I 
RELATION OK CLIMATK To THK HACKS. 19 
of loni|)(M-;Uin-(^ or w IkM licr the l.'l-vcar vi\cv would main tain il> iionnal 
])iM-ic)(l ill the Noi'th and the IT-ycar race in (he vSouth. Tlic ohjcct of 
tlio ox|)(M-iniont . in otlicr words, was (o dctcnnine wlictlici- the dillci-- 
enco in time of (Unc^lopinent IxMwctMi {]\v two races is r(>all\ <nic of 
climate and temperature only or whether a Wxcd characteristic has 
been ac(|iiire(l, not suhjcu't to imicli, if any, modification w ith clian^in^ 
temj)erature conditions. That the separation was ori^inalU caused 
by diU'ereiices in climate in dillerent parts of the ran^e of the species 
can not be doubted, but th<^ fact that tlie two races often overlaj) in the 
adjoininir territory of tluMr respective ranges would seem to indicate 
that this time })eriod has become in the course of a<i:es a rather 
j)ermanent feature. 
Doctor Jvil(>y's early experiments in this direction were in 1881 
with the 13-year Brood XIX, but the e<i:<xs distributed were in such 
condition that it is doubtful if they hatched, and the effort failed. 
A nmch more elaborate test was instituted in the summer of 1885, 
in connection with the joint appearance that 3^ear of the 13-year 
Brood XXIII, which returned in 1898, and the 17-year Brood X, 
which retiu'ued in 19012. All possible precautions were observed not 
only to collect the eg(2:-bearing twigs at the right moment and to 
distribute them in fresh, healthy condition, but to see also that they 
were i)roperly ])laced under suitable trees and that a record w^as made 
in each instance of the exact locality. Furthermore, most of the 
transfers were kept under observation for a time to see that the eggs 
actually hatched and the larvae entered the soil in their new^ situations. 
The record of these transfers is given in detail in the report of the 
Entomologist, Report of the Department of Agriculture for 1885, 
pages 254-257, and was reproduced in Bulletin 14 as Appendix A. 
The eggs of the 13-year brood were collected in Mississippi between 
July 6 and 17, and distributed to entomologists in Xew York, Iowa, 
Massachusetts, and Maine in eleven lots. The eggs of the 17-year 
Brood X were collected in Indiana, Pennsylvania, and Michigan, 
chiefly in the latter State, between July 6 and 21, and distributed in 
seventeen different lots to correspondents or entomologists in Georgia, 
Mississi])pi. Alabama, and Missouri. The preliminary report on the 
condition of this material is given in the appendix cited of Bulletin 14. 
The only positive record received was from Prof. Eugene A. Smith, 
University of Alabama, w^ho found in 1898 one pupal shell and 
noticed several holes in the ground which answered to the description 
of exit openings made by the Cicada. The pupal shell was sent to me 
and proved to belong to the periodical species. That it comes from 
the eggs planted in LS85 seems probable, from the fact that no brood 
was due in this locality in 1S9S. niid this would seem to indicate that 
the 17-year brood may be greatly abbreviated or reduced to the 
13-year term in a warmer latitude. Part of the eggs sent to Professor 
