THE MIGRATION THEORY. 41 







Iii Georgia the worms were widespread a natural result from the 

 great invasion of the previous year. In Early they were seen July 1, 

 and had done some little damage before picking season. In Schley they 

 appeared too late to do harm, and in Muscogee were seen upon bottom 

 lands only. Some damage was done in Dodge, Wilkes, Jackson, and 

 several other counties, and Murray suffered a loss of 40 per cent. In 

 South Carolina they were seen in a few localities, some crops being dam- 

 aged in Beaufort and Eichlaud Counties. Pamlico County, Xorth Caro- 

 lina, reported " the worm," but it is difficult to say whether the cotton- 

 worm or the boll- worm is meant. 



In the latter part of this year Mr. A. R. Grote read a paper before 

 the Hartford meeting of the American Association for the Advance- 

 ment of Science, in which lie announced that, after long study and 

 personal observation, he had come to the conclusion that " the cotton 

 worm may be considered not a denizen, but a visitant brought by va- 

 rious causes to breed in a strange region, and that it naturally dies out 

 with ns in the cotton belt, unable to suit itself as yet to the altered 

 economy of its food plant and to contend with the changes of our 

 seasons." 



This is, of course, nothing more than a repetition of the migration 

 theory, as we may call it, which Thomas Affleck, Dr. Gorham, and Dr. Bur- 

 nett had successively and independently put forth as the result of their 

 study into the natural history of this insect, and it is a very interesting 

 fact, that a man of Mr. Crete's scientific ability should have arrived at 

 the same result through independent observation and reasoning. It is 

 also a curious and interesting fact that one of the arguments by which 

 Dr. Gorham reached this theory, and one of the main arguments by 

 which Mr. Grote arrived at the same point, started from bases as diam- 

 etrically opposed to each other as two bases could well be j namely, the 

 existence and the non-existence of parasites'. Dr. Gorham visits the 

 cotton fields after the last brood of worms has spun up, and, finding 

 every chrysalis that he tries to breed parasitized, jumps to the conclu- 

 sion that all of the last brood are parasitized. The natural question 

 now is, where will they come from next year ? and the natural conclu- 

 sion, from some exterior country where the cotton plant is perennial and 

 parasites do not exist. Mr. Grote's observations, on the other hand, 

 failed to show him any parasite, although he acknowledged that such 

 might exist ; and the absence of such peculiar parasites argued that the 

 worm was not a regular denizen, and could be accounted for only by the 

 s] .reading of the insect as a moth. Since Mr. Grote again put the old 

 theory into shape, it has been much discussed by those interested, its 

 principal opponent being Professor Riley. Yet that the latter plainly 

 acklowledged the strength of Mr. Grote's arguments is seen in the cot- 

 ton-worm circular of 1878. (See introduction.) A special chapter will 

 be devoted to this subject. 



In March, 18o4, some six mouths before Mr. Grote read his Hartford 



