Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://www.archive.org/details/cu31924003692435

69.11,866:67.99

- CONTRIBUTIONS FROM THE “ZOOLOGICAL LABORATORY OF THE
MUSEUM oF COMPARATIVE ZOOLOGY. AT
HARVARD COLLEGE.

No, $21,

‘THE RELATION. OF PHOTOTROPISM . TO SW ARMING IN
—THE. HONEY-BEE; APIS: MELLIFERA: L.

By Dwiéu7 E. Minnicz.

From THE Journat or PsycnonroLocy, Vor. I, No.2:

CAMBEIDGE,, ‘MASS. iw. 8. A.
ae pAPRIL, 1920.

59.11.856:57.99

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT
HARVARD COLLEGE.

No. 321.

THE RELATION OF PHOTOTROPISM TO SWARMING IN
THE HONEY-BEE, APIS MELLIFERA L.

By Dwieut E. Minnicu.

From rae JournaL or Psycuonioioey, Vou. II, No. 2.

CAMBRIDGE, MASS., U.S.A.
APRIL, 1920.

H

Reprinted from PsycHosroLogy,
Vol. II, No. 2, April, 1920

THE RELATION OF PHOTOTROPISM TO SWARMING
IN THE HONEY BEE, APIS MELLIFERA L.!

DWIGHT E. MINNICH

The honey bee is remarkable for the extent to which many of
its activities are controlled by light. Observations and experi-
ments demonstrating the strong photopositive responses of this
animal have been detailed by Lubbock (’82, p. 278, 279, 284),
Graber (’84) and Hess (13a, ’13b, 717). And indeed this feature
of behavior must have been patent to many of the earlier workers,
so strikingly and constantly is it exhibited.

While conducting some experiments on the photic behavior of
bees several years ago, I was greatly impressed by the strong,
positive reaction to light which normal individuals almost
invariably displayed. Bees in an active state of locomotion, or
easily excited to such, exhibited an orientation which, for its
rapidity of accomplishment and its accuracy of maintenance,
was most spectacular. I say bees exhibiting vigorous locomo-
tion, for, obviously, bees which are torpid and do not move
freely—a condition frequently encountered during cool, damp
weather—cannot show phototropism. Even the moribund con-
dition seemed often to intensify rather than to weaken photic
behavior, and bees scarcely able to creep were observed making
a final struggle toward the light.

My experiments were carried on well into the autumn, when
it became more and more difficult to obtain bees in the field as
the flowers became less abundant. I, therefore, installed a
single comb of worker bees without queen, in a glass observation
hive. The hive was kept darkened by means of small wooden
covers fitted to the glass sides, and the exit was covered with
a bit of screen wire to prevent the escape of the bees. Animals

1 Contributions from the Zodlogical Laboratory of the Museum of Comparative
Zoélogy at Harvard College. No. 321.

177

178 DWIGHT E. MINNICH

could be kept in this way in reasonably good condition for a
month to six weeks, food being provided in case there was not
sufficient in the comb. It was on these bees that I made the
observations to be detailed in the present note, which I believe
afford some evidence on the question of swarming and its rela-
tion to light.

The strong positive phototropism of individual bees is also
characteristic of certain activities of the hive asa whole. Kellogg
(03) was the first to call attention to the fact that swarming
bees are strongly positive to light. He says (p. 694), ‘That
the issuance from the hive at swarming time depends upon a
sudden extra development of positive heliotropism seems obvious.
The ecstasy comes and the bees crowd for the one spot of light
in the normal hive, namely, the entrance opening. But when
the covering jacket? is lifted and the light comes strongly in
from above—my hive was under a skylight—they rush toward
the top, that is toward the light. Jacket on and light shut off
from above, down they rush; jacket off and light stronger from
above than below and they respond like iron filings in front of
an electro-magnet which has its current suddenly turned on.”
These observations leave no doubt as to the strong positive photo-
tropism of swarming bees. The statement, however, that the
issuance of the swarm is dependent upon a “‘ sudden extra develop-
ment” of positive phototropism has met with some difference of
opinion.

Thus von Buttel-Reepen has objected to this interpretation
on the ground of a particular swarm instinct. He says (15,
p. 168)“. . . . so ist in diesen Momenten [the emergence
from the hive at swarming] nicht ein besonders starker Helio-
tropismus die Ursache, sondern die Schwarminstinkte -dringen
die Bienen in das Freie.” Another objection, and I believe a
much more important one, is suggested by a statement of Hess
(13 a, p.663). ‘‘Meine Versuche zeigen, dass die Neigung der
Bienen, zum Hellen zu gehen, nicht auf die Zeit des Hochzeits-
fluges beschrinkt ist.” This contention of Hess—that the

* Kellogg had a glass observation hive covered with a black cloth jacket.

RELATION OF PHOTOTROPISM TO SWARMING IN THE BEE 179

manifestation of photopositiveness is not confined to any given
period, such as the nuptial flight, has been amply confirmed in
my observations. I have already called attention to the fact
that among individual bees an active animal exhibits, almost
without exception, strong positive phototropism. Large aggre-
gates of bees also show marked positive light reactions quite
aside from swarm activities, as the following observations clearly
show.

The glass observation hive with its single comb of bees was
situated at a south window where it was exposed to the sun
during the morning hours. With the oncoming of the cool days
of late October and early November, the bees became much less
active. On bright days, however, the exposure to the warmth
of the sun, and the corresponding rise of temperature within the
hive, served to activate the colony until most of the bees were
moving about the walls of the hive in a rapid uneasy manner.
If at such a time the cover was removed from the end nearer
the window, thus admitting the light, there was with the first
penetrating rays, a sudden increase of the hum within. There-
upon ensued a scene no less spectacular than that described by
Kellogg (’03, p. 693). His words picture it exactly, ‘.
the whole community of excited bees flowed—that is the word
for it, so perfectly aligned and so evenly moving were all the
individuals of the bee current—,” toward the illuminated side.
A few hours later, however, when the sun had passed from the
‘hive and the temperature had fallen, particularly on the cooler
-days, the uncovering of one end of the hive elicited no such
response. With perhaps the exception of a very few individuals,
the bees remained quietly in the swarm cluster. Nor was this
failure to obtain a response a result of the lowered intensity of
light, for the active worker bee responds to a fairly low intensity.
It must, therefore, have been due to the difference in temperature.

These facts, together with those previously stated, demon-
strate conclusively that the pronounced phototropism, so con-
spicuous in swarming bees, is not confined to the period of
swarming. This condition of photosensitivity appears to remain
fairly constant at all times in the animal, although active locomo-

180 DWIGHT E. MINNICH

tion and the absence of other strong, distracting stimuli are
necessary to its demonstration. The situation here differs
from that described by Loeb (’90) for winged male and female
ants, in which positive phototropism is confined exclusively to
the period of the nuptial flight.

We may agree with Kellogg, therefore, that the issuance of
bees from the hive at swarming may be a simple exhibition of
positive phototropism, but it is not the result of a sudden increase
in phototropism. The sudden increase is in the activity of the
animals. Consequently, the fundamental factors in swarm
behavior are those which effect a condition of heightened ac-
tivity, a condition in which locomotion is generally controlled
by light. In my own observations the state of heightened activity
doubtless arose from the conditions of temperature and the pre-
vention of the bees from making their accustomed flights for
defecation, etc. The factors which activate the swarm are not
known. They may consist of particular swarm instincts, as
von Buttel-Reepen (’15) has suggested, or they may even be
more simple reflexes of as yet unknown nature. In any case,
the eviderice seems clear that, although phototropism may be
an important feature of swarm behavior, it is neither peculiar
to this activity nor the primary causal agent of it.

REFERENCES

Burret-Regeren, H. von 1915 Leben und Wesen der Bienen. Braunschweig,
8vo, xiv + 300 pp.

GraBER, V. 1884 Grundlinien zur Erforschung des Helligkeits-und Farben-
sinnes der Tiere. Prag und Leipzig, 8vo, viii + 322 pp.

Hess, C. 1913a Gesichtssinn. Handb. vergl. Physiol. von Hans Winterstein
iv, 555-840. ;

Huss, C. 1913b Experimentelle Untersuchungen tiber den angeblichen Farben-
sinn der Bienen. Zool. Jahrb., xxxiv, Abt. allg. Zool. u. Physiol. der
Tiere, 81-106.

Hess, C. 1917 New experiments on the light reactions of plants and animals
Jour. Animal Behavior, vii, 1-10. ;

Kettoce, V. L. 1903 Some insect reflexes. Science, N. S., xviii, 693-696

Lozs, J. 1890 Der Heliotropismus der Thiere und seine Uebereinstimmun
mit dem Heliotropismus der Pflanzen, Wurzburg, 8vo, 118 pp :

Luspock, J. 1882 Ants, bees and wasps. New York, 12mo, xix + 448 pp

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD
COLLEGE. ( Continued.)

E. L. Marx, Detrector.

*,* Abbreviations used :—.

, B.M.C.Z.......... for Bull. Mus. Comp. Zou.
P.A.A. «64.4.4. 4. for Proceed. Amer. Acad. Arts and Sci.
P.B.S.N.H...... .. .« »for Proceed. Bost. Soc. Nat. Hist.

Nors. — Copies of the List of Contributions, Numbere 1-276, wili be
sent on application.

277. Wernrion, D. H.— Notes on the Reactions of Bivalve Mollusks to Changes in
Light Intensity: Image Formation in Pecten. Jour. Anim. Behavior, 6 (4):
297-318. July-Aug., 1916.

278. Any, L. B.—The Influence of Light and Temperature upon the Migration o1
the Retinal Pigment of Planorbis trivolvis. Jour. Comp. Neurol., 26 (4) 859+
389, 1 pl. Aug., 1916.

279. Waron, A. C.— Reactions of Paramoecium fandatads to Light. Jour. Anim.
Behavior, @ (5) :335-340. Sept.-Oct., 1916.

280. Watron, A. C.— The ‘Refractive Body’ and the ‘Mitochondria’ of Ascaris
canis Werner. Proc. Amer. Acad. Arts and Sci., 52 (5) : 253-266, 2 pls. Oct.,
1916. :

281. Parker, G. H., anp Trrus, E.G. — The Structure of Metridium (Actinoloba
marginatus Milne-Edwards with Special Reference to its Neuro-muscular
‘Mechanism. Jour. Exp. Zodl., 21 (4) :483-459,1 pl. Nov., 1916.

282. Parker, G. H.—The Effector fans of Actinians. Jour. Exp. Zodl., 21 (4):
461-484. Nov., 1916.

283. WaLtoNn, A. C.— A Case of the Occurrence of Ascaris isinuetee Schrank in Dogs.
Jour. Parasitol., $ (1):39-41. Sept. [Nov.], 1916.

284. Parker, G. H. —Nervans Transmission in the Actinians. Jour. Exp. Zoul., 22
(1):87-94. Jan., 1917.

285. Parker, G. H.—The Movements of the Tentacles in Actinians. Jour. Exp
Zool., 22 (1) :95-110. Jan., 1917. :

286. Parker, G. H.— Pedal Locomotion in Actinians. Jour. Exp. Zodl., 22 (1) :111-
124. Jan., 1917.

287. Parker, G. H.— The Responses of Hydroids to Gravity. Proc. Nat. Acad. Sci.,
3 (2): 72-78. Feb., 1917. ‘

288. Coz, W. H.—The Reactions of Drosophila ampelophila Loew to Gravity, Cen-
trifugation, and Air Currents. Jour. Anim. Behavior, 7 (1) :71-80. Jan., 1917.

289. OLMSTED, J. M. D.— Geotropism in Planaria maculata. Jour. Anim. Behavior,
7 (1):81-86. Jan. 1917. _

290. PARKER, G. H.— Actinian Behavior. Jour. Exp. Zoil., 22 (2) :193-229. Feb.,
1917.

291. RepFiELD, E.S. P.—The Rhythmic. Contractions of the Mantle of Lamellibranchs.
Jour. Exp. Zoél., 22 (2) : 231-239. ‘Feb., 1917.

292. Rep#FiEeLp, A. C. — The Reactions of the Melanophores of the Horned Toad.
Proc. Nat. Acad. Sci., 3 (3) : 202-203. Mar., 1917.

293. REDFIELD, A.C. —The Codrdination of the Melanophore Reactions of the Horned
Toad. Proc. Nat. Acad. Sci., 8 (3) : 204-205. Mar., 1917.

294. Pops, P. H.—The Introduction of West Indian Anurainto Bermuda, Bull. Mus.
Comp. Zoél., 61 (6) :117-131, 2 pls. May, 1917.

295. Van Heusen, A. P.—The Skin of the Catfish (Amiurus nebulosus) as a Re-
ceptive Organ for Light. Amer. Jour. Physiol., #@ (2) :212-214. Sept., 1917.

296. Parker, G,H., anp Van Heusen, A. P. — The Responses of the Catfish, Amiurus
nebulosus, to Metallic and Non-metallic Rods. Amer, Jour. Physiol., 44 (3):
405-420. , Oct., 1917.

297. Parker, G.H.— The Pedal Locomotion of the Sea-Hare Aplysia californica.

, dour. Exp. Zodl., 24 (1) :189-145. Oct., 1917.

298. PaRKER, G. H., anp Van HzvseEn, A. P.— The Reception of Mechanical Stimuli
by the Skin, ‘Lateral: Line Organs and Ears in Fishes, especially i in Amiurus.
Amer. Jour. Physiol., #4 (4) :463-489. Nov., 1917.

299. Parker, G. H. — The Power of Suction in the Sea-Anemone Cribrina. Jour. Exp.
ZoGl., 2& (2) : 219-222. Nov., 1917.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD

COLLEGE. (Continued.)

300. Parker, G. H.—The Activities of Corymorpha. Jour. Exp. Zodl., 24 (2) :303-
331. Nov., 1917.

301. SrrinegR, C. E.—The Means of Locomotion in Planarians. Proc. Nat. Acad.
Sci., B (12) :691-692. Dec., 1917. ;

302. Onmsrep,J.M. D.—The Regeneration of Triangular Pieces of Planaria maculata.
A Study in Polarity. Jour. Exp. Zodl., 2 (1) :1657-176. Feb., 1918. ;

303. ; Hecut, S, —The Physiology of Ascidia atra Lesueur. I. General Physiology.

304. { II. Sensory Physiology. Jour. Exp. Zobl., 25 (1) :229-299. Feb., 1018.

305. Hxont,S.—Id. IIL. The Blood System. Amer.Jour. Physiol., 45 (3) : 167-187.
Feb., 1918.

306. Bray, A. W. L.—The Reactions of the Melanophores of Amiurus to Light and
Adrenalin. Proc. Nat. Acad. Sci., & (3) :58-60. Mar., 1918.

807. Watron, A. C.— The Odgenesis and Early Embryology of Ascaris canis Werner.
Jour. Morvh., 3O (2) :527-603. Mar., 1918.

808, OLmsTED, J. M. D.— Experiments on the Nature of the Sense of Smell in the
Common Catfish, Amiurus nebulosus (Lesueur). Amer. Jour. Physiol., £6
(5) 448-458, Aug., 1918. i

309. Ruprim.p, A. C.—The Physiology of the Melanophores ot the Horned Toad,
Phrynosoma. . Jour. Exp. Zobl., 26 (2) :275-338, July, 1918.

310. Brooxs, E.S.— Reactions of Frogs to Heat and Cold. Amer. Jour. Physiol.,
46 (5) 1498-501. Aug., 1918.

811. Cons, P. H.— Autonomous Responses of the Labial Palps of Anodonta. Proc.
Nat. Acad. Sci., & (8) : 234-235. Aug., 1918.

312, Irwin, M.—The Nature of Sensory Stimulation by Salts. Amer. Jour. Physiol.,
A'? (2) :265-277. Nov., 1918.

313. Parker, G. H.—The Rate of Transmission in the Nerve Net of the Coelenterates.
Jour. Gen. Physiol., 1 (2) :231-236. Nov., 1918.

314. Bienny, A. J.—The Effect of Adrenin on the Pigment Migration in the Melano-
phores of the Skin and in the Pigment Cells of the Retina of the Frog. Jour.
Exp. Zo@l., 27 (8): 391-396. Jan., 1919.

