CCXXVl 



5. Tubes of this kind, blackened on the inside, are very convenient in 

 studying color sensations. Using two such tubes, look through one with 

 the right eye — say, at red ; through the other with the left eye at green 

 paper, illuminated by the direct solar ray. The color sensations fade with 

 mavelous quickness. Transferring both eyes to either color — say, red — 

 the eye fatigued by green sees the red greatly intensified, the effect being 

 rendered the more striking by the simultaneous impressions received by the 

 two eyes. Experiments in the combination of color sensations will readily 

 suggest themselves. 



The editor of the Scientific American has written something quite simi- 

 lar to some parts of this communication (Oct. 14), but a comparison of it 

 with my communication to Nature will show that I am not the borrower. 



Mr. Shepard Cabann^ was elected an Associate Member. . 



November 20, 1876. 



Vice-President Todd in the chair. 

 Ten members present. 



The Corresponding Secretary read the following letter from 

 Mr. Riley, dated Manhattan, Kansas, Nov. nth : 



Parasites on Eggs of Caloptenus spretus. 



A large proportion of the locust eggs throughout the country are being 

 destroyed by parasites, predacious insects, and other enemies. Some are 

 addled from excessive moisture, while a few have prematurely hatched ; 

 but the hopes that some people are building on these facts are not war- 

 ranted. If nine-tenths of the eggs deposited over large parts of Kansas, 

 Iowa, Nebraska, Minnesota, etc., should from one cause and another fail 

 to hatch next spring, there will still be young locusts enough to devour 

 every green thing, and the people should prepare for the worst. With a 

 mild, alternately freezing and thawing winter, the destruction of the eggs 

 may be such that the injury will be comparatively slight next spring, but 

 this will not do to count on. The people throughout this section (Kan- 

 sas) are in good spirits, and are organizing the better to meet the threat- 

 ened evil. Let the worst come that can, they are in much better condition 

 to meet the injury than they were in 1874-75. Corn is plentiful and cheap. 



I have discovered four new enemies of the locust eggs. One — the most 

 common and efficient — is a new species of Anthomyia, which I shall de- 

 scribe as the calopteni ; the second is the common flesh fly, Sarcofhaga 

 carnaria : the third is the larva of some Hymenopteron belonging doubt- 

 less to the Ichneumon flies, and not yet reared to the perfect state ; and the 

 fourth is the larva of a ground beetle (Carabtdce) of the genus Harpalus. 



The Secretary read another communication from Mr. Riley, 

 on " Locust Flights East of the Mississippi." He had examined 



