McCracken, Egg-laying Apparatus of Silkworm. 283 



The following examples give the time rate of egg placing under 

 the several conditions enumerated above of a single representative 

 moth. 



Moth issued Sept. 21, decapitated Sept. 23, 11.36 a. m. Stimulated immedi- 

 ately. 



Time rate of ovipositing — 9, 16, 26, 13, 12, 10, 8, 7, 10, 12, 13, 15,12, 9, 9. 15 

 eggs. Av. of I per 12 sec. 



Dethoraxed Sept. 23, 4.25 p. m. and stimulated immediately. 



Time rate of ovipositing — 7,17,17,36,15,9,9,21. 8eggs. Av. of i per 16 sec. 



First abdominal ganglion severed 4.30 p. m. and stimulated immediately. 



Time rate or ovipositing — 7, 6, 8, 8, 9, 19, 17, 7, 22, 9, 17, 21, 22, 24, 20, 21, 24, 

 20. 18 eggs. Av. of I per 15 sec. 



Second abdominal ganglion severed, 4.35 p. m. and stimulated immediately. 



Time rate of ovipositing — 8, 8, 11, 8, 14, 12, 11,8, 15, 27, 23, 8, 17, 19, 19. 15 

 eggs. Av. of I per 13 sec. 



Third abdominal ganglion severed, 4.40 p. m. and stimulated immediately. 



Time rate of ovipositing — 9, 5, 7, 16, 34, 19, 6, 31, 15, 13,25,7,24. 13 eggs. 

 Av. of I per 16 sec. 



The coordination of movement in various segments, after each 

 operation, is progressively lost. The ovipositor, throughout, 

 makes the same effort to avoid placing one egg upon another, by 

 moving from side to side. With abdominal ganglia intact, this 

 effort is successful. It becomes, noticeably less and less so as each 

 abdominal ganglion is severed, until when but two remain, mus- 

 cular cooperation of the segments is so far reduced that the com- 

 bined efforts of the last three abdominal segments is not sufficient 

 to pull the body around and the eggs (after the first three or four, 

 which are placed side by side) are piled one upon another. 



The results from the last series of operations show the high 

 degree of independent activity exhibited by the controlling center 

 of the reproductive apparatus, namely the last abdominal gan- 

 glion, and the coordination of the functions of this ganglion with 

 those of the preceding ganglia in the ventral chain. 



Hence the general opinion that "each segment of a segmental 

 animal may be regarded as a simple reflex animal" is only a part 

 of the truth. Bethe found that certain reflexes are located in 

 each thoracic ganglion for the corresponding segment, as already 

 cited. Each thoracic and abdominal ganglion in the silkworm 

 is so organized that the reflexes carried on in the last segment of 

 the abdomen are accompanied by a set of reflexes in other segments 



