McCracken, Egg-laying Apparatus of Silkworm. 267 



NATURE OF THE EXPERIMENTS. 



The following experiments were inaugurated to determine if 

 possible the innervating center of the reproductive apparatus; the 

 extent to which this primary reflex was augmented by removal of 

 the brain; and the degree of correlation between this and other 

 reflex centers. 



After severing the head from the body in the silkworm moth, 

 there is no loss of blood, and the moth shows no signs of incon- 

 venience. The insect rests placidly upon the table. There is no 

 restlessness. No spontaneous movements occur if the sensory 

 surfaces are carefully protected from stimulation. The alluring 

 glands remain retracted beneath the anal plates. A stimulation 

 brought to bear upon the abdomen, however, by pressure with the 

 fingers or rubbing with the pencil, starts a definite and invariable 

 response in the reproductive machinery. All the coordinated 

 reflexes that are involved in the placing of an egg follow. 



This investigation began July i, 1906, when the last of the 

 first generation of the season were maturing. It was continued 

 throughout the greater part of luly and resumed August 30 with 

 a larger number of moths, when the second generation was com- 

 ing to maturity. Practically the same results were obtained in 

 each lot. 



The investigation progressed under fifteen series of observa- 

 tions. The condition of each series was as follows : 



Series i. Moth unmated, not decapitated, not stimulated, hence a normal 

 unmated moth. Table I. 



Series 2. Mated, not decapitated, not stimulated — a normal mated moth. 

 Table II. 



Series 3. Not mated, not decapitated, but stimulated at intervals previous to 

 normal time for ovipositing. 



Series 4. Mated, not decapitated, stimulated previous to normal time for 

 ovipositing. 



Series 5. Not mated, decapitated, not stimulated. 



Series 6. Mated, decapitated, not stimulated. 



Series 7. Not mated, allowed to oviposit a group or so of eggs, than decapi- 

 tated and not stimulated. 



Series 8. Mated, allow^ed to oviposit a group of eggs, then decapitated, not 

 stimulated. 



Series 9. Decapitated, afterward mated, mate removed, moth not stimulated. 



Series 10. Not mated, decapitated, stimulated one to several days after issuing. 

 Table III. 



