18091. | _ Entomology. 63 
The pineal eye of the vertebrate may be reduced back to the three- 
layered Arthropod type. There is another more rudimentary pineal 
eye which belongs to the left side, while the previous one connects 
with the right ganglion habenule. The brain of Ammoccetes almost 
compels us to recognize the supracesphageal ganglion of the Crus- 
tacean, etc. 
If any one hopes to find a grain of truth in either of these two 
contradictory theories, which exhibit wonderful displays of mental gym- 
nastics, starting from the Arthropods as from a spring-board, thence 
to take their aérial flight, let such a person read them side by side. 
ENTOMOLOGY.! 
A Review of Some Plum Curculio Literature.—A few 
years hence, when it is finally and definitely settled whether the Plum 
Curculio ( Conotrachelus nenuphar) can be successfully fought on a com- 
mercial scale by spraying with the arsenites, there will be an oppor- 
tunity to write a most curious and instructive chapter in the annals of 
economic entomology. This question has been under discussion by 
entomologists for more than twenty years, and to judge from the latest 
publications concerning it, the end is yet in the distant future. Nearly 
all our economic entomologists have taken part in the discussion, and 
the final record will show a curious mixture of assent and dissent on 
the part of those concerned. 
Before attempting a brief analysis of this record, I desire to quote 
from a letter recently published in Agricultural Science (Vol. IV., p. 
97), in which I made the following statements concerning the philoso- 
phy of spraying with the arsenites, and the conditions necessary 
for a fair test: “ The remedy undoubtedly acts mainly by destroying 
the adult beetles that feed upon the poisoned surface of the fruit and 
foliage, thus preventing, to a greater or less extent, the deposition of 
eggs. It need not necessarily act at all upon the beetles when 
engaged in oviposition, nor upon the larve after hatching. Con- 
sequently a fair test cannot be carried on with a half dozen trees close 
together, three of which are sprayed and the others not. Beetles from 
the unsprayed trees may Oviposit in the fruit of those sprayed, and the 
beetles killed on the sprayed trees will lessen the injury to their checks. 
For the same reason a fair test cannot be carried on in an orchard in 
! Edited by Dr. C. M. Weed, Experiment Station, Columbus, Ohio. 
