May 8, 1891, a bed of infu- 

 sorial (diatomaceous) earth at Montgomery, Alabama. The deposit 

 outcrops in a ravine, and has a thickness of from five to twenty feet. 

 Mr. Cunningham states that vast beds of siliceous pebbles underlie 

 and overlie the stratum. Evidences of plant remains are occasionally 

 found in the stratum, but are friable and very much compressed. This 

 discovery will prove of interest as affording a contrast to the fresh-water 

 fossil deposits of the New England States. As far as we are aware, 

 this is the first mention of a fresh-water fossil deposit occurring in the 

 Southern States. 



