1914] A Study of Dryophanta Erinacet. 17 
rarely found in the central cavities, but generally in the rap- 
idly growing tissue of the gall, where, after emerging, it forms a 
cavity. Again the summer brood oviposit on the young galls 
in July, laying their eggs just beneath the soft outer layer. 
Here on hatching the larva forms a mere depression in the hard 
portion of the gall, the soft outer layer forming the other wall. 
It therefore gives rise to no gall formation. We have here, 
then,’a species of the Cynipide, an inhabitant of a gall, appear- 
ing after the stimulus to abnormal growth has been given, and 
evidently not contributing toit. Its larval Malpighian tubules 
are less developed than those of Dryophanta erinacei. 
The Malpighian Vessels of the Parasites Inhabiting the Gall. 
The Malpighian vessels of a Eurytoma larva, as dissected 
out, are yellowish in color, larger than those of the inquiline, 
and four in number. There are two long, clavate tubules 
drawn to a point at their cephalic ends, and two short ones with 
blunt ends, (Fig. 62, Pl. VIII). These arise at the union of the 
mid and hind-intestine. The long tubules extend cephalad 
slightly ventrad of the mid-intestine beyond the point of union 
of the mid and fore-intestine in the thorax. The cells are 
smaller than those of Dryophanta erinacei, the nuclei more 
compact, and they do not give evidence of a high state of activ- 
ity. Further, it must be remembered that the black eggs of 
these parasites are found only in the central cavities, and never 
in the tissue of the gall. Hence they are in a place where there 
is no demand for gall formation. Again, the galls are well 
developed, and the cavities of fair size before these emerge 
from the egg. Therefore they do not give rise to a chamber, 
as do both the maker and the inquilines. Moreover when 
placed on a glass slide or foreign substance they do not excrete 
a quantity of fluid, as do the larva of Dryophanta erinacei. 
Finally, when they have destroyed the host, the cavity lining 
loses its green, healthy appearance, passing from a yellowish 
brown to a deep brown color. 
Now, considering the habits of the parasites—that they do 
not form a cavity, but occupy one already developed by Dryo- 
phanta erinacei, and feed upon this species—also that the cells 
of their Malpighian vessels do not give evidence of great 
activity, we must conclude that the size of the tubules provides 
no evidence that they produce a gall through their agency. 