315. Jorpan, H.— Concerning Reissner’s Fiber in Teleosts. Jour. Comp. Neurol.,
30 (2):217-227,1 pl. Feb., 1919.

316. Parker, G. H.—The Organization of Renilla. Jour. Exp. Zoél., 2'7 (4): 499-
607. Feb., 1919. ‘

317. Hunt, H. R.— Regenerative Phenomena following the Removal of the Digestive
Tube and the Nerve Cord of Earthworms. Bull. Mus. Comp. Zo6l., 62 (15):
569-581, 1 pl. Apr., 1919. /

318. Davis, D. W.— Asexual Multiplication and Regeneration in Sagartia luciae
Verrill. Jour. Exp. Zodl., 28 (2):161-204, May, 1919. ;

319. ParRkER, G. H.—The Effects of the past Winter on the Occurrence of Sagartia
luciae Verrill. Amer. Nat., 53 (626):280-281. May-June, 1919.

320. Munnicu, D. E.—The Photic Reactions of the Honey-Bee, Apis mellifera I.
Jour. Exp. Zodl., 29 (3):3438-425. Nov., 1919.

821, Munnicu, D. E.—The Relation of Phototropism to Swarming in the Honey-Bee,
Apis mellifera L. Jour. Psychobiol., 2 (2) :177-180. April, 1920,

- CONTRIBUTIONS FROM” THE: ZOOLOGIOAL, LABORATORY OF

| THE MUSEUM etiam iia tOOLOGY AT HARVARD —
, _ CORUESE, (Cont ed. ee oe

zB iL | Max, Directo!

" » Abtivertolions aed ts =

~ BMQ.Z. 6 oe 0's soos for Ball, ites, Coun: 26a, . ;
“PrAshs aaa Pope ee for’ Proceed. Amer, Acad: Ayts and Sei.
3 BBNE. set's oo oy for Proceed. Bost, Soc. Nat, Hist:

i“ Nots.— Copii of the ‘List of: Oontribiutions,: umbere 1276, sot be

Sg

ant. ‘Wanton, D. Ha ; Changes in
: Light - Intenai ay * = oration I fo Pocten, Toure. = Behsvior, 6 (a):
297-818." July-Aug., ot
218. _ Anny, LL.B The Influence of Light and te aperainee upon. the Pleat or
‘the Retinal Pigment of Planorbis | trivolvis. :BBOS
_ 880, Tpl. Ang., tie.
‘279, Wauron, A, OC, . — Reactions of Sisrationstien caudatnin to Light. Jott: Anita
: Behavio: : @ (5); 885-340: Sept-Oct, ‘916. - : dag ‘
280. “Wauron, A. C. —‘the: * Refractive Body pind. ‘the: “Maitichionasia* of Ascaris =
canis Wormers Proa,’ Amer. Acad. Bath and Sel, SH (5) : 268-266, 2'pls. Oct.

: . 1946. ‘
7 BBL. Paxkun, ¢ ‘e. H., axp Trrvs,. B GT. acuie: of Metridium: ‘(Actinoloba :
: ‘“inarginatas_ Miine. Edwards with Special Reference to ats Neuro-muscular we
- | Mechanisin. Jour. Exp. Zabl-, a1 (4) 1438-450, 1pl Nov.,1916;

"939. PxrKer, G. H.—The Hector | By eera of Ag i aa Exp. Zoiley a1 (4):
. 461-484, |. Nov,5 1916. 5 1 :
“288,,, Wazrow, A.C. Gage of the Occurtence of Ascaris tcigtea Scraak in Dog.
a Jour. Paraiitol., $ ay? O41, § spt. [Nov.], 1916..°
284. “PARKAR, G. H,—Nervous Tranemise jon in the Actinians. To. Exp: Zobl., , 22
+ (1) :87-04, Jan. 1007.
236, Phaser, G. H.— The Movements of the Tentucles “in Koltieca,- Tours, ap
Zod, BB eG) 295-110.

987. Bannan, cup
by - # @: 8, “Febs, 1917.

trifugution, ana Air Currents Téur. Rae eae (1): 71-80, Jan, ‘1917.
= Geotropism in Planaria aboiiats, dom: Anim. Behavior, {

xP. Pans 22 oe :106-a20, Feb. sy

_ “Jour. Exp. Zi
ie 292, “Blepmmp,- Bi! sia
: “Broe. Nat. . Acad, Sck:, 3. (3) re 202-208. ‘Mac /19lT.: ig

“g9s. , Buby, AW. —tuetsbednatad of the Melanophore Reaction of le ome

~The Skin 0 of: tho Cutts anlar nabalonists 85.4 Re-;
(as Lae Bi p1017.:

i ied 4 preety
~ 4054205 et
pate + Panes 6

*

ake ae i

Parkise,, @ The Bove nh)
Zigiils, BH (2): Bi9-#s

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY "ie HARVARD.

_ COLLEGE. (Continued.). Ae es

500. Parker, G. H.—The wctivities of Corymorpha Tour. Exp. casa 24 (2): 308
: 381. Nov., 1917. --° |, P
301. Srainczr, C. E.—The iteanee of Casinbiion: in Planarians.. Proc. Nat. Acad.
\ Sci., 3 (12): 691-692. . Dec., 1917. ~
“302. , OLMaTED, J. M. D.—The Regeneration of aeiasgsilar Pieces of Planaria maculata.”
; A Study in Polarity. Jour. Exp. Zodl., 25 (1): 157-176. Feb. 1918. ay tee
308. ; Hacut, S. —The Physiology’ of. Ascidia atra Lesueut. I. General Physiology. r
304. a H. Sensory Physiology.~ Four. Exp. Zobl., B5'(1): 229-299. Feb., 1918. - -~
206. Huont,$8.—~Id. IIL. ae Blood System. - antes Jour.] nysiol., 45 (3): 157-187.
Feb., 1018. Se Be oad
306. Bray, A. W. Le The Secnan af the” Mclanophores of Amiurus to Light and
Adrenalin. Proc. Nat. Xeaa. Sci., 4 (3) 58-60, Mar., 1918 -~ }
307, Watton, A. C. —The Odgenesis and Har ly Embryology of ‘Ascaris: ‘eanis Werner. ‘
- Jour, Morbh.. 30 | (2) 2527-608. Mar., 1918. ~~
308. Omsrxp, J. M. D.— — Expériments on “the Nature of the Sense of Smell i in the __
‘Common Catfish, Amiurus Henson (Lesueur) é Amér.. Jour. Physiol, 46
(5) 1448-458. Aug., 1918. Te a
309. REDFIELD, A. C.—The. Physiology of the-Melanophores ot the Homed Toad, » 5
Phrynosoma.’ Jour. Exp. Zoil., 26 (2): 275-333. July, 1918. - a ee =
810, Buooxs, BE. S.— Reactions of Frogs to. Heat and Colds, A x. Jour, Physiol es
* 46 (5) 1493-501. Aug.,1918.. ee :
811. Cons, P. H.— Autonomous Responses of the” Labial- Palps of Anodonta. Proes. :
"Nat. AGads Set, @ (8) 1284-285. Aug. 1018. fe
312. Inwin,M.—The Nature of Sensory. Stimulation by Sate, Amer. a ons Physiol :
_ ae (2): 265-277. Nov., 1918. ie
313. Parker, G. H. —Tiie, Rate. of Transmission in nthe Nerve Net of the Coclentenates. A
Sours Gen. Physiol. vy (2)+231+4 +236. ~ Nov.; 1918. et
aM, Brower, Awe ‘I. —The Effect of Ady enin onthe’ Pigment eaten in tive “Melano-
-phiores of the. Skin and i in the Pigment Cells of the Retina. of the, Frog. Te our.
Exp. Zobl., 2% (8): 391-396.. Jan,,1919. ~~ ieee
~ B18. Jorpan, H.— Coneerning. Reissnei 3 Fiber id Teleosts: Pex Comp, Neurol.,
oo 0 5 BO (2): 217-227, lpi.’ Feb., 1919...
316. PARKER, G. H. aan. - Orypuization ‘of Renilla. Jour. Exp. Zo'l., ee a 499
a8 507. Feb., 1919, * a
817, Honr, H.R. <a ative, Phoniomesia following ‘the, Removal of the. ‘Digeitive=
Tube atid the Nerve Cord ‘of Earthworms. Bull. Mus, Comp. Zo. e2'6): =
=. 569-581, 1 pl.- Apr., 1919. ~ _ ze oe :
818... Davis, D. WwW. Asexual caning and» “Regenera on in Sagartia -luciae :

. Werrill. Jour. Exp. Zobh, 28 (2) ): 161-204.- May,1919. = a)
a. EsEEaR: G. H.—The- Effects of the-past Wintet on’ the Occurrence of Sagartia 7
ae ‘Iuciae Verrill. ~ Amer. Nat., 53 (626): 280- 281... May-June, yol9, SN

320, MINNICH, D. E.—The Photic Reactions of” the- Honey-Bee, Apis. mellifera. I.
Jour-Exp. Zobl., 20 (3) :343-425." Nov., jl,

321. “MINNICH, D. B.—The Relatiowof Phototropism to Swi timing in ‘the HoneyBee, i
_ Apis mellifera L. Jour. ‘Psychobiol., 2 (2): 177-180; April, 1920,

59.11.866:57,99

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT
HARVARD COLLEGE.

No. 3820.

THE PHOTIC REACTIONS OF THE HONEY-BEE, APIS"
MELLIFERA L.

By Dwieut E. Minnicu.

From THE JouRNAL oF ExPERIMENTAL Zoé.Loecy, Vou. XXIX, No. 3.

CAMBRIDGE, MASS., U.S.A.
NovemBer, 1919.

AUTHOR'S ABSTRACT OF THIS PAPER ISSUED Reprinted from Tur Journat or EXPERIMENTAL
BY THE BIBLIOGRAPHIC SERVICE, SEPTEMBER 29 Zodwoaey, Vol. 29, No. 3, November, 1919

THE PHOTIC REACTIONS OF THE HONEY-BEE, APIS
, MELLIFERA L.

DWIGHT E. MINNICH

SEVENTEEN FIGURES

CONTENTS

Ts Introductions. <)cs.5-vscme ¢ sew eewale veccad aesly daowgdeh Pa eh Ales Gana bales 343
II. Literature................ fs Mas oe ale psp oti ae erp oda st DE 344
IIT. Apparatus and methods............ 0.0.0 c cece cece ence eee e ea ees 350
EV a Materialist uss cae oa san noe cabanas east geken aie Sees Gilets Se esta 358
V. Behavior of normal bees..... yee ia tananla Ae Niet yates Sete aetna diy 360
VI. Behavior of bees with one eye blackened.................2.00000000- 371
VII. Variability of photic response..........0. 0.00 cece cence eee teens 391
VIII. Nature of photic orientation.............. 000.00. c cece e ee eee eee 403
IX. General summary and conclusions.................00000c cee eeeeeaeee 410
XM, Biblio graphy assessors cen pagah vee veuialy veins odin aoe ug wea weve vos 412
DCL, Appendix ingyen «caper hna ca daied shee PUR SHOE TMS eo eae es 415

I, INTRODUCTION

The circus movements produced by blackening one eye in cer-
tain arthropods have long been familiar to zodlogists. It was
not, however, until the advent of more recent interpretations of
behavior, that they received any considerable attention. Then
for the first, the significance of their relationship to normal orien-
tation was recognized. It became apparent that the nature of
the stimulus involved in the two cases was the same. Obviously,
therefore, the application of any general theory of photic orien-
tation to those forms in which circus movements occurred de-
pended upon its ability to explain this phenomenon satisfactorily.
This consideration has led, within the last few years, to a number
of more or less extensive investigations of these reactions.

When the present researches were begun there had been no
attempt to study circus movements quantitatively. During the

1 Contributions from the Zodlogical Laboratory of the Museum of Compara-
tive Zodlogy at Harvard College, no. 320.

343

344 DWIGHT E. MINNICH

progress of the experiments, however, Dolley (16) has published
a contribution to this phase of the subject. His methods as well
as his results, on Vanessa, differ widely from those to be de-
scribed for the honey-bee. Although in his experiments, as in
mine, the illumination employed is defined as non-directive, it
was very unlike in the two instances. The results obtained by
Dolley are described in terms of circus movements of greater or
lesser ‘angles of curvature;’ those obtained by the writer, in terms
of degrees turned per centimeter. The conclusions drawn in the
two papers are also widely divergent.

It is a pleasure here to acknowledge my deep indebtedness to
Dr. G. H. Parker, at whose suggestion this research was under-
taken and with whose helpful criticism it was carried on. I wish
also to express my gratitude to Dr. E. L. Mark for the courtesies
and privileges of the Zodlogical Laboratory.

II. LITERATURE

As early as 1796, Goeze? (p. 42) recorded the fact that a hornet
in which one eye had been painted over with an opaque varnish
always flew toward the uncovered eye. Some years later, Tre-
viranus (’32, p. 194) described an experiment in which the lower
half of the right cornea of a dragon-fly was carefully cut away
from the optic nerve, with the result that the animal moved toward
the left side.

Decidedly the most interesting of the earlier observations are
those of Dubois (’86) on a phosphorescent elaterid beetle of the
genus Pyrophorus. This insect responds positively to at least
certain intensities of light, and according to Dubois (p. 209) it
is most affected by the yellow-green rays, which also predominate
in the spectrum of its own light. The photogenic organs are three
in number, one occupying a median ventral position on the first
abdominal segment, the other two being situated on opposite
sides of the prothorax near its dorsolateral edges. Whenever
the beetle begins to creep spontaneously in the dark, the pro-
thoracic organs become luminous. During flight the abdominal
organ does likewise.

° [have not had direct access to this work. The above ri i
2 eferenc
a footnote in Treviranus (’32, p. 193). Porn eer

PHOTIC REACTIONS OF HONEY-BEE 345

Dubois (p. 208) found that upon completely obscuring the
light from the prothoracic organ of one side of the body with a
covering of black wax, the beetle no longer crept in a straight
line. Smoked paper records, made in a dark room, showed that
such individuals crept in circles toward the functional eye. A
check experiment, moreover, showed that the results obtained
were not due to the weight of the wax. If instead of eliminating
one of the prothoracic organs, the cornea or the entire eye of one
side was destroyed with a red-hot needle (p. 211), very similar
results were obtained. When, however, both photogenic organs
of the prothorax were obscured or both eyes were destroyed, the
animal crept in a hesitant, irregular fashion, presently stopping
altogether.

Dubois has interpreted these results from an anthropomorphic
viewpoint, as evidenced by his original paper and by a more
recent comment (’09). To the present writer, however, these
responses of Pyrophorus afford not only a typical case of circus
movements, but one of considerable theoretical importance as
well. The tendency to circle attendant upon the suppression of
one photogenic organ or the destruction of one eye may be attrib-
uted to the unequal stimulation on the two sides of the body.
If this be correct, the case is indeed unique, for the beetle is ori-
ented by its own luminosity. This, of course, in nowise affects
behavior in the normal animal. With a photogenic organ on
each side of the prothorax producing light of the same quality
and intensity, it is always perfectly oriented with respect to its
own light. But if the source of light or the photoreceptor of one
side be eliminated, the beetle promptly orients toward the oppo-
site side, the side which is receiving the greater stimulation.

In recent years, a steadily increasing number of arthropods
have been shown to exhibit circus movements when one eye is
blackened or destroyed. The researches of Bethe (’97 a), Axen-
feld (99), Holmes (’01, ’05), Radl (’01, ’03), Parker (’03), Had-
ley (08), Carpenter (’08), Brundin (13), Holmes and McGraw
(713), Dolley (16), and Garrey (717), have demonstrated conclus-
ively that among phototropic arthropods generally, unilateral
photic stimulation results in a more or less asymmetric response.

346 DWIGHT E. MINNICH

These investigations have covered between fifty and sixty spe-
cies, including the four chief classes of arthropods. Among the
insects, where most of the work has been done, representatives
of most of the larger orders have been experimented upon. These
embrace Orthoptera, Blattoidea, Hymenoptera, Coleoptera,
Odonata, Lepidoptera, Diptera, Homoptera, and Hemiptera.
The phenomenon of circus movements—or perhaps better, asym-
metrical response—must, therefore, be regarded as general rather
than exceptional for the members of this phylum.

The form of response naturally varies with the peculiarities of
locomotion in a given species. It is not the same for a sidewise
moving crab, such as Carcinus, as it is for an insect which moves
forward. With the usual type of forward locomotion, however,
arthropods with one eye blackened generally circle toward the
functional eye, if they are positively phototropic; toward the non-
functional eye, if they are negatively phototropic.

