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1914] A Study of Dryophanta Erinacet. 
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(Walsh); Eurytoma studiosa (Say); Eurytoma auriceps (Walsh) 
Ormyrus ventricosus (Ashmead); Syntomaspis sp.; Tetras- 
tichus sp.; Synergus erinacei (Bass.) 
A. The Chalcids are primarily parasitic on Dryophanta 
erinacei, and secondarily on each other. 
B. The inquiline, Synergus erinacei, is parasitic on the 
entire life of the gall, mining from cavity to cavity and devour- 
ing the larve they contain. 
C. Eurytoma studiosa and Eurytoma auriceps, and Syn- 
ergus erinacei have two broods. The spring brood appearing 
June tenth to fourteenth, and the summer brood appearing 
from July twenty-fourth to August first. 
D. The percentage of parasites, not including the internal 
parasites, is at least sixty per cent. 
3. The Malpighian vessels of Dryophanta erinacei secrete 
a fluid which stimulates the plant to produce the gall. This is 
shown by the following: 
A. The character of the Malpighian vessels of the sexual 
and agamic forms of Dryophanta erinacei—their size, cellular 
structure, and exceptional glandular activity. 
B. The character and effect of the secretion poured forth 
by the Malpighian vessels during gall formation. 
C. The ultimate decline and ceasing of marked activity 
of the tubules when the gall has matured. 
D. The increase in the size of the cells of the Malpighian 
vessels coincident with the development of the gall, and their 
decrease in size when the demand upon them is withdrawn. 
E. A comparison of the Malpighian vessels of Dryophanta 
erinacei with those of the parasites and the inquilines found in 
the gall, and particularly the lack of any abnormal secreting 
activity in the latter. 
F. A study of the Malpighian vessels of Holcaspis globu- 
lus, and Dryophanta polita, both of which correspond in their 
action, development, and degeneration to those of Dryophanta 
erinacel. 
G. A comparative study of the Malpighian vessels of Dryo- 
phanta erinacei with those of Nematus pomum, Trypeta 
solidaginis, and Cecidomyia strobiloides shows that all the 
latter, though gall producers, possess tubules of normal type, 
which do not pour forth an abundant secretion during gall 
development, nor when in contact with foreign substances. 
