December 9 , 1892 .] 
SCIENCE. 
several improvements in apparatus and methods of experiment 
have already been made, one on the time of action and the fatigue 
of monocular accommodation, another on the rapidity of move- 
ment of the arm under the conditions present while writing, 
anothefton the reaction-time to tones as dependent on pitch, in- 
tensity, duration, etc. 
The ample accommodations furnished by the fifteen rooms, the 
three months of energetic preparation dining the summer, the 
high scientific stand taken in regard to research, the wise pat- 
ronage of Professor Ladd and the enthusiasm of the young inves- 
tigators lead us to hope that the first.! ear will see us with a recog- 
nized standing, second only to Wundt's laboratory at Leipzig. 
Nevertheless, tbere'are many difficulties to be overcome; the 
work of instruction really requires as full an equipment as a ] hy- 
sical laboratory; moreover, research is the most expensive kind 
of work, thus putting a great strain on the appropriation. It 
would be a very great help if some one or more friends would 
undertake to support or aid some one of the researches, setting any 
desired amount as the limit beyond which the expenses are to be 
paid by the laboratory. We have already received considerable 
aid in our work: Professor Ladd h^s given the laboratory his 
valuable collection of charts and models and a microscope; a 
friend has donated $75 for electric forks required in one of the 
researches; the B. F. Sturtevant Co. has -sent a rotary blower; 
the Electric Gas Lighting Co. of Boston has sent a dozen Samson 
batteries; the Aluminium Brass and Bronze Co. of Bridgeport has 
made us a dozen discs twelve inches in diameter; the Boston 
Woven Hose and Rubber Co. has furnished soma, of their cross- 
stitched rubber belting ; E. B. Meyrowitz has sent a set of test- 
cards, etc. More of such help would be thankfully received ; at 
present we need a i horse-power motor, a spark coil, etc. Pos- 
sibly the day is not far distant when an endowment will be made 
for a separate building and a full equipment of apparatus. 
HYBRIDISM EXEMPLIFIED IN THE GENUS COLAPTES. 
BY SAMUEL N._RHOADS, ACADEMY OF NATURAL SCIENCES, PHILA- 
DELPHIA. 
Perhaps the most widespread and persistent tendency to 
hybridism that exists among the higher vertebrates to-day is to 
be found in this American genus of woodpeckers. The birds re- 
sponsible for such a slate of affairs are well known in their re- 
spective habitats as flickers, the eastern species being named the 
yellow-shafted flicker ( Colaptes auratvs), and its western con- 
gener, the red- shafted flicker (Colaptes cafer) by naturalists. 
It early became known to explorers in the upper Missouri and 
Yellowstone regions of this country that where the habitats of 
these red- and yellow- shafted birds adjoin there often occurred 
individuals partaking the characters of both species. Audubon 
described in the appendix to his “North American Birds,” a 
flicker from this region, with the yellow shafts and red nape of 
auratus combined with the red mustaches of cafer, as a distinct 
species, naming it Pious ayresii; but as more specimens were se- 
cured it became evident that these intermediate birds were not 
constant in character and their numbers were too great to be ex- 
plained by any other theory than that they were the offspring of 
distinct species and were hybrids. Professor Baird enunciated 
this idea in 1858, classing for convenience all these nondescripts 
under the distinctive name of Co’aptes hybridus , and asserting 
that their existence could be satisfactorily accounted for in no 
other way. The amount of material on which he based his 
theory, however, was small enough to warrant other theories, 
Mr. J. A. Allen attributing the existence of so-called “ hybridus ” 
to the “ action of environment in accordance with certain laws 
of geographic variation,” and later Mr. Ridgway suggested they 
were ‘ 1 remnants of a generalized form from which two incipient 
species have been differentiated.” Dr. Coues, in 1884, thought 
the mixed birds might constitute “ perhaps a hybrid and perhaps 
a transitional form,” while Hargitt, in the British Museum Cata- 
logue, makes the intermediates a race with the nominal status of 
a species under the Audubonian name of ayresii , admitting them 
to have been originally the result of a mixed union, showing pos- 
sibly a “ sign of reversion to remote ancestral plumage.” 