It is true there are cases which, on first examination, do not
appear to conform to this generalization. Thus Holmes (’05, pp.
332-336) has demonstrated clearly that an animal with one eye
blackened may at first perform circus movements in creeping
toward a light, only to modify its behavior after a time and creep
in a straight path. Such was true of both Ranatra and Noto-
necta. Axenfeld (’99, p. 375) had previously made similar
observations, and more recently Brundin (18, pp. 337, 346-348)
and Dolley (’16, pp. 371-382) have demonstrated the same phe-
nomenon in the species with which they worked.

There can be no doubt, therefore, that many arthropods with
one eye blackened are able in time to modify their behavior to
light. This, however, in nowise lessens the significance of the
initial tendency of the animal to perform circus movements. In
fact, this initial tendency is the all-important one as far as the
question of orientation in the normal animal is concerned. Ido
not believe, therefore, that the presence of modifiability in an
animal warrants considering its behavior as an exception to the
general occurrence of circus movements.
a ee

ered in the behavior of cer-

PHOTIC REACTIONS OF HONEY-BEE 347

tain flies. Thus Radl (’03, p. 62) says, ‘Die Calliphora vomi-
toria bewegt sich fast ebenso gerade mit einem geschwirzten Auge,
wie wenn sie aus beiden sieht, und es ist mir nicht leicht, diese
Erscheinung zu erkliren.’’ Carpenter (’08, p. 486) states that
Drosophila with one eye blackened ‘‘crept in a fairly direct path
toward the light, although a tendency to deviate toward the
side of the normal eye regularly occurred.” It is possible, I
believe, to interpret these cases as merely more extreme instances
of modifiability, in which regulation occurs very rapidly instead
of after a more or less prolonged experience.

That modifiability is operative, at least in the case of Droso-
phila, is evidenced by the following statement of Carpenter (p.
486). ‘The tendency to diverge from the direct path toward the
side of the uncovered eye was overcome by a series of short, quick
turns in the opposite direction, which kept them headed toward
the light.”’ Further evidence in the case is afforded by the be-
havior of one fly which, according to Carpenter, persisted in per-
forming circus movements. This fly, however, (p. 486) ‘had
long been active, and showed signs of fatigue.”’ As will be shown
later, very similar phenomena were observed in the honey-bee.
In conditions, such as that of weakness, induced by. long
experiment, the bee frequently circled much more toward the
functional eye than it had formerly done. It seems probable
that in such states the animal approximates more. nearly to a.
simple, reflex behavior. Factors effective in modifying behavior-
in the vigorous animal have ceased to be operative.

If these interpretations be correct, the conspicuous absence of’
circus movements in Drosophila is only an extreme case of modi--
fiability, and offers no real objection to the general conclusion to.
be drawn from these reactions. However, further work is neces--
sary upon both Drosophila and Calliphora before they may be
disposed of with certainty.

Responses of still another kind have seemed perhaps the most
formidable obstacle to any general conclusion as to the occur-
rence of circus movements. Thus Hadley (’08, p. 197) has shown
that whereas the ‘progressive orientation’ of the lobster larva.
after the blinding of one eye is positive, the larva performs circus.

348 DWIGHT E. MINNICH

movements or turns toward the injured side. Brundin (713, Pp.
346) states that in positive specimens of Orchestia traskiana, clr-
cus movements will occur as often toward the blackened as
toward the normal eye, while Holmes and McGraw (’13, p. 370)
report the case of a positive skipper butterfly which almost inva-
riably circled toward the blackened eye.

A very plausible explanation of these apparent anomalies,
however, has been offered by Dolley (’16, pp. 394-399), who has
shown that the contact stimulus afforded by the material cover-
ing the eye is sufficient to cause Vanessa, when in the dark, to
turn continuously toward the covered eye. This tendency, more-
over, exhibits little, if any, modification from day to day. The
effect of such a contact stimulus is continuous. But in the pres-
ence of photic stimulation of moderate or high intensity, it is quite
overwhelmed by the strong phototropism of the butterfly. In
the case of animals of less certain phototropic index, this contact
stimulus is, in all probability, frequently strong enough to over-
come the effect of light. An examination of the cases cited above
shows that the phototropism of these animals is not of the une-
quivocal kind exhibited by Vanessa. It seems likely, therefore,
that their apparently exceptional behavior was due to contact
and not to photic stimulation.

Suppressions of photic circus movements by responses to other
stimuli are not surprising, when it is recalled with what facility
even the stereotyped circus movements produced through uni-
lateral lesions of the central nervous system may be altered in a
similar manner. Thus Bethe (’97 b, p. 507) states that the ten-
dency of bees to circle toward the normal side after the removal
of one half of the brain or the severance of one of the oesophageal
commissures, may be arrested, and the animal may even be com-
pelled to deviate toward the injured side by stimulating the legs
of the normal side. Moreover, in a general statement concern-
ing the several crustaceans and insects subjected to similar opera-
tions (p. 541), he says,“ . . . nach Aufhebung der Hem-
mung der gesunden Seite durch angebrachte Reize aber auch
spontan bei allen Versuchsthieren gerader Gang und Kreisgang
nach der operirten Seite eintritt.”

PHOTIC REACTIONS OF HONEY-BEE 349

Whether the effect of contact stimulation also accounts for
certain of the phenomena observed by Axenfeld (’99) is not so
clear. Axenfeld reports that nocturnal lepidoptera with one eye
blackened turned toward the blackened eye during the day. In
the same paper he makes the following general statement: ‘‘En-
fin on peut observer que ces mémes animaux photofuges, qui tour-
nent en pleine lumiére du soleil du cété de l’oeil couvert, offrent
le mouvement contraire au soir ou méme de jour, quand ils sont
transportés dans une chambre mal éclairée; . . . .” It
may be that such animals, being attuned to a low intensity, re-
spond positively to it, whereas a stronger intensity evokes a nega-
tive reaction, somewhat according to the idea of Davenport (’97,
p. 197). Certainly, if the circling of the nocturnal lepidoptera
toward the covered eye was a light response, it is not in harmony
with the statement of Loeb (’90, p. 51) to the effect that all ‘day
and night butterflies’ are without exception positively photo-
tropic. I am led to suspect, however, that some of the reactions
noted by Axenfeld were the results of contact stimulus, for Hess
(13 a, p. 651) has shown that Coccinella, which Axenfeld reports
as circling toward the blackened eye, is not negative to light.
Axenfeld’s experiments, therefore, need careful repetition before
any final conclusions may be drawn from them.

It seems quite certain, therefore, that what have appeared to
be exceptions to the general occurrence of circus movements
among phototropic arthropods are not really incompatible with
this view. Taken as a whole, the investigations of these reac-
tions demonstrate rather conclusively that, although they may
be modified through experience or obscured by responses to other
than photic stimuli, they are, nevertheless, to be considered as
characteristic of phototropic arthropods. Photic orientation in
this group of animals, therefore, cannot be accounted for by any
theory which fails to offer a satisfactory explanation of circus
movements.

350 DWIGHT E. MINNICH

III, APPARATUS AND METHODS
1. Directive Light

In the experiments of the present paper, both directive and
non-directive light were employed. Those involving directive
illumination were carried on in a circular area (fig. 1) 2.44 m. in
diameter, which was laid out in black lines on the concrete floor
of a dark room. Sixteen centimeters’ above the center of this.
area, An incandescent lamp was suspended. The lamp employed
was a 100-watt, 115-volt, stereopticon, Edison mazda lamp. Of
several bulbs used in the course of experimentation, only the last
was determined photometrically, its candle-power being approxi-
mately 80. These lamps when new are calculated to furnish
100 e.p., but their efficiency decreases considerably with usage.

In making tests in the directive light area, bees were started
creeping at the outer circumference. The course of the animal
as it traveled toward the light was then traced as accurately as.
possible on a record bearing a plan similar to that of the light.
area and drawn to scale. Such a record is shown in figure 1.

2. Non-directive light

a. Construction. The apparatus employed to furnish non--
directive light consisted essentially of a white-walled, cylindrical.
chamber. This chamber was illuminated by an incandescent.
lamp, the light of which was diffused through a thin, white screen,
suspended a short distance below the lamp. Bees were admitted
to the apparatus through a small, circular opening in the center:
of the floor, and the course of their creeping was then traced as
accurately as possible on a record. The apparatus was espe-
cially designed to afford a creeping animal a continuous photic:
stimulation of uniform intensity over the entire surface of the-
eye. A more detailed description is presented in the following
paragraphs (see figure 2).

* Distances from lamps to creeping surfaces were
mea :
the filament in all cases. Senne eee

PHOTIC REACTIONS OF HONEY-BEE 351

The cylindrical chamber, which measured approximately 84
cm. in height by 87 cm. in diameter, was constructed on a light
wooden framework covered on the exterior with heavy, corru-
gated cardboard. On the interior it was lined with a thickness

Way
~

Fig. 1 Plan of directive light area, showing two trails of anormal bee. Note
the deflection of the courses in the non-directive region near the lamp and directly
beneath it.

of dead white, cotton cloth, backed by a layer of heavy white
paper. On one side of the cylinder, and extending from its bot-
tom edge, a rectangular opening 58 cm. high by 32 cm. wide was
cut through the cardboard and paper layers. The white cloth
lining only closed this opening, and it was here slit from top to
bottom, the bottom edges being left: free. The two flaps thus

352 DWIGHT E. MINNICH

formed allowed free access to the interior of the cylinder. In
onetof them a small opening (fig. 2, 0), 3 by 4 cm., was cut for
purposes of observation.

The top of the cylinder was similar in construction to the side
walls except that the cardboard layer was omitted. Near oppo-
site edges of the top, two circular openings, 8 cm. in diameter,

v v

Zi
LAL TLL LEE CELEEELELLELAEEN XTEEEEEE LZZZ- LAM LLL

Cc h

Fig. 2 Diagrammatic section through non-directive light apparatus. c
transferring cage; @, entrance to light chamber; h, handle of slide opening aed
closing e; 0, opening for observation; s, light screen; v, ventilators

were cut (fig. 2, v). These were covered with a thin, white gauze
of coarse mesh, and served as ventilators, preventing any undue
rise of temperature within the apparatus. The bottom of the
cylinder was formed by a layer of heavy, dead white paper, which
covered the table on which the cylinder stood. This pa ser was
especially selected to afford a good creeping surface os it was
drawn a plan, similar to that shown in figure 3, by nn sene of which
the course of a creeping bee could be accurately followed.

PHOTIC REACTIONS OF HONEY-BEE 353

The illumination of the apparatus resembled the semi-indirect
illumination of a modern house, the light from an incandescent
lamp being diffused through a circular screen (fig. 2, s), 22 cm. in
diameter, of white bond paper. Two intensities of illumination
were employed. The less intense was produced by a carbon
filament lamp of approximately 2 c.p.,4 66 cm. above the floor,
and the more intense by the 80 c.p. mazda lamp previously
described, 33 cm. above the floor. The intensity of illumination
in each instance was measured at three different points on the
floor of the cylinder. One determination was made at the cen-
ter; a second at a point 3 cm. from the right side wall, and a third,
at a point 3 cm. from the left side wall. The results of these
measurements are given in table 1. Hereafter, in referring to the

TABLE 1
A B c D 1s F
INTENSITY ON | INTENSITY ON
CANDLE-POWER | INTENSITY ON FLOOR 3 cM. FLOOR 3 cM. AVERAGE OF-C | AVERAGE OF B
OF LAMP FLOOR AT CENTER|FROM RIGHT SIDE| FROM LEFT SIDE AND D AND E
WALL WALL

c.p. med me. me. me. me.

2.36 25.9 17.93 25.25 21.59 23.75
79.45 1051.5 831.37 894.45 862.91 957.21

two intensities of illumination employed, the averages given in the
table will be used in round numbers. The less intense will be
designated as non-directive light of 24 mc.; the more intense, as
non-directive light of 957 me.

The transference of bees to and from the apparatus was effected
by means of a small, cylindrical cage of wire screen, 5 cm. in
length by 2 cm. in diameter (fig. 2, c). This cage, one end of
which was open, exactly fitted into a circular opening cut through
the table top to the center of the chamber floor. By means of a

4The lamp used throughout experimentation was, unfortunately, broken
before being determined photometrically. Its candle-power was certainly

between 2 and 4.
5 Throughout the present paper, the abbreviation me. will be used to designate

meter candles.

354 DWIGHT E. MINNICH

slide operated by a handle (fig. 2, h), it was possible, after ae
serting the cage, to open or close the light chamber at will. The
difficulties involved in direct manipulation of bees were thus
entirely avoided. An individual to be tested in non-directive
light was merely allowed to creep into the cage, which was then
inserted into the opening in the table top. The slide was then
pushed aside and the bee allowed to creep up on to the floor of the
apparatus. As soon as the bee had entered the light chamber,
the slide was pushed back, closing the entrance and leaving the
floor of the apparatus complete.

The ideal apparatus for studying the effects of continuous pho-
tic stimulation of a constant intensity would be one so constructed
that all the ommatidia of a compound eye would receive equal
illumination, irrespective of the direction of locomotion. Such
an apparatus is virtually. a physical impossibility. However,
the apparatus just described is perhaps somewhat of an approxi-
mation to it, even if it does not afford an absolutely uniform light
intensity over the floor of the light chamber. As table 1 shows,
the illumination is more intense toward the center. Somefluc-
tuation will, therefore, occur in the stimulation of the various
ommatidia as the animal moves. However, in any position
whatever on the floor of such a light chamber, all the ommatidia
are receiving some stimulation. Moreover, the amount of stimu-
lation received by those areas of the eye which are minimally
affected does not differ vastly from that received by’ areas of
maximal stimulation.

b. Records. The method of recording behavior in non-directive
light is illustrated in figures 3 and 4. The animal to be tested
was transferred to the light chamber, and its course of creeping,
observed through the ‘peep hole’ in the curtain, was traced as care-
fully as possible on a record sheet. The record bore a plan simi-
lar to that on the floor of the light chamber, drawn on a scale of
1 to 6. The duration of each trial was ascertained by counting
the rings of an electric bell, attached to an electric clock regulated
to seconds. How long the trial should last was determined by
an interval previously decided upon or by the animal encountering
the side wall of the chamber and creeping up. On completion of

PHOTIC REACTIONS OF. HONEY-BEE 355

a trial, the bee was removed, and the remaining data called for
-on each record were entered. The tracing was marked with
arrows to indicate its direction. Observations on the physical
condition of the animal and others of importance, which were
made from time to time, were also noted on the record. All the
records of a single animal were then filed away together, thus
_affording a permanent record for further reference.

Since it was desired to make a quantitative study of circus
“movements, it was necessary to adopt some method whereby the
-amount of turning exhibited by an animal, in a given trial or
group of trials, might be expressed as a single value. These
values have been stated in terms of average number of degrees
turned per centimeter of progress, and were obtained in the fol-
lowing manner. The length of the trail was first measured with
a map tracer. Several readings were taken until two were ob-
tained with a difference of less than 0.3 cm. These were then
averaged, and the result used in computations. Thus in figure 3,
the length of the orginal tracing is 26.95 cm. Since, however,
the records were on a scale of 1 to 6, and these in reproduction
have been reduced one half, the length of the text figure tracing
must be multiplied by (6 x 2 =) 12 in order'to obtain the dis-
tance actually traveled by the animal.

The various turns or angular deflections of the trail were next
-estimated by reference to the radii of the plan. It is obvious
that in traveling a curved course, the direction of locomotion at
any given instant is the tangent to the curve at that point. For
example, in figure 3 the initial direction of locomotion is shown
by the tangent ata. This direction is parallel to aradius. From
a, the tangent to the curve or the direction of locomotion rotates
continuously to the left until the point b is reached. At b the
tangent is parallel to a second radius, which makes with the radius
of initial parallelism an angle of ; of 360° or 180°. (Each radius
forms angles of 45° or 4 of 360° with its adjacent radii.) In
other words, in traveling from a to b the axis of the animal’s
body has rotated 180° to. the left, or the animal has executed 3
of a complete sinistral loop. Similarly, from 6 to c the course of
the animal makes 12 dextral loops; from c to d, 4 of a sinistral

356 DWIGHT E. MINNICH

loop, and finally from d to e, 14 dextral loops. The total amount
of turning, or angular deflection, toward the right in this trail is,
therefore, 12 + 14 or 23 X 360°, while that to the left is 3 + ¢
or § X 360°.

Since the honey-bee is positively phototropic and in this case
the left eye was blackened, the angular deflection toward the
right or functional eye is designated as positive; that toward the
left or covered eye, as negative. The algebraic sum of these

Animal Phas wutifire,
Experiment No. 12

No, of Animal 3
Date “sf, ’

«nef all AM. |%
Time { 30 ate 4”

Ne am
Bye black Lat <”
Light 24 me. ~\\_
No. dx. loops 1% 14 =IRS_
No. sn. loops 44+ K= % > ai

Trail fength, cm. 21.9
2.95 Ay.

Fig. 3 Record of bee no. 123 in non-directive light.

angular deflections will give a result equivalent to the amount.
of continuous turning required to carry the animal from the start-
ing point to the end of its course. Thus, in figure 3, the direction
of locomotion at a makes with the direction at e an angle of 23
x 360° — § x 360° or 24 x 360°.

Knowing the distance traveled in centimeters and the amount
of turning in degrees, the average degrees turned per centimeter

is easily computed. Denoting this average deflection, as I shall
call it, by D, we have for the trail in figure 3,

PHOTIC REACTIONS OF HONEY-BEE "357

23 x 360°

D = 36.05em. x6

= + 5.01°/ cm.

It is to be emphasized that the value + 5.01°/cm., does not sig-
nify that the animal turned only toward the functional eye. It
merely shows that the algebraic sum of all its deflections aver-
ages 5.01°/cm. toward the functional eye.

Animal Apis medlifine ;
Experiment No. |3
No. of Animal 5
Date Yo, a
Time{ 4 50 Am,”
@so wc KX
bil sag \

aN .
x
Eye black Lolt <<
Light 457m NY
No. dx. loops a % b&rs_
No. sn. loops a ¥ b ¥
Trail length,cm. a jaa 611
122
12.25 We Wd Ae

Fig. 4 Two trails of bee no. 135 in non-directive light.

A record is shown in figure 4 which represents two trials taken
in rapid succession. This was necessitated by the animal’s en-
countering the side wall of the light chamber so quickly that the
first trial was shorter than usual. The deflections in these trails
are estimated as previously described. It will be noted, however,
that in the trail marked a, the angular deflection between m
and 7 does not amount to quite 2 of a sinistral loop, although it is
so counted. In such instances the angle was always estimated

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, NO. 3

358 DWIGHT E. MINNICH

to the nearer } of a circumference, no attempt being made to

discriminate differences of less than 45°. In this record it is

desirable to combine both trails into a single computation. Pro-

ceeding as before,

(+$+%3—2— 4) 360°
(12.25 + 7.1 cm.) 6

D= = 1.16°/cm.

The negative sign of the average deflection here obviously indi-
cates that the bee turned more toward the covered eye than
toward the functional eye in these trials.

In the course of experimentation, records of normal bees were
also made in non-directive light. Since in such individuals neither
eye was blackened, the positive sign was arbitrarily applied to the
direction of greater angular deflection in each set of trials. Other-
wise the computations for normal bees were performed in the
same manner as those for bees with one eye blackened.

These various examples will illustrate the method employed in
all quantitative determinations. Upon the results thus obtained
the chief conclusions of the present paper are based.

IV. MATERIAL
1. General care of animals

The bees used in all quantitative experiments were thoroughly
active workers taken from the flowers of a near-by garden, and
were, for the most part, individuals from a single large hive situ-
ated there. The animals were trapped by simply inverting a
long glass tumbler over the flower, and then transferring them
to a small screen fly-trap. In some experiments, however, which
were performed too late in the fall to obtain bees in this way,
animals were used from a single comb of workers confined in an
observation hive. The exit of the hive was kept securely screened,
for such a colony quickly disintegrates if its members are per-
mitted to leave the hive freely. Bees kept in this way remained
in reasonably good condition, for at least a month.

Bees destined to undergo experimentation were first subjected
to having their wings clipped, an operation easily executed when

PHOTIC REACTIONS OF HONEY-BEE 359

the animals were feeding. Each wingless individual was then
confined in a small cylindrical cage of screen wire, the bottom of
which was formed by a layer of tissue-paper over cotton to pre-
vent injury in case of falling. In the same cage were also placed
two friendly winged workers to counteract any possible effects
of isolation. The cages of bees were kept in a darkened box when
not directly under experimentation, since the influence of light
often caused the animals to maintain a restless activity which
appeared, in some cases, to shorten life considerably. In the
dark, however, they usually remained more quiet.

Each cage was supplied with water by a small wad of saturated
cotton placed on its top. Small quantities of honey were also
supplied on short wooden sticks stuck to the side of the cage.
Early in the morning, at noon, and in the evening the cages
were cleaned by removing excess honey, etc., and fresh honey
and water were provided. Such operations were carried out at
least a half-hour before any trials were made on the animals.

The temperature of the laboratory in most of the experiments
was kept above 20° to 21°C. This was found to be an important
consideration, since at lower temperatures bees became torpid
and inactive. In collecting the animals even, an attempt was
made to take them on warm, sunny days which had, in general,
been preceded by warm weather. It was found that bees brought
in after a brief period of cold, wet weather were apt to be either
unresponsive or extremely variable in their behavior.

2. Blackening the eye

Any technic for blackening the eye of a wingless bee requires,
of course, the use of an anaesthetic. In the present.experiments
ether was used exclusively. Care was taken to administer it
rather slowly and in minimal doses. When completely anaes-
thetized, the bee was placed on one side, on a small cork pinning
board. Here it was fastened down securely by the use of insect
pins, with which the thorax, abdomen, and legs were securely

‘braced against the cork. The blackening was then applied to the
eye, the entire surface being covered with as thick a coat as pos-

360 DWIGHT E. MINNICH

sible. Two kinds of blackening material were used, viz., lamp-
black in shellac and a dead black paint known commercially
as ‘Jap-a-lac.’ The latter proved the more satisfactory and was
used throughout the majority of experiments.

Although bees under ether often began to recover in five to
ten minutes, they were not removed from the pinning board for
twenty to twenty-five minutes, when the covering of the eye was
well hardened. Recovery from anaesthesia was usually com-
plete in an hour and often much less. Asa rule, however, opera-
tions were carried out in the evening, and the bees were not sub-
jected to further experiment until the following day. Ample
time was thus allowed for the animals to recover as much as
possible from the effects of the operation.

V. BEHAVIOR OF NORMAL BEES
1. Kinetic effect of light

The remarkable sensitivity of the honey-bee to photic stimu-
lation must have long been patent to students of its behavior.
Bethe (’98, p. 83) says, ‘‘Das Licht ist bei diesen Tagthieren
[bees, flies, etc.] der auslésende Reiz zum Fliegen; in einer dunklen
‘Schachtel fliegt keine Biene auf, auch nicht, wenn man sie reizt.
Das Licht gibt die Regulirung beim Fluge ab.’’ This observa-
tion was repeatedly confirmed in the present experiments. When
collecting bees from flowers, fifteen to twenty individuals were
confined in a single cage, which was then placed in a closed box.
Although at the height of activity when captured, a few minutes
in the darkness of the box seldom failed to reduce these animals
to a state of quiescence. If a little light was admitted to the box,
however, by even partially removing the lid, there was a sudden
resumption of activity.

Precisely the same behavior was exhibited by wingless bees.
If confined in a dark box, they were, as a rule, reduced to com-
parative inactivity. A brief exposure to light, however, was
usually sufficient to excite vigorous locomotion, and continued
exposure not infrequently resulted in the maintenance of an
intense activity for extended intervals of time.

PHOTIC REACTIONS OF HONEY-BEE 361

Individuals which had been subjected to operations of remov-
ing the wings and blackening the eye frequently responded some-
what more slowly to this photic activation than did normal
bees. In the former, locomotion was preceded by a more or less
prolonged sequence of cleaning operations. The proboscis was
extended and stroked with the fore legs. The eyes, parti¢ularly
the covered one, were the objects of repeated and vigorous scrap-
ings, responses no doubt largely attributable to the irritation of
the blackening material. The abdomen was meanwhile bent
from side to side, while the middle or hind legs were rubbed to-
gether, or the hind legs assiduously stroked the dorsum of the
abdomen. These movements became more and more intense
until at length they culminated in active creeping.

Light, then, exerts a strong activating or kinetic influence
upon the honey-bee, while darkness has the opposite effect. Es-
sentially similar phenomena have been reported by Loeb (’90)
for the plant louse, Carpenter (05) for the pomace fly, and
Turner (’12) for the mason wasp. Stockard (’08) has reported
the case of Aplopus, the ‘walking-stick,’ which also falls into this
category of behavior. In Aplopus, however, light inhibits ac-
tivity, while darkness induces it. Hence the ‘walking-stick’ is
nocturnal, whereas the plant louse, the pomace fly, the mason
wasp, and the hive bee are diurnal.

In diurnal animals this response is apparently due to the con-
tinued action of light rather than a sudden change in it. Thus,
while many bees respond almost, if not quite, at once to the
presence of light, others may respond only after some minutes of
exposure. According to Turner (12, p. 360), the same is true
of the mason wasp.

2. Directive light

Not only does light induce locomotion in the honey-bee, but
directive light regulates the course of locomotion. Bees brought
into the laboratory direct from their. foraging activities out of
doors seldom failed to exhibit a most striking phototropism.
Such insects when liberated in the laboratory flew almost im-
mediately to the nearest window, where they remained fluttering

362 DWIGHT E. MINNICH

against the glass. Or, if escaping in a darkened room, they not
infrequently flew directly into the flame of the nearest gas jet.

Observations of this sort were long ago reported by Lubbock
(82, pp. 278, 279, 284). A few years later, Graber (’84) demon-
strated the same thing experimentally by confining forty to sixty
bees in a small box, one half of which was illuminated by direct
sunlight, the other half being shaded, with the result that the
majority of the bees soon collected in the illuminated end. More
recently, Hess (’13 a, 713 b, ’17) has repeated this and a variety
of other experiments. As a result of these he has been able to
show that in the presence of several sources of photic stimulation,
which differ in color and intensity, bees always orient toward
the one which to a totally color-blind person appears brightest.
The positive phototropism of the honey-bee is thus demonstrable
in a variety of ways.

In the experiments just cited, winged bees were used exclu-
sively. My own experiments, on the contrary, were confined en-
tirely to workers from which the wings had been clipped. Such
bees when creeping in the directive light area exhibited an orien-
tation which was striking in three respects, viz., its rapidity, its
precision, and its constancy.

An individual to be tested was removed from the dark box and
exposed to light for a few minutes until it was thoroughly active.
It was then allowed to creep from its screen cage to a small,
rectangular piece of black paper, and on this it was transferred to
the edge of the directive light area. An effort was made to start
the animal creeping at a right angle to the direction of the light
rays by turning the paper just before it crept off. The rapidity
of orientation was so great, however, that the intervening centi-
meter or so was frequently sufficient to allow the animal to reorient
perfectly. Since the velocity at which bees creep averages 3 to 6
cm. per second, orientation in these cases occurred in considera-
bly less than one second. I have also tried leading a bee by
moving the light, now in this direction, now in that, with varying
degrees of curvature. Always the animal followed, orienting rap-
idly to even slight movements of the lamp.

PHOTIC REACTIONS OF HONEY-BEE 363

The precision with which orientation was maintained was no
less conspicuous. Once oriented, the animal generally moved
in a nearly straight line toward the source of light. In figure 5
are shown two records of each of six bees in the directive light
area. Of a large number of animals tested in the course of ex-
perimentation, considerably over 25 per cent maintained their
orientation as precisely as did bee no. 66. The deviations of

ININ/\
AKA

Fig. 5 Two trails of each of six normal bees in directive light. In this, as in
subsequent figures of records in directive light, the clear circle represents the light
source, and the straight lines from it, the direction of the rays.

most of the animals would, moreover, easily fall within the lati-
tude of that exhibited by bees nos. 66, 33, and 23. Results sim-
ilar to those shown for animals nos. 110 and 21 were, on the con-
trary, less frequently encountered, while trails such as those of
bee no. 36 were seldom or never found among normal, healthy
bees.

The response to directive light is very constant in the bee.
The oncoming of death itself seems often to intensify rather than
to weaken this phase of its behavior. Bees occasionally escaped

364 DWIGHT E. MINNICH

in the laboratory. Such individuals rarely survived the lack of
food for more than a day or so. Yet it was not an infrequent
occurrence to observe one of these starved animals, so weak that it
was barely able to creep, slowly emerging from a hidden corner
in a final struggle toward the light.

Nevertheless, bees were discovered which in a few instances
failed to exhibit the usual positive reaction to directive light.
Suchicases, however, are not to be construed as a total absence

? an

SL

Fig. 6 Three successive records of a normal bee in directive light, showing
failure to orient in two cases.

of phototropism, but rather its momentary suppression by other
factors of behavior. This is well illustrated by the following
example. Seven cages of bees were prepared from the stock in
the observation hive, Oct. 30, at 2:45 p.m. When tested about
an hour later in the directive light area, six of the seven animals
exhibited the usual positive response. One animal, however, gave
the records reproduced in figure 6.

This bee when given its first trial at 4:06 (fig. 6, 1) did not ori-
ent toward the light source. Instead it pursued a devious course

PHOTIC REACTIONS OF HONEY-BEE 365

looping now to the right, now to the left, and finally turning al-
most directly away from the light. In a second trial at 4:14, it
exhibited a somewhat similar response (fig. 6, 2). One minute
later, the animal was subjected to still a third trial, being started
on this occasion some 30 cm. nearer the light. This time it ori-
ented and moved in a fairly direct course toward the source of
illumination (fig. 6, 3). What the temporary, inhibiting factors
were which produced these very atypical responses could not be
ascertained. In all other respects this bee was quite indistin-
guishable from the other individuals in the experiment. This
example, however, shows that even the constant response of the
bee to directive illumination is not free from abrupt and appar-
ently inexplicable departures.

8. Non-directive light

The behavior of bees in non-directive light is no less charac-
teristic than that in directive illumination. Since all quantita-
tive experiments on circus movements were conducted in non-
directive light, an intimate acquaintance with the behavior of
normal animals under the same conditions was necessary. Every
bee was, therefore, subjected to several trials in non-directive
light before having one eye blackened.

It was a matter of continual observation that a bee creeping in
the directive light area ceased to move in a straight course upon
reaching the area near and immediately beneath the lamp.
Here, where the illumination was essentially non-directive, the
animal deflected from its former, precise path and began to loop
in a constant or varying direction (fig. 1). In other words, the
bee was trapped; for directly it crept away sufficiently for the light
to become directive again, it was forced to turn back. Thus the
animal continued to creep round and round in a limited area,
occasionally rearing on its hind legs in an abortive attempt at
flight, or finally ceasing locomotion to begin cleaning operations.

In the non-directive light apparatus (fig. 2), the same tend-
ency. to loop was manifested, only on a much more extensive
scale. Here the bee seldom crept in a.straight line for any great

366 DWIGHT E. MINNICH

distance. Each animal was subjected to two sets of trials, an
hour or so apart. Usually a single trial only constituted a set.
In case the bee quickly encountered the side wall of the light
chamber, however, or exhibited unusual variability in its be-
havior, additional trials were made. The aggregate duration of
the trials of each set varied considerably, even in the same animal.
Sometimes they were as short as thirty seconds; again, as long as
two minutes. The average was in the neighborhood of thirty
to sixty seconds. Preliminary to each trial, the bee was exposed
to light until aroused to active creeping. The illumination used
throughout in experimenting with normal bees was 957 mc.5

The average deflection to the right or to the left has been
computed for each set of records thus obtained, and the results
of these computations presented in table 2 (appendix), columns B
and C. On the basis of these data, the fifty-two bees experi-
mented upon may be classified into three groups:

1. Bees whose average deflection in both sets of trials was over
2°/cem. and in the same direction.

2. Bees whose average deflection in both sets of trials was
small.

3. Bees whose average deflection in the two sets of trials varied
widely, either in magnitude or direction, or in both.

The first class is composed of animals which exhibited a more
or less pronounced tendency to turn in a constant direction (right
or left). These animals, 29 in number, comprised 56 per cent
of the total 52 bees. Fourteen of these were chiefly right-handed
in their turns; 15, left-handed. In 14 of the 29 bees, or 27 per
cent of the total number, the average deflections exceeded 4° /em.,
while in 6 individuals, or 12 per cent, it rose to over 8°/em. Sim-
ilar right and left-handed tendencies of locomotion in non-direct-
ive light have been reported by Walter (’07) for planarians and
by Patten (14) for the blowfly larva. A typical example of this
behavior in bees is illustrated in figure 7, bee no. 101. In its first
trial (fig. 7, 101, a), this animal showed an average deflection of
7.11°/cm. to the left, and in the second trial (fig. 7, 101, b), a sim-
ilar deflection of 6.10°/em. Since these records were made nearly
an hour apart the left-handed tendency was not the result of a

PHOTIC REACTIONS OF HONEY-BEE 367

10]
J \
Left
a
36
ig
Left — Right Left - Right
1 \
a
Sy
Left Right
»~
b a

Fig. 7 Records of normal bees in non-directive light. In this, as in subse-
quent figures of records in non-directive light, a solid circle is used to indicate the
center of the floor of the non-directive light apparatus. a, records of the first set
of trials; b, records of the second set of trials. Bee no. 101 deflected constantly
toward the left. Bee no. 36 varied its deflection in the course of single trials.