325 
Last year (1891) Mr. J. A. Allen made the relationships of the 
whole genus the subject of an exhaustive study. The results of 
his examination are given in full in Yol. IV. of the Bulletin of 
the New York Museum of Natural History and being inaccessible 
to the genera] reader may be briefly summed as follows: — 
1. Mixed birds show no stages of geographic variation com- 
parable with those connecting species and sub-species. In the 
latter the transition is gradual, symmetrical, and correlated with 
change of environment, but in Colaptes the intergradation is ir- 
regular, often asymmetrical and without such correlation. 
2. Very unlike birds have been found to breed together; di- 
verse offspring being reared in the same nest by parents indif- 
ferently exhibiting normal or abnormal characters irrespective of 
sex. But so far typical cafer and auratus have not been found 
paired together. 
3. On either side of the boundary of one thousand miles, along 
which their habitats adjoin, the influence of one species upon the 
other fades imperceptibly’ eastward and westward till it disap- 
pears. 
4. The main area of hybrid distribution covers a belt of country 
two hundred miles wide and reaching nortb-westwardly from the 
Gulf-coast of Texas through Colorado, Wyoming, Montana, 
northern Idaho and Washington and the southern half of British 
Columbia to the Pacific, extending from southern Alaska to the 
mouth of the Columbia River. South and west of this the habi- 
tat of true cafer reaches from the Columbia to Tehuantepec, 
while north and east of it pure auratus ranges, over an area four 
times as great, from Florida to Hudson’s Bay and from Labrador 
to Behring Sea. 
5. Formerly, collections from certain parts of the far West, 
notably California and Nevada, were wanting in hybrids, but 
now they have become so common in some localities that thor- 
oughbred birds are the exception. This favors the assumption 
that auratus is extending its range into the cafer region, and 
the absence of such an invasion of mixed individuals northward 
indicates that the transmigration is in the historic direction, from 
north to south. 
This, with a few interpolations of my own sums up the evi- 
dence which has induced Mr. Allen and the majority of orni- 
thologists to adopt Baird’s theory to its fullest extent. 
To this I wish to add a few supplementary remarks based on a 
collection of flickers made this year in British Columbia. As 
this series was chiefly collected in the breeding period we are re- 
lieved of the complications caused by the winter migration of 
Alaskan auratus into the region and can rely on the specimens as 
representing the domestic relations of the group. 
Perhaps nowhere is the proportion of hybrids to pure-bred birds 
greater than on the Island of Vancouver. The dark, north- 
western form of cafer found here has so thoroughly assimilated 
the characters of auratus that cafer is the exception and c afer- 
auratus the rule. Nevertheless, pure auratus is very rare on the 
island. I have no specimens of it, but Mr. Fannin of the Vic- 
toria Museum has one, and Mr. Maynard of the same city states 
they are sometimes numerous in the fall. I am, however, from 
the absence of such specimens in collections, inclined to discount 
this statement, in the belief that they will prove to be of impure 
origin also. Indeed it is doubtful if there is much association, 
much less admixture, of thoroughbred individuals of the two 
species either with each other or with hybrids at the present day, 
many which appear pure, especially among the females, being 
of impure extraction. 
Comparing the results of an examination of seventy skins, con- 
tained in the collections of the Academy of Natural Sciences of 
Philadelphia from debatable territory in the west and north- 
west, with the deductions given in Mr. Allen’s admirable paper, 
the following general remarks seem in order : — 
1. The prevailing tendency among hybrid flickers is in the di- 
rection of a symmetrical assumption of the characters of both 
species, examples of asymmetric coloration being rarely present 
and chiefly confined to the females. 
3. A much larger percentage of male than female birds show 
mixed parentage. This indicates either that hybridism in this 
case results in an overproduction of males or a disparity in the 