368 DWIGHT E. MINNICH

brief, temporary condition, but was probably a more or less
permanent feature of this animal’s behavior.

The second class of animals includes those whose average de-
flections were small in both directions. The results obtained
here are attributable to either of two causes:

a. The bee varied its turning from right to left, so that on an
average, one tendency nearly or quite balanced the other.

b. The bee exhibited little or no tendency to turn either to the
right or to the left.

An example of the first type is seen in the records of bee no. 36,
figure 7. In its first set of trials (a, 1, 2) this animal turned
sometimes to the left, sometimes to the right, so that the result-
ant average deflection was but 0.79°/cm. to the left. Similarly
in the second set of trails (6, 1, 2), the average deflection amounted
to only 1.94°/em. to the right. The second type of this class is
illustrated by bee no. 134, figure 8. This animal showed no pro-
nounced tendency to turn either to the right or left. The aver-
age deflection for each set of records was, therefore, small, being
only 1.52°/cem. to the left for the first set (a, 1, 2, 3) and 1.22°/cm.
to the left for the second set (6, 1, 2, 3, 4).

In the third class of bees are to be found those which, although
they exhibited fairly uniform behavior in a single set of trials,
varied widely in different sets. For example, bee no. 82, in its
first record (fig. 8, 82, a) showed a pronounced deflection which
averaged 5.81°/cm. to the left. In its second set of trials (fig.
8, 82, 6, 1, 2, 3, 4), on the contrary, it showed little tendency to
turn, and the average deflection was but 0.65°/cem. to the left.
An even more striking case of variation, however, was afforded
by bee no. 63. In a single record of fifty-three seconds’ duration
(fig. 8, 63, a) this animal deflected, on the average, 5.58°/em. to
the left. Approximately two hours later, in a record of sixty
seconds’ duration (fig. 8, 63, b), the same animal exhibited an
even greater average deflection in the opposite direction, viz.,
7.50°/em. to the right. The range of variation presented by.
these two records is no less than 13.08°/em.

In a uniform, non-directive light field, therefore, many bees
exhibit a fairly constant tendency to turn toward a given side,

PHOTIC REACTIONS OF HONEY-BEE 369

ah S
a EAN

/ Left

134

a

Left

*

a b

Fig. 8 Records of normal bees in non-directive light. a, records of the first
set of trials; b, records of the second set of trials. Bee no. 134 exhibited little
tendency to deflect in either direction. Bees nos. 82 and 63 varied widely in their
average deflections in the two sets of trials.

370 DWIGHT £. MINNICH

others display little or no such tendency, while still others vary
widely in their deflections from time to time. Since the animal
moves in a uniform environment, the conspicuous asymmetry
of response so frequently noted must be attributed to internal
factors. Such factors are, for the most part, probably quite in-
dependent of light. A more detailed discussion of these will be
presented in a subsequent section of this paper.

4. Total darkness

If internal factors are responsible for the asymmetric responses
of bees in non-directive illumination, a similar behavior should
be exhibited in the total absence of photic stimulation. Such
was indeed the case. Animals creeping on smoked paper, in
total darkness, showed the same conspicuous tendencies to loop
and turn as did animals in non-directive light (fig. 16). The
data here referred to were taken in connection with experiments
conducted for a different purpose. They are, therefore, not
sufficiently extensive to establish more than a similarity to the
behavior exhibited in non-directive light.

Responses essentially like those of bees in total darkness have
also been described by Pouchet (’72) for the larvae of Lucilia
caesar, Davenport (’97) for the amoeba, and Frandsen (’01) for
the garden slug Limax. Frandsen’s observations in particular
bear a striking resemblance to those which I have just described
for the honey-bee in non-directive light. Thus he found that
while most of his animals looped in a fairly constant fashion to
the right or left, a few were extremely variable, while still a few
others moved in rather straight courses. The responses of creep-
ing bees in the total absence of photic stimulation are, therefore,
very similar to those observed for other animals under the same
conditions.

6. Summary

In the preceding pages certain responses of normal bees have
been described in considerable detail, but only as a prerequisite
to an adequate understanding of the behavior of the animals

PHOTIC REACTIONS OF HONEY-BEE 371

when one eye is blackened. The features of behavior which are
important in this connection may be summarized as follows:

1. In the honey-bee, light tends to induce activity; darkness,
to inhibit it. This response is dependent upon the continuous
action of photic stimulation.

2. Isolated worker bees in an active condition exhibit strong
" positive phototropism when flying or creeping. Temporary sup-
pressions of this response may occur, however.

3. Normal bees when creeping in non-directive light usually
exhibit pronounced asymmetrical responses of constant or vari-
able index. Since essentially the same responses occur in total
darkness they are not fundamentally dependent upon photic
stimulation. They are probably, therefore, conditioned largely
by internal factors.

VI. BEHAVIOR OF BEES WITH ONE EYE BLACKENED
1. Directive light

The previous investigations of circus movements have pointed
unmistakably to the generality of these responses among photo-
tropic arthropods. Positive animals with one eye covered tend
to circle toward the functional eye; negative animals, under the
same conditions, tend to circle away from the functional eye.
The honey-bee exhibits a striking positive phototropism. When
one eye is blackened, therefore, we should expect the bee to circle
toward the remaining functional eye. Such is indeed the case,
as Axenfeld (’99, p. 374) has previously shown.

In my own experiments, bees thus operated upon were no
longer able to creep in a straight course toward a source of il-
lumination. Instead, their progress thither was marked by re-
peated loops. If the right eye was blackened, the bee looped to
the left; if the left eye was blackened, it looped to the right.
Moreover, it was possible by blackening one eye, then removing
the black and blacking the other eye, to cause a single individual
to perform circus movements first in one direction, then in the
opposite direction.

372 DWIGHT E. MINNICH

The above experiment was carried out on five bees. In gen-
eral, all of these animals looped more or less markedly toward the
functional eye as they crept toward the light source. This tend-
ency, moreover, was not confined to the period immediately
subsequent to the operation of blackening the eye, as the experi-
ment clearly demonstrates. The first records of these bees with
their left eyes blackened were taken in the evening between 6
and 7 p.m. No further tests were made until the following day
at 11:30 am. Yet the behavior at the end of this seventeen-
hour period was practically the same as it had been before. One
bee, it is true, showed considerable improvement. In the other
four animals, however, the two sets of records were indistinguish-
able. In the absence of experience, therefore, the performance
of circus movements remains a permanent feature of behavior.

Of the five bees tested, the most pronounced and uniform exhi-
bition of circus movements was displayed by bee no. 5. Its’
records are almost diagrammatic in their close approximation to
the theoretical expectation. Records of this animal are repro-
duced in figure 9.

Not all of these animals, however, yielded such striking results.
Some individuals were found which manifested little or no tend-
ency to deviate toward the functional eye, except in the area
immediately beneath the lamp, where the illumination was es-
sentially non-directive. Thus, bee no. 4, with its right eye black-
ened, circled toward the left in the usual manner. But a few
hours later, when the black had been removed from the right
eye and the left eye painted over, it exhibited little or no tend-
ency to circle toward the right (fig. 10, B). The explanation
at once suggests itself, that in such cases the eye was imperfectly
covered, and hence not absolutely free from stimulation. This
may be correct. As will be shown later, however, there are also
a variety of other circumstances which might account for such
behavior.

The tendency to circle toward the blackened eye was not fre-
quently encountered in the reactions of bees to directive light.
No instance of it occurred in the experiment described above, al-
though it was occasionally met with in other experiments. A

PHOTIC REACTIONS OF HONEY-BEE 373

/ | @

It

Normal Right Eye Black.

Left Eye Black

Normal

Left Eye Black

\\ Rt yy OW

Fig. 9 Consecutive records of a bee in directive light, showing the effect of
blackening first one eye, then the other.

THE JOURNAL OF EXPERIMENTAL ZOGLOGY, VOL. 29, NO. 3

374 DWIGHT E. MINNICH

single record of this kind is shown in figure 10, A. This was ob-
tained from an animal which subsequently became wholly unre-
active. Its aberrant tendencies may, therefore, have been due
to an abnormal condition. In any case it is significant that, al-
though the bee looped toward the covered eye, yet it progressed
toward the light source. Consequently, this was not a case of

reversal of phototropism.
Instances somewhat similar to the one last mentioned have

been described by Dolley (’16, p. 373) for the butterfly Vanessa.

i i" ir

| \U [2

Fig. 10 A. Record of a bee in directive light, showing loops toward the
blackened eye. B. Two records of a bee in directive light which showed no
deflection, although the left eye was blackened.

Although positive to light, this insect with one eye blackened
occasionally turned toward the covered eye instead of toward the
functional eye. Possibly results of this sort are to be attributed
to the effect of contact stimulus afforded by the covering of the
eye, as indicated by Dolley (’16, pp. 394-399). This will be dis-
cussed more fully in a subsequent portion of the paper.

2. Non-directive light

a. Amount of turning. In non-directive light, bees with one eye
blackened tended, in general, to turn more or less pronouncedly
toward the functional eye. As was to be expected, the course

PHOTIC REACTIONS OF HONEY-BEE 375

taken by the animals under these conditions assumed no specific
direction. They either continued to circle in a fairly limited
area or proceeded in a looping fashion in any direction whatever.
The variability of this response, moreover, was much greater
than in the case of the response to directive light. Thus, a num-
ber of animals circled almost continuously toward the covered
eye in non-directive light, while still others varied, circling some-
times toward the covered eye, sometimes toward the functional
eye. This was doubtless true for much the same reasons that
normal bees also exhibited a greater variability of response in
non-directive light.

Circus movements attendant upon the elimination of one pho-
toreceptor undoubtedly represent the orienting process of an
asymmetric animal. The specific photic stimulus, therefore,
which produces these reactions must be identical with that which
effects orientation in the normal animal. Whatever the nature
of this stimulus be, moreover, it is afforded by both directive
and non-directive light, since circus movements occur in either
‘situation. What is the nature of this orienting stimulus? Per-
haps the best method of demonstrating the dependence of a par-
ticular response upon a certain stimulus is to show that the in-
tensity of the response varies with the intensity of the stimulus in
question. It seemed possible to attack this problem, therefore,
through a study of the relationship existent between the amount
of turning displayed by an animal with one eye blackened and
the intensity of the illumination to which it was subjected.

Non-directive illumination was chosen in preference to direc-
tive illumination because of the simpler experimental conditions
which the former affords. In directive light, every movement
of the entire animal is accompanied by more or less complicated
changes not only in the intensity of the stimulation received, but
also in the area of the eye stimulated. Asan animal with one
eye covered moves toward a light source, the stimulation of the
functional eye steadily increases. As it loops toward this eye,
however, this steadily increasing stimulus is subjected to rapid
and transitory fluctuations. When the animal begins to loop,
the functional eye is first turned away from the light, resulting

376 DWIGHT E. MINNICH

in a rapid decrease of photic stimulation. As the loop is com-
pleted, the photoreceptor in turn experiences an increase in
stimulation. In non-directive illumination such as was employed
in the present experiments, however, these complications are
largely avoided. Photic stimulation here is maintained at a
fairly uniform and constant intensity over the entire surface of
the compound eye.

Two slightly different types of experiment were performed.
The procedure in the first type was as follows. Bees were col-
lected from flowers in the morning between 8 and 10 o’clock,
brought into the laboratory and prepared for experimentation.
One and two hours later, respectively, they weré given single
trials in the directive light area. On a basis of these records,
individuals of abnormal tendencies were discarded, and those evinc-
ing the greatest accuracy of orientation were selected.

An hour or so later, the selected bees were tested in non-
directive light of 957 mc. Two sets of records, about one hour
apart, were made of each animal. Each set was composed of
one to several records, the aggregate duration of which, in gen-
eral, was between thirty and sixty seconds. An examination of
the records showed clearly whether the individual was normally
right-handed, left-handed, or variable in its deflection in non-
directive light. These results determined which eye should be
blackened. If, for example, a bee normally circled to the right,
the right eye was covered. Whatever influence was exerted by
photic stimulation, therefore, would tend to force the animal
toward the left. In this manner, respohses which might other-
wise have been mistakenly attributed to photic stimulation were
to some extent eliminated.

The operations of blackening the eye were carried out in the
late afternoon of the first day of experimentation, in accordance
with the technic previously described. On the following morn-
ing, before resuming experimentation, it was not infrequently
necessary to discard a few additional animals either because of
extreme weakness or occasionally death as a result of the operation.

The majority of bees usually appeared quite normal, however,
and were subjected to several series of trials in non-directive

PHOTIC REACTIONS OF HONEY-BEE 377

light. Throughout a single series of consecutive trials, or, as I
shall call it, a determination, one intensity of light only was
employed. But in the total number of determinations the more
intense illumination of 957 me. and the less intense of 24 mc. were
used an equal number of times. The animal to be tested was first
removed from the dark box and exposed from half a minute to
several minutes in the intensity of light in which it was to be
tried. This was usually sufficient to activate the animal thor-
oughly, and several records were then made in the non-directive
light chamber. In case the bee failed to respond to photic acti-
vation, recourse was had to mechanical stimulation. The cage
was tapped or even shaken fairly vigorously until locomotion
was induced. This procedure seldom failed to elicit activity.
When it did fail, it was usually necessary to discard the animal
altogether.

The number and duration of the records comprising a single
series or determination varied widely even in the same animal.
If the bee quickly encountered the side wall of the light chamber,
records were short, and a number had to be taken. If, on the
contrary, the animal kept well toward the center of the floor of
the apparatus, one or two records were quite sufficient. In cases
of great variability of response or unusual departures from the
general, expected behavior, additional trials were made, on the
assumption that a greater number would more accurately ex-
press the average tendency of the animal. Single trials seldom
exceeded thirty seconds, and were often much shorter. Occa-
sionally, however, records of forty-five seconds, sixty seconds,
or even slightly greater durations were taken. The aggregate
duration of the trials comprising a single determination, for one
intensity of light, was usually in the neighborhood of thirty or
sixty or ninety seconds. The adoption of any more uniform
period for all animals, at all times, was quite impossible.

Upon completion of a series of trials in one intensity of light,
the bee was returned to the dark box. Here it was allowed to
remain for a period of about fifteen minutes to one hour. In the
earlier experiments the longer period was practiced ; in subsequent
experiments, the shorter. After this period in the dark, the ani-

378 DWIGHT E. MINNICH

mal was subjected to a second set of trials of the same aggregate
duration as the first, but in the other of the two light intensities.
The order in which the two intensities of illumination were em-
ployed was varied from time to time. Sometimes the first de-
termination was made in the more intense light; the second, in the
less intense. Sometimes the reverse order was observed.

A single series of records in one intensity of non-directive light
together with the corresponding series in the other intensity con-
stitute what I shall term a pair of determinations. The protocol
of such a pair of determinations on bee no. 42 is given in table 3.
Four or five pairs of determinations were usually made on each in-
dividual of an experiment in the course of a day, beginning

TABLE 3
DETERMINATION FOR NON-DIRECTIVE LIGHT DETERMINATION FOR NON-DIRECTIVE LIGHT
or 24 Mc. , oF 957 Mc.
N i ,
winhiee of Hour of record D uration of ene of Hour of record che of
seconds seconds
4 1:47 p.m 30 1 1:32 p.m. 31
5 1:473 p.m. 30 2 1:322 p.m. 30
6 1:48 p.m -30 3 1:334 p.m. 30
id Boo) | ee ee 90 91

between 8 and 9 o’clock in the morning and concluding between 4
and 5 in the afternoon. The bees often seemed to become slug-
gish in the late afternoon. Whether this was due to fatigue or a
natural rhythm of activity from day to night, I am unable to say.
This phenomenon, however, led me to abandon any attempt to
continue experimentation much after 5 o’clock.

On the third and concluding day of the experiment, the scheme
of the second day was again carried out as far as possible. Bees
usually survived the first two days of experimentation, and in
case they did not, the data on them were discarded. A nianbes
of individuals, however, failed to survive in fit condition for the
trials of the third day, and still others had to be discarded in the
course of the day, although in both cases the results were counted.

PHOTIC REACTIONS OF HONEY-BEE 379

Some of the more vigorous animals survived not only a third day
of experimentation, but lived on for three or four days, and in a
few instances even longer. Although no further trials were made
with such bees, they were kept and, as far as possible, records of
their subsequent longevity taken.

Having described the first type of non-directive light experi-
ment in considerable detail, the second type may be described
very briefly. It differed from the first only in the method of
making pairs of determinations. In this case, the two determi-
nations of a pair were made during the same period of time,

TABLE 4
DETERMINATION FOR NON-DIRECTIVE LIGHT DETERMINATION FOR NON-DIRECTIVE LIGHT
OF 24 Mc. oF 957 mc.
Number of Duration of Number of Durati f
record Hour of record record record Hour of record euoed
seconds seconds
1 1:41 p.m. 30
2 1:43 p.m. il
3 1:48 p.m. 44
4 1:51 p.m. 23
5 1:53 p.m. 40
6 1:56 p.m. 30
7 1:59 p.m. 30
TotalStecscssa4 ayers <0 oe 104 104

instead of an appreciable interval apart. The bee was first tested
in one intensity of light, then within a minute or so in the other
intensity, then again in the first, and so on until a series of one to
five records had been completed for each intensity. Care was
exercised, however, even with this rapid alternation of intensi-
ties, always to expose the animal for thirty to sixty seconds in a
given intensity before subjecting it to a trialin the same. The
following protocol from bee no. 83 (table 4) will illustrate this
method of making determinations.

In both types of experiment, there were obtained for each bee
a number of pairs of determinations, usually four to ten, depend-
ing upon the longevity of the individual. The records of each

380 DWIGHT E. MINNICH

determination have been computed collectively in the manner
already described. Single values have thus been derived which
express the average deflection, or tendency to turn, exhibited by
the animal in each determination. When the turning was chiefly
toward the blackened eye, the sign of these values is negative;
when chiefly toward the functional eye, it is positive. If, now,
the value of each determination in 24 me. light be subtracted
from the corresponding one in 957 me. light, differences will be
obtained which should answer conclusively the question of rela-
tionship between the amount of turning and the intensity of
photic stimulation.

The differences obtained in the manner just described I shall
designate as d._ A given value of d may be negative or positive.
If it be negative, it signifies one of the two following possibilities:

1. The bee turned more toward the blackened eye in an illumina-
tion of 957 me. than it did in one of 24 me.

For example, in the second pair of determinations on bee no.
32 (table 2),

957 me. 24 me.
—13.28°/em. — (—9.22°/em.) = —4.06°/em.

2. The bee turned less toward the functional eye in an illumi-
nation of 957 mc. than it did in one of 24 me.
For example in the second pair of determinations on bee no. 23,

957 me. 24 me.
+6.44°/em. — (+8.92°/em.) = —2.48°/em.

If, however, the value of d be positive, it signifies one of the
two following possibilities:

1. The bee turned less toward the blackened eye in an illumina-
tion of 957 mc. than wt did in one of 24 me.

For example, in the first pair of determinations on bee no. 31,

957 me. 24 me.
—3.87°/em. — (—7.14°/em.) = +3.27°/em.

2. The bee turned more toward the functional eye in an illumi-
nation of 957 me. than in one of 24 me.

PHOTIC REACTIONS OF HONEY-BEE 381

For example, in the first pair of determinations on bee no. 21,

957 me. 24 mc.
+29.41°/em. — (+15.84°/em.) = +13.57°/em.

If the great majority of d values are of the first category, viz.,
negative, we may conclude that the animal experiences a greater
impulse to turn toward the functional eye in an illumination of
24 me. than it does in one of 957 me. If equal numbers of nega-
tive and positive values occur, there is no relation between the
intensities of photic stimulation employed and the amount of
turning. If, however, d is generally positive, we may conclude
that the tendency to turn toward the functional eye increases
if the intensity of photic stimulation is sufficiently increased.

Experimentation soon demonstrated that the only satisfactory
solution of the problem was to be had through a statistical treat-
ment of large numbers of data. Even the more constant animals
often varied widely from one pair of determinations to another
without any apparent external cause. Therefore, a large num-
ber of bees were experimented upon and each individual was sub-
jected to many tests, the averages of which were relied upon to
indicate the general trend of behavior. In table 2 (appendix) are
presented the results obtained from a careful measurement and
computation of over two thousand records taken on fifty-two
bees. On some individuals as few as sixteen records were taken;
on others as many as seventy-four. This difference was due in
part to varying longevity of individuals and in part to the fact
that more favorable animals were frequently experimented with
longer than less favorable ones. The determinations of approxi-
mately the first half of the animals were made on the plan of the:
first type of experiment, while the remainder were carried out
according to the scheme used in the second type.

From the figures presented in columns F and G of table 2,
it is evident at once that there is a marked preponderance of
the positive d values over the negative. The ratio of the two is
strikingly shown in the frequency polygon (fig. 11) Since the
number of d values varied considerably with the individual, due

382 DWIGHT E. MINNICH

to the causes noted above, I have included in the polygon only
the first four values for each bee, thus giving equal weight to
every animal. Of the total two hundred and seven*® values rep-
resented in the polygon, 81.16 per cent are positive, whereas:
only 18.84 per cent are negative, a ratio of over 4 to 1.

[42

18.84% 81.16%

26 | 26

yt]

Degrees per cm.
Fig. 11 Frequency polygon of the first four d values of fifty-two bees. The

negative values are represented by the shaded areas; th iti
sical ; the positive values, by the

®In the case of one bee it was possible to include
of only th
because of a missing record. See Table 2 (Appendix), hee goes

PHOTIC REACTIONS OF HONEY-BEE 383

The objection might be raised that although the majority of
values of d are positive, a number of them are too small to be of
any significance. It is true that differences of the order of 1°/cm.

-or less might easily be attributed to slight errors in tracing the
course of a bee. Errors in recording, however, are as likely to
occur in one direction as the other. Such is not the case with
these small values. The class of d values betwen 0 and —2°/cm.
contains but fifteen, while the class of 0 to +2°/cm. numbers
twenty-nine—nearly twice as many.

Moreover, the mode of the curve, +2°/cm. to +4°/em., lies
well beyond these small values. Differences of this magnitude —
are readily detected in the records of bees which circled constantly
toward the functional eye, as the pair of determinations in figure
12 demonstrate. Each record shown in the figure was of exactly
thirty seconds’ duration. The first two were taken three min-
utes apart in 24 me. illumination, while the third and fourth
were taken about twenty minutes later in 957 me. illumination,
one minute apart. The value of d in this case is +2.98°/em.—
about the average modal value.

In bees exhibiting considerable variation in their deflections,
however, d values, or of the modal class of even greater magni-
tude, are not so easily recognized without the accompanying fig-
ures. To illustrate this, I have selected a pair of determinations
(fig. 13) approximating the mean value of the frequency polygon,
which is +4.35°/em. As attested by the data given in connec-
tion with the figure, this animal was extremely variable in its
direction of turning. All four records were taken in the brief
period of eight minutes, nos. 1 and 2 being of twenty-eight sec-
onds’ duration each; nos. 3 and 4, of thirty seconds. The value
of dis +4.09°/cm.—a fact which does not become apparent until
the records are submitted to a careful scrutiny.

The data presented in table 2 and figure 11 show clearly that
bees with one eye blackened tend to turn more toward the func-
tional eye in a non-directive illumination of 957 mc. than they
do in one of 24 mec. The validity of this conclusion is confirmed
by still another line of evidence. A certain number of animals
were found to exhibit a very constant tendency to turn toward

384 DWIGHT E. MINNICH

the functional eye, which was always much more pronounced in
the intense than in the weak illumination. In other words, these
individuals always yielded positive values of d of rather high mag-
nitude. Bees nos. 73, 83, 95, 105, and to a lesser extent numer-
ous others afforded striking examples of such behavior. These

24 me. \
;
A 4 ;
= @
;

Fig. 12 A pair of determinations of bee no. 42, left eye black, non-directive
light.“ The records are numbered in the order in which they were taken.

957 me,

24 me. Light 9657 me, Light
Number +Degrees —Degrees ee ais +Deerees — Degrees
vecord turned turned record turned turned
1 900 0 3 1440 0
2 945 0 4 1485 0
Average deflection, +9.49° /em. Average deflection, +12.47°/cm.

d = +2.98°/cm.

animals were all thoroughly vigorous individuals, surviving not
only the three days of experimentation, but living on for at least
two days thereafter. Two of these bees, in fact, survived no less
than four days after the conclusion of the experiment.

In figures 14 and 15 are shown pairs of determinations from
two of these animals. The eight records of bee no. 73 (fig. 14)
were taken in the course of 28; minutes, while the six records of

PHOTIC REACTIONS OF HONEY-BEE 385

24 mc.
1
—
2
957 me.
ae os
. “—
e
4 =

/

! 3

Fig. 13 A pair of determinations of bee no. 123, left eye black, non-directive
light. The records are numbered in the order in which they were taken.

24 me. Light 967 mc. Light
see +Degrees — Degrees ere Mer +Degrees . —Degrees
#enord turned turned tecordl turned turned
2 495 1170 1 630 0
4 270 450 3 225 720
Average deflection, —3.53° /em. Average deflection, +0.56°/cm.

d = +4.09° /em.

386 DWIGHT E. MINNICH

24 mc.

ie)

5 7
957 mc.
@
e a
2 4 6 8
Fig. 14 A pair of determinations of bee no. 73, left eye black, non-directive
light. The records are numbered in the order in which they were taken.
24 me. Light 957 me. Light
Number +Deegrees — Degrees Buber +Degrees —Degrees
Seeard| turned turned record turned turned
1 360 90 2 1485 0
3 45 0 4 990 0
5 2115 0 6 3510 0
7 2070 225 8 4005 0
Average deflection, +6.07°/cm.

Average deflection, +13.82° /em.
d = +7.75° /em.

PHOTIC REACTIONS OF HONEY-BEE 387

bee no. 105 (fig. 15) required only fifteen minutes. In both figures,
each record of the top row is of exactly the same duration as the
corresponding one of the lower row, except records 1 and 2 of
bee no. 73, which differ by one second. It would be difficult to

24 mc.
e) &
Se,
a mc.
Co EF &

Fig. 15 A pair of determinations of bee no. 105, right eye black, non-directive
light. The records are numbered in the order in which they were taken.

24 me. Light 957 me. Light
sales abe +Degrees — Degrees Dineihe -+Degrees — Degrees
record turned turned Feoord turned turned
1 1260 45 2 1935 0
3 855 0 4 2430 0
5 1305 90 6 2520 0
Average deflection, +6.74° /cm. Average deflection, +14.83°/cm.
“d= +8.09°/em.

imagine more conclusive results than those afforded by these two
bees. ,

It might be supposed that animals would be found which would
exhibit the opposite of the condition just described. Such, how-
ever, was not the case. I failed to find any individuals which
continually circled more toward the functional eye in an illumi-

388 DWIGHT E. MINNICH

nation of 24 me. than they did in one of 957 mc. Bees presenting
a number of negative d values, such as nos. 22, 25, 34, 41, 43, 55,
56, 62, 66, 85, 126, and 135, with one exception, showed an equal
or greater number of positive values. The exception noted was
bee no. 56. Three of the four pairs of determinations obtained
on this animal not only yielded negative differences, but differ-
ences of large magnitude as well. Bee no. 56, like a number of
other individuals presenting a considerable number of negative
d values, varied considerably in its behavior and turned chiefly
toward the blackened eye. How far the disturbing factors thus
evidenced account for the results is not absolutely certain, since
a number of bees of apparently similar tendencies yielded posi-
tive values of d. Certainly, however, there are a number of
factors, particularly in the type of experiment under considera-
tion, which do interfere with the effect of photic stimulation.
Some of these serve to intensify the response, while others tend to:
counteract or even completely annul it. Without attempting to:
minimize the significance of these negative data in the least, I
believe some of them, probably all of them, find their explana-
tion in such factors. If this be correct, the negative results ob-
tained lie well: within the range of variation which might be
expected in experimental work of this sort. A more extended
discussion of the factors responsible for variability of behavior in
the present experiments is presented in the next section of this
paper.

The evidence in general, therefore, seems to warrant the con-
clusion that bees with one eye blackened tend to turn more toward
the functional eye in an illumination of 957 me. than in one of
24mc. This tendency may result in the animal’s actually turn-
ing more toward the functional eye, or in its turning less toward
the covered eye, depending upon the idiosyncrasies of the indi-
vidual. In either case, however, with increased photic stimula-
tion, there is an increased tendency toward the functional eye.
The nature of the stimulus afforded by the apparatus employed
was continuous and of almost uniform intensity, and since the
ey eae ee vary with the intensity of

) 8 pendent upon it. These con-

PHOTIC REACTIONS OF HONEY-BEE 389

clusions are the exact antitheses of those reached by Dolley (’16)
in his work on Vanessa. He says (p. 417): ‘“‘Vanessas with one
eye blackened do not move in smaller circles in strong light than
they do in weak light, unless it is extremely low. On the con-
trary, the evidence seems to indicate that the stronger the light
is the larger the circles are. These results also are not in har-
mony with those demanded by the ‘continuous action theory.’ ”’
I shall return later to a more complete consideration of the theo-
retical significance of the results afforded by the honey-bee.

b. Rate of locomotion. Although bees with one eye blackened
tend to turn more toward the functional eye in a non-directive
light of 957 mc. than they do in one of 24 mc., there is no differ-
ence in the rate of locomotion in the two intensities. In table 5
are given the average velocities of thirty-four bees for each of
the two light intensities employed. These figures show a con-
siderable range of individual variation, from as low as 3.49 cm.
per second to as high as 6.77 cm. per second. There is, however,
no consistent difference which might be attributed to the effect of
light. Eighteen of the animals showed a greater velocity in 957
me. illumination; sixteen, in 24 me. illumination. Unilateral
photic stimulation of the intensities employed is, therefore,
without effect upon the rate of locomotion.

3. Summary

1. Bees with-one eye blackened usually loop toward the func-
tional eye ‘as they creep toward a source of light. Some indi-
viduals are encountered however, which display little tendency to
loop, and occasionally an animal will be found which loops toward
the covered eye. In the absence of experience, the tendency to
loop toward the functional eye remains a permanent feature of
behavior.

2. In non-directive light, bees with one eye blackened gener-
ally circle toward the functional eye, although a number are
found which circle more or less toward the covered eye.

3. In a uniform non-directive illumination of 957 mce., the
tendency to turn toward the functional eye is greater than it is
in a similar illumination of 24 me.

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, No. 3

390 DWIGHT E. MINNICH

4. Since the amount of turning varies directly with the intensity
of continuous photic stimulation, the turning is produced by this
stimulus.

5. Unilateral photic stimulation of the intensities employed
has no effect upon the rate of locomotion.

TABLE 5

A B c D

NUMBER OF BEE Sica yeas stata SEC, Brey cee ae SEC. aera
a 6.10 6.22 +0.12
22 5.10 5.12 +0.02
23 5.02 5.03 +0.01
a 4.95 : 5.18 +0.23
25 4.67 4.53 —0.14
31 3.77 4.28 +0.46
32 4,20 4.74 +0.54
33 5.27 5.19 —0.08
34 4.78 4.99 +0.21
be ed 3.63 +0.14
41 4.45 4.29 —0.16
42 4.76 4.30 —0.46
43 5.59 5.76 40.17
44 4.94 4.90 —0.04
45 4.36 4.99 +0.63
51 4.51 4.40 0.11
52 5.09 5.08 0.01
53 6.77 6.53 0.24
. 54 5.53 5.17 0.36
55 6.09 5.21 , 0.88
56 5.32 5.53 +0.21
62 4.82 459 ¢ wa 58
- 5.80 5.72 ~0.08
5.10 515 Feces
68 5.14 5.34 40.20
72 4.69 4.87 40.18
n ae 5.44 +0.47
7 4.26 3.99 0.97
81 4.41 4.32 0.09
pe 5.25 "5.29 +0.04
88 5.22 4.93 tie
- 4.91 4.79 Sie
91 4.48 464. é ae
92 4.49 i +0.16
es +0,02

PHOTIC REACTIONS OF HONEY-BEE 391

VII. VARIABILITY OF PHOTIC RESPONSE

The honey-bee is remarkably constant in the strong positive
phototropism which it evinces. The course of individuals creep-
ing in directive light is a straight path toward the source. Yet,
as has been shown, occasional departures from this behavior do
occur. In non-directive light, moreover, the responses of normal
bees are frequently extremely variable. The animal may turn
markedly toward a given side in one trial, and in the next, turn
quite as markedly toward the opposite side. Again, the direc-
tion of turning may be completely changed several times in the
course of a single trial.

It is not surprising, therefore, that bees with one eye blackened
also exhibit considerable variability of response in both directive
and non-directive illumination. In non-directive light particu-
larly, there were a number of cases in which animals turned little
or not at all toward the functional eye, while there were still
others in which they circled chiefly toward the covered eye. In
fact, over 25 per cent of the first four pairs of determinations on
the fifty-two bees, when averaged, gave negative values. These
departures from the more usual tendency, to turn toward the
functional eye, sometimes characterized the entire behavior of
an individual; again, they appeared only spasmodically.

Thinking that some of the results above mentioned might be
attributed to a loss of phototropism, either permanent or extend-
ing over a considerable interval of time, I frequently subjected the
animals exhibiting them to one or more immediate trials in direc-
tive light. This, however, failed to show anything which might
be construed as a loss of phototropism. The variations of
response noted, therefore, must be referred to external and internal
factors which are capable of modifying, in a more or less profound
way, the dominating effect of unilateral photic stimulation.
Such factors are of two sorts, those which are continuously effec-
tive and those which are not continuously effective, but fluctuate
from time to time. Both types played so considerable a réle in
the experiments previously described, that I have felt they mer-
ited the somewhat extended analysis presented in the following,

pages.

392 DWIGHT E. MINNICH

1. Continuous factors

a. Temperature and humidity. Of the continuously operative
factors, none are more important than the general conditions of
temperature and humidity. These profoundly affect the activity
of bees. MelIndoo (’14, p. 279) says: “Climatic conditions per-
ceptibly affect the activity of bees. When it is extremely warm,
they are most active and are rarely quiet even for a few seconds.
When it is moderately warm, they are less restless, and when
rather cool, bees do not move freely.” Again he says: ‘‘ During
cool weather their movements are quite sluggish, and when the
humidity is high they are much less active and respond to vari-
ous odors more slowly than when there is low humidity.”

Precisely the same effects were noted in the present experi-
ments. So serious did they become on several occasions that the
' experiment had to be abandoned. On cool, damp days bees
were apt to be quite unreactive, and prolonged exposure to light
often failed to induce locomotion. Considerable mechanical stim-
ulation might call forth creeping, but it was of desultory kind
and was apparently unaffected by photic stimulation. There can
be no doubt, therefore, that general weather conditions consid-
erably affect the behavior of bees toward light. Since some
experiments were continued under less favorable weather con-
ditions, it is quite probable that they account for some of the
aberrancies observed.

b. After-effects. In making quantitative determinations in
non-directive light, trials were frequently made in the two inten-
sities. in rapid succession. Although the bee was always exposed
for at least thirty seconds to a given intensity before making a
test, there still existed the possibility that an after effect of the first
intensity might influence the behavior of the animal in the sec-
ond. Thus Herms (711, p. 215) has demonstrated an after-effect
of photic stimulation in the blow-fly larva, which may manifest
itself in the continued orientation of the animal for as much as
fifteen to twenty seconds after the cessation of the stimulus.
That such is not the case for bees, however, is very clearly dem-
-onstrated by the following experiment.

PHOTIC REACTIONS OF HONEY-BEE 393

Normal bees were allowed to creep on a strip of smoked paper
toward the 80-c.p. incandescent lamp. When, after creeping a
distance of about 60 cm., the bee reached a point 40 cm. from the
source of light, the lamp was extinguished. Not only was the
current turned off, but a screen was simultaneously placed before
the lamp, so that even the slight after-glow of the filaments was
eliminated. After ten seconds of total darkness the light was
turned on and the bee removed. Two to four records were made
of each of eleven animals in this manner. In not one case did
the bee fail to lose its orientation within at most a couple of
seconds after the extinction of the light. -Often the loss of ori-
entation was almost, if not quite, simultaneous with the cessa-
tion of the stimulus. The deviation from the former orienta-
tion was sometimes marked by a pronounced tendency to turn
toward one side, with the result that the animal crept in circles
in the dark. At other times the bee merely wandered, turning
first in one direction, then another. Typical records of two ani-
mals are reproduced in figure 16. There is, therefore, no after-
effect of photic stimulation in the honey-bee, and this does not
account for any of the irregularities observed.

c. Failure to elominate photoreceptor. The difficulties in manipu-
lating bees necessitate relying upon a single operation to elimi-
nate completely the function of the compound eye. Although in
this operation great care was exercised to cover the eye com-
pletely with a heavy coat of paint, there isa possibility that in a few
cases this was not accomplished. Moreover, from the moment
the animal began to recover from the anaesthetic, the covered
eye was repeatedly subjected to vigorous scrapings by the front
leg of the same side. While the examination of a number of
animals after experimentation showed that this seldom resulted
in a removal of any of the eye covering, it probably succeeded in
doing so in a few cases. Occasionally, also, the varnish cracked
somewhat on drying. These unavoidable failures to keep the
compound eye entirely free of light, undoubtedly modified, to a
greater or less extent, not a few of the results obtained.

Beside the failure to cover the eye, there is the possibility that
the three ocelli of the honey-bee are concerned in its photic

394 DWIGHT E. MINNICH

Fig. 16 Smoked-paper records of two normal bees creeping toward a light
source (upward in the figure). As the animals reached the line indicated by the
letter P the light was extinguished. Note the extremely rapid loss of orientation,

PHOTIC REACTIONS OF HONEY-BEE 395

behavior. In blackening the compound eye I made no attempt to
cover the ocelli, but afterward in examining the specimens used,
I found that sometimes all, sometimes only one or two, at other
times none of these organs had been covered. If the ocelli do
exercise any considerable function, therefore, there was involved
here a variable of no small magnitude.

It is also possible that in bees other portions of the body, or
even the entire integument, may be photosensitive. Photoder-
matic sensitivity is not unknown among arthropods. It has
been reported by Graber (’84) for the cockroach, by Plateau (’87)
for two species of blind myriapods, and by Stockard (’08) for the
walking-stick.

In order to find out if these several possibilities were affecting
results, I conducted several experiments with bees both eyes of
which had been carefully covered with a thick coat of ‘Jap-a-lac.’
On the morning after the operation, each bee was placed in a
separate cage in non-directive illumination of 957 mc. Although
with one or two exceptions the bees were quiet when first exposed
to the light, within fifteen minutes all had become thoroughly
active, showing clearly that they were not free from the activat-
ing effect of the light.

‘At the conclusion of the above test the same bees were individu-
ally subjected to trials in the directive light area. Here they
looped and turned in a variety of ways, some circling more or less
constantly toward a given side, not unlike bees with only one
eye blackened. Despite most devious courses, however, they
sooner or later managed to work their way to the general region
of the source of light. It is quite clear, therefore, that photore-
ception had not been entirely abolished, although both com-
pound eyes had been covered as carefully as possible.

Which of the several explanations advanced accounts for these
results, is not certain. I am disposed to believe that the failure
to eliminate the compound eyes completely was chiefly, perhaps
solely, responsible. However that may be, it is certain that in
this, as well as in other experiments, the incomplete suppression
of photic stimulation was the source of a large amount of varia-
tion in the results obtained.

396 DWIGHT E. MINNICH

d. Effect of contact stimulus. The effect of the contact stimu-
lus afforded by the blackening material on the eye and the adja-
cent parts of the head must also be recognized as a considerable
factor in modification of photic behavior. The influence of this
stimulus has been clearly demonstrated by Dolley (16, pp. 394—-
397) on Vanessa antiopa. With one eye blackened, this butter-
fly, when creeping in total darkness, turned, with few exceptions,
continuously toward the blinded eye. The tendency to circle
was often quite pronounced, and showed little or no modification
from day to day. The effect of contact stimulus on the covered
eye was, therefore, antagonistic to that produced by light on the
opposite, functional eye.

I tried experiments with the honey-bee similar to those car-
ried out by Dolley on Vanessa. Bees with one eye blackened
were allowed to creep on smoked paper in total darkness. Un-
fortunately, the trials were of such duration that the bee recrossed
its course many times. This made it quite impossible to decipher
the records, and I have not since had an opportunity to repeat the
experiments. It is not unlikely, however, that the effect of con-
tact stimulus on the eye of the bee is similar to that demonstrated
for Vanessa. If such be the case, it probably accounts for much
of the circling toward the covered eye, which was evinced by
numerous individuals particularly in non-directive light.

e. Asymmetry of the animal. As was previously pointed out,
normal bees frequently exhibited a marked tendency to turn more
or less constantly toward the right or left when creeping in non-
directive light. Such tendencies are doubtless due to a lack of
perfect symmetry on the part of the animal. The asymmetry
may be physiological; it may be anatomical. It may consist of
a differential sensitivity of the photoreceptors on the two sides
of the body, as Patten (’14, p. 259) has suggested, or it may be due
to an inequality of any two symmetrically located elements of
the neuromuscular mechanism. Under the influence of directive
light, these idiosyncracies are, as a rule, continually corrected.
In non-directive illumination or total darkness, however, they at
once assert themselves. Since the eye to be blackened was always
chosen so that the effect of photic stimulation would be opposite

PHOTIC REACTIONS OF HONEY-BEE 397

to that exerted by natural asymmetry, many failures to turn
toward the functional eye are probably thus accounted for.

f. Modifiability through experience. The work of Axenfeld,
Holmes, Brundin, and Dolley has shown that a number of ar-
thropods are able to modify their photic behavior through expe-
rience. The same is true of the honey-bee, at least in directive
light, as the following experiment shows. Each of a number of
normal bees, selected on the basis of the accuracy with which they
oriented to directive light, had one eye blackened. On the fol-
lowing day those animals which exhibited a more or less pro-
nounced tendency to loop toward the functional eye were sub-
jected to trials (twenty to twenty-five in number) in the directive
light area.

Bees which displayed little or no tendency to loop were given
several trials to ascertain if their behavior was constant, and then
discarded. These animals may have been able to modify their
behavior almost immediately, or their failure to exhibit circus
movements may have been due to an imperfect covering of the
eye, or to the effect of contact stimulus.

Of those bees which did perform circus movements, records
were taken about every ten to twenty minutes from 9 a.m. to
5 p.M., with the exception of about an hour at noon. Ten bees
were thus tested. Four of these animals displayed a steady and
marked improvement in the course of the trials. Two others
showed some improvement, although considerably less than the
first four. Two more of the ten improved for a time, only to
regress again, so that while a number of trials near the middle of
the series were somewhat modified, those at either end were
rouch alike in the number of loops performed. The last two bees
showed practically no improvement, although in one of the ani-
mals the tendency to circle was at no time very pronounced. It
is quite certain, therefore, that at least some bees are able to mod-
ify their responses to directive light through experience.

The records shown in figure 17 afford a striking example of this
modifiability. Although in its first trials the animal looped re-
peatedly as it crept toward the light, it was subsequently able to
reach the light by a nearly straight course. This animal, how-

398 DWIGHT E. MINNICH

O \ °

; )
ce
OLr y O O fe) )

rw oO x [/ |

(| Lz
\

bled Md.

Fig. 17 Records of a bee with the left eye blackened, in directive light, show-
ing modifiability of behavior through experience. Alternate records from a
series of twenty-six are shown in the figure.

PHOTIC REACTIONS OF HONEY-BEE 399

ever, as well as the others, usually circled again toward the func-
tional eye upon reaching the non-directive region near and
directly beneath the lamp. The records shown in the figure do.
not include this region.

Dolley (’16, p. 402) states that he observed some modification
from day to day in the behavior of Vanessa in non-directive light.
The following evidence seems to indicate that the same is true,
to at least some extent, for the honey-bee also. In directive
light, individuals with one eye covered were sometimes observed.
to begin to swerve toward the functional eye, only to check them-
selves by a sharp turn in the opposite direction. Correcting
movements of this sort sometimes occurred repeatedly in a single
trial, with the result that the animal reached the source of light
by a much more direct course than it would have otherwise been
able to follow. Precisely the same sharp turns away from the
functional eye were occasionally seen in non-directive light also.
It seems probable, therefore, that modifiability through experi-
ence affects the behavior of bees in non-directive as well as in
directive light.

2. Fluctuating factors

The variables which have thus far been discussed are those
which continuously or progressively affect the behavior of bees
throughout an experiment. They probably account in a large
measure for such phenomena as the persistant turning toward
the covered eye in certain individuals or the apparent lack of any
tendency to turn at all in still others. They do not, however,
explain the many sudden changes cf behavior which were ob-
served. Such variations are dependent upon factors of behavior
which fluctuate from time to time. A few of these factors result
from environmental changes. The majority, however, arise from
changes within the organism itself.

a. External. In quantitative experiments every possible pre-
caution was exercised to keep all external factors uniform, except
the intensity of the light which was changed from trial to trial.
This, of course, was possible to a limited extent only. The
manipulation of the bees introduced varying mechanical stim-

400 DWIGHT E. MINNICH

uli which were quite unavoidable. An animal was accidentally
pressed slightly in changing it from one cage to another, or, fail-
ing to react to photic stimulation, the cage had to be shaken.
Again, in transferring a bee from the light to which it was sub-
jected for activation to the center of the non-directive light cham-
ber, it was subjected to increases and decreases of light intensity.
All of these details and endless others, collectively and individu-
ally, were undoubtedly responsible for many of the sudden
variations of behavior which occurred.

b. Internal. The chief causes of irregular variations, however,
are internal. When under constant external conditions, a bee
varies the direction of its turning several times in the course of a
single trial, the behavior must be attributed to changes within the
animal itself, the physiological states of Jennings (’06). Gener-
ally speaking, the analysis of these changing physiological states
is difficult or impossible. In several instances, however, I was
able to make a fairly certain diagnosis. I may cite several
examples.

Bee no. 147 was subjected to the usual quantitative experi-
ment in non-directive light. From the beginning this animal
exhibited a rapid, uneasy locomotion. Its entire behaviormay
best be described by the word ‘excitable.’ In the course of the
first day after the eye was blackened, five pairs of determinations
were made. In 24 me. light, the animal circled chiefly toward
the covered eye, while in 957 mc., its behavior varied from one
set of records to another.

On the following morning, the first pair of determinations was
begun at 9:49. The bee circled markedly toward the covered
eye in both intensities of light. At 12:14, a second pair of
determinations was begun. In making the first trial, the bee
rushed about its cage for some minutes before finally creeping up
into the non-directive light chamber. When it did appear, it
seemed greatly excited and crept very rapidly. As the series of
records progressed, the animal circled more and more pronouncedly
toward the functional eye, the locomotion grew more rapid, and
a continuous buzzing began. The performance of small circles
toward the functional eye in 24 me. light was surprising, for in

PHOTIC REACTIONS OF HONEY-BEE 401

all previous record sets for this intensity, the animal had shown a
more or less pronounced tendency to circle toward the covered
eye. In the course of the fourth trial in 957 me. light, the bee
had reached a state of intense excitation. Its turning became so
rapid, and the consequent circles so small, that at length the
animal tumbled over on its back. Defaecation occurred. Mean-
while it continued buzzing loudly, and, though lying on its back,
managed to whirl round and round toward the functional eye.

After the trial just described, the animal was allowed to rest for
two hours. At 2:44 and 4:10, respectively, two more pairs of
determinations were made. The bee continued to circle markedly
toward the functional eye in 957 me. light, and more or less toward
the functional eye in 24 me. light. The ‘excitement’ which had
characterized the previous trials, however, was absent, and the
animal manifested signs of weakness and exhaustion.

In the behavior of this animal there was a sudden—even vio-
lent—increase of phototropism. This was probably due to an
unusual intensification of activity. I have repeatedly observed
the close correlation between these two features of behavior in
bees. As a rule, the greater the activity, the more pronounced
is the manifestation of phototropism. The increase of activity
in this animal was produced by a state of metabolism, entailed
by a collection of faeces in the intestine. That such’ a condition
may affect the activity of bees to a marked degree is evidenced by
the following statement made by Phillips and Demuth (’14, p.
12) in connection with a study of certain hive conditions in win-
ter. ‘‘It therefore appears that the accumulation of feces (in
the intestine) acts as an irritant, causing the bees to become more
active and consequently to maintain a higher temperature.”

In several other animals defaecation occurred in the course of
a trial without being preceded by any conspicuous change of
behavior. Neither the amount voided nor the force of expulsion,
however, gave any evidence of long accumulation or intestinal
irritation in these cases. It seems reasonably certain, therefore,
that the sudden increase of phototropism exhibited by bee no.
147 was due to the accumulation of faeces in the intestine.

402 DWIGHT E. MINNICH

There were likewise certain other physiological conditions
which seemed to intensify photic reactions. Thus bees, upon first
recovering from anaesthesia, were frequently observed to creep
in very small circles toward the functional eye. Bees, which
throughout an experiment appeared physically weak, were also
apt to be more intense in their positive deflections. Examples
of this latter behavior were afforded by bees nos. 77 and 92.
Again, individuals which appeared vigorous at the beginning of
an experiment, but became weak and moribund toward the end,
generally showed a progressive increase in their circus movements.
For example, bee no. 91 circled rather strongly toward the cov-
ered eye at first. In the course of the experiment, the animal
became weak. Correspondingly, its average deflections became
more and more positive until, just before being discarded, it was
turning at the rate of +23.82°/cm. in 957 me. light.

These instances demonstrate the profound manner in which
internal factors are capable of modifying photic behavior. As a
rule, only the change in behavior is noted. The recognition of
the internal state which conditions this outward expression is
possible only in extreme cases. Nevertheless, I believe that these
internal factors were directly responsible for most of the sudden
variations which characterized the behavior of so many bees.

Thus far we have tacitly assumed that the honey-bee is a purely
reflex organism. It is not the purpose of the present paper to
discuss the mooted question of psychic powers in this animal. It
may be said, however, that the opinion advanced by Bethe (’98),
that the behavior of bees affords no evidence of psychical attri-
butes, has not met with extensive approbation. Forel (’07) and
v. Buttel-Reepen (’07), in particular, have presented consider-
able evidence to show that bees are something more than mere
reflex machines.

v. Buttel-Reepen (’07, p. 23) has shown that after bees have
been deadened with chloroform, ether, saltpeter, puffball, etc.,
their memory for location entirely disappears. Subsequently they
may again ‘learn’ the position of the hive, etc., but for the time
at least, “they have forgotten everything previously known.”
My own observations have shown that during recovery from an

PHOTIC REACTIONS OF HONEY-BEE 403

anaesthetic and in weakened or moribund conditions the photic
responses of bees become more intense. Photic behavior, how-
ever, is probably largely reflex in character. It would appear,
therefore, that the same conditions which occasion a loss of
‘memory’ or other central function and the like cause the reflex
phases of behavior to appear more boldly. In other words bees,
though fundamentally reflex, may possess certain rudiments of
higher behavior. Under the influence of narcotics and anaes-
thetics or in moribund conditions, these factors cease to affect
behavior, and the animal is reduced to a simple reflex condition.
If this be correct, we have here an important variable to account
for modifications of photic behavior.

3. Summary

The variability of respdnse displayed by bees with one eye
blackened when creeping in non-directive light is never due to a
permanent loss of phototropism or to after-effects of one inten-
sity upon trials in a second intensity. It is attributable to the
following causes:

a. Conditions of temperature and humidity.

b. Failure to eliminate completely the photoreceptors on one
side of the body.

c. Effect of contact stimulus afforded by the eye covering.

d. Natural asymmetry of individuals.

e. Modifiability through experience.

f. Mechanical stimuli attendant upon manipulation.

g. Internal factors which affect behavior variously from time
to time.

VIII. NATURE OF PHOTIC ORIENTATION

1. Theories

In recent years the photic behavior of lower animals has been
the subject of two theories, respectively known as the ‘continuous
action theory’ and the ‘change of intensity theory.’ The ‘con-
tinuous action theory,’ as its name implies, postulates a continu-
ous action of light upon the organism, orientation resulting when

404 DWIGHT E. MINNICH

such action is equal on the symmetrical photoreceptors of oppo-
site sides of the body. In its present form this theory is perhaps
best summed up by Loeb (’16, p. 259). ‘‘If a positively helio-
tropic animal is struck by light from one side, the effect on tension:
or energy production of muscles connected with this eye will be
such that an automatic turning of the head and the whole animal
towards the source of light takes place; as soon as both eyes are
illuminated equally the photochemical reaction velocity will be:
the same in both eyes, the symmetrical muscles of the body will’
work equally, and the animal will continue to move in this direc-
tion. In the case of the negatively heliotropic animal the picture
is the same except that if only one eye is illuminated the muscles:
connected with this eye will work less energetically.”

The ‘change of intensity theory,’ however, accounts for ori-
entation in an entirely different manner. According to it, the proc-
ess depends not upon the continuous action of light, but upon.
the intermittent action of rapid changes in its intensity (Jennings.
04, 706, ’09; Mast, 711). In positive organisms the effective
stimulus is assumed to be a sudden decrease of intensity on the
photoreceptor; in negative organisms, a sudden increase. A
photopositive animal, such as the honey-bee, for example, orients.
and maintains its orientation through sudden swervings away from.
the side experiencing a decrease of illumination, and orientation.
is attained when neither eye is undergoing such a decrease. A
similar explanation is applied to photonegative organisms except
that the effective stimulus for them is assumed to be an increase
of intensity.

There is thus a wide diversity in the explanations of orientation
offered by these two theories. In the concluding pages of this
paper, therefore, I propose to discuss the evidence afforded by
my own experiments, as well as that afforded by the observations
on circus movements in general, with a view to ascertaining
which of the two theories more correctly applies to the orienta-
tion of arthropods.

PHOTIC REACTIONS OF HONEY-BEE 405

2. Orientation in the honey-bee

As has been previously stated, the process involved in circus
movements must be regarded as identical in every respect with
that involved in normal orientation. The circus movement is
the orienting process. A normal creeping bee may be caused to
‘ perform circus movements without having one eye blackened,
if the light is merely moved so as to keep it constantly to one side
of the animal. Whether the eye be blackened or the light be
moved, the case isthe same. The orienting process is merely pro-
longed, and the final attainment: of orientation prevented.

The experimental data detailed in the present paper show con-
clusively that when one eye of a bee is blackened, the resulting
circus movements are produced by the continuous action of the
light upon the functional photoreceptor. In the experiments in
non-directive light, the only photic stimulation afforded was one
of constant, almost uniform intensity over the entire surface of
the eye. Under such conditions, the animals not only performed
circus movements toward the functional eye, but the amount of
turning increased with an increase in the stimulus. It is clear,
therefore, that the process of normal orientation, which is iden-
tical with that involved in the circus movement, must also be
dependent upon the continuous action of light.

The impulses arising from this stimulation are, at least in part,
transmitted to the musculature of the opposite side of the body,
since upon hemisecting the brain, the bee suffers a complete loss
of phototropism (Holmes, ’01, p. 227). Although his experi-
ments were not conclusive on the point, Holmes believed that
the result obtained was not entirely due to ‘“‘the effect of the
shock of the operation, or of incidental injury to other paths of
photic impulses.’ It must, therefore, have been due to the sev-
erance of crossed tracts or commissures which served in the trans-
mission of such impulses. There are present in the dorsocerebron
of the bee at least three commissures in more or less intimate
connection with the optic tracts (Kenyon, ’96), and it is possible
that these are the elements concerned. There is thus neurologi-
cal as well as physiological evidence for the crossed transmission

of photic impulses.

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, No, 3

406 DWIGHT E. MINNICH

The resultant effect of these impulses on the opposite side of
the body is most probably an increase in the tonus of the extensor
muscles. I have no direct evidence on this point in the case of
the honey-bee. However, Holmes (’05) and Holmes and
McGraw (13), in experiments dealing with unilateral stimulation
of photopositive insects, frequently observed that the legs on.
the side away from the stimulated eye were strongly extended,
while those on the same side exhibited a pronounced flexion.
Recently, Garrey (17) has published an account of numerous
experiments in which the same phenomenon was observed. In
such animals it is clear that orientation is effected through a
difference in the posture and not through a difference in the speed
of the legs on the two sides of the body. This conclusion is
further substantiated by the results obtained by Dolley (’17) on
Vanessa. Careful measurement of the velocity of these butter-
flies showed that they did not creep faster in a very intense
illumination than they did in a fairly weak one. From the above
observations, therefore, it is clear that in many insects orienta-
tion is effected through changes of tension in the leg muscles. As
previously stated, I have not been able to observe any constant
and pronounced difference in the muscular tension on the two
sides of the body in the honey-bee, although I have made only
casual observations in this direction. I do believe that orienta-
tion is produced-in this manner, however, and that the failure
to detect it was due to the slight degree of the tensions together
with the extreme rapidity of their execution.

This attempt to analyze the process of orientation in the honey-
bee is, of course, far from complete. Certain features of it, how-
ever, may be defined with reasonable certainty. Thus it is
clear that the stimulus regulating photic orientation is continu-
ous and not intermittent. Furthermore, it appears to be essen-
tial that at least some of the ‘impulses arising in the eye be
transmitted to the opposite side of the body, where they probably
regulate the tonus of the extensor muscles. Asfar asit is known,
therefore, the process of orientation in the honey-bee is in strict
conformity with the ‘continuous action theory.’

PHOTIC REACTIONS OF HONEY-BEE 407

8. General evidence

In experimenting with locomotor organisms, it is not an easy
matter to regulate absolutely the conditions of photic stimulation.
Thus, a photopositive animal as it moves toward the light is
acted upon continuously by the light. But it is also subjected
not only to a gradual increase of intensity with every forward
movement, but also to sudden decreases and increases with every
lateral deviation, however slight. Whether the orientation of
the organism, therefore, is effected through a continuous action
of the stimulus or only through sudden changes in its intensity
from time to time, is frequently difficult to determine with cer-
tainty. This difficulty in separating the two conditions experi-
mentally has led to much confusion in solving the problem of
orientation. Among arthropods, however, there is a growing
body of evidence tending to show that orientation is produced by
continuous photic stimulation and not by intermittent changes of
intensity.

No stronger evidence is to be found in this connection than
that afforded by the general phenomenon of circus movements.
The importance of this evidence has been repeatedly emphasized
by Parker (’03, ’07), Loeb (’06, 713), Bohn (’09 a, b), Holmes
and McGraw (’18), Garrey (717), and others. Parker (707, p.
548), in reviewing one of the earlier expositions of the ‘change of
intensity theory’ (Jennings, ’06), states the case clearly when he
says, ‘‘If the modern tropism theory were as weak as Jennings
would have us believe, the experimental evidence upon which it
rests ought easily to be explained away. Yet it has always
seemed to the reviewer that the characteristic circus movements
performed by animals immersed in a homogeneous stimulant,
but with sense organs unilaterally obstructed, are explainable
only on the basis of this theory.”

This statement is certainly justified by the facts. Circus
movements seem quite incapable of explanation in terms of the
‘change of intensity theory’ of orientation. Let us examine the
case of a photopositive arthropod, with the right eye blackened,
as it creeps toward a source of light. From experiment we know

408 DWIGHT E. MINNICH

that such an individual usually loops to the left. As it does so,
however, the functional eye experiences a pronounced decrease
of stimulation during the first half of each loop. According to
the ‘change of intensity theory,’ such decreases should result in
swerves toward the opposite side. Such, however, do not occur,
as arule. The animal, instead, completes the loop. It, there-
fore, does not respond very strongly to a decrease of intensity.
If it did, the performance of circus movements would be quite
impossible. If we assume, however, that the looping is produced
by the continuous inequality in the stimulation received by the
two eyes, the asymmetry of response becomes intelligible at once.
For, in an animal with one eye blackened, the functional eye,
even when turned farthest from the light, is the recipient of some
stimulation, whereas the covered eye receives none whatever.

It may be objected, however, that many positive arthropods
with one eye blackened are able to overcome their tendency to
circle in directive light, and that this is a response to the decrease
of intensity on the functional eye at the beginning of each loop.
Such may well be the case, as Holmes (’05, p. 345) has suggested.
This is a matter for further experiment to decide. In any case,
however, circus movements must be regarded as an established
phenomenon of general occurrence among this group of animals.
The significant thing, therefore, to an understanding of orienta-
tion is to discover what is effective in producing these reactions
rather than what is effective in modifying them.

The evidence afforded by circus movements in directive light
as to the nature of the stimulus concerned in their production is
thoroughly corroborated by the results obtained in non-directive
light. Under the conditions of non-directive illumination em-
ployed by Holmes and McGraw (’13) and by myself, an animal
is absolutely free from any pronounced or consistent changes in
the intensity of the stimulus to which it is subjected. More-
over, the experiments of Dubois (’86) on the beetle Pyrophorus
furnish a case in which there is no possibility whatever of inten-
sity changes playing a significant réle in orientation, since the
source of light is within the animal itself. Yet in all these cases
the elimination of one eye was usually followed by typical circus

PHOTIC REACTIONS OF HONEY-BEE 409

movements toward the functional eye. In the absence of signifi-
cant intensity changes, these responses must have been produced
through the continuous action of light. The correctness of this
conclusion is further attested by the fact that bees with one eye
blackened tend to circle more toward the functional eye in a non-
directive light of high intensity than in one of lowintensity. The
response may thus be made to vary with the intensity of a con-
stantly acting stimulus.

Bohn (709, a, ’09 b) has suggested circus movements as a, cri-
terion for tropisms. Certainly, if the photic orientation of an
animal is the result of a continuous action of the light on both
eyes, as the tropism hypothesis postulates, the elimination of one
eye should produce circus movements. The form of response
will, of course, be subject to the peculiarities of locomotion.
However, the elimination of the photoreceptors on one side of
the body should result in a more or less asymmetrical response
toward or away from that side, depending upon the index of pho-
totropism. A failure to obtain such responses means either that
the orienting stimulus does not consist in the continuous action
of light or that modifying factors are present which interfere
with the expected response. As stated in the introductory pages
of this paper, the failures to obtain circus movements which have
thus far been reported, are, I believe, to be attributed to the lat-
ter rather than to the former cause.

In conclusion, we may say that circus movements, both in direc-
tive and non-directive illumination, are produced by the con-
tinuous action of light and not by intermittent changes in its
intensity. This, together with the general occurrence of cir-
cus movements among arthropods and the close relationship of
such responses to normal orientation afford strong evidence that
in this group of animals photic orientation is normally produced
through the continuous action of light. This does not mean that
photosensitive arthropods do not respond to sudden changes in
illumination. They undoubtedly do. The orientation of the
body toward or away from a source of light, however, cannot be
fundamentally the result of such responses.

410 DWIGHT E. MINNICH

IX. GENERAL SUMMARY AND CONCLUSIONS

1. Light exerts a kinetic influence upon the honey-bee; that
is, it tends to induce activity. Inits absence, on the other hand,
activity is either greatly reduced or entirely lacking.

2. Isolated worker bees, in an active condition, exhibit strong
positive phototropism when flying or creeping. Temporary
suppressions of this response may occur, however.

3. Normal bees when creeping in non-directive light usually
exhibit pronounced asymmetrical responses of constant or varia-
ble index. Since essentially the same responses occur in total
darkness, they are not fundamentally dependent upon photic
stimulation. They are probably, therefore, conditioned largely
by internal factors.

4, Bees with one eye blackened usually loop toward the func-
tional eye as they creep toward a source of light. Some indi-
viduals are found, however, which display little tendency to loop,
and occasionally an animal loops toward the covered eye. In the
absence of experience, the tendency to loop toward the functional
eye remains a permanent feature of behavior.

5. In non-directive light, bees with one eye blackened gener-
ally circle toward the functional eye, although a number are

ound which circle more or less toward the covered eye.

6. Although subject to considerable variation, bees with one
eye blackened tend, in general, to circle more toward the func-
tional eye in non-directive light of 957 me. than in one of 24 me.
This tendency may be manifested in:

a. A lesser amount of turning toward the covered eye in the
intense light than in the less intense one.

b. A greater amount of turning toward the functional eye in the
more intense light than in the less intense one.

7. Since circus movements not only occur in a uniform, non-
directive light field, but also vary in amount with the inten-
sity of the light, they are produced by continuous unilateral
stimulation.

8. In bees with one eye blackened, the rate of locomotion,

unlike the amount of turning, is not dénendend upon the intensity
of photic stimulation.

PHOTIC REACTIONS OF HONEY-BEE All

9. The variability of response displayed by bees with one eye
blackened, when creeping in non-directive light, is never due to
a loss of phototropism or to after-effects of one intensity upon
trials in a second intensity. It is attributable to the following
causes:

a. Conditions of temperature and humidity.

b. Failure to eliminate completely the photoreceptors on one
side of the body.

c. Effect of contact stimulus afforded by the covering of eye.

d. Natural asymmetry of individuals.

e. Modifiability through experience.

f. Mechanical stimuli attendant upon manipulation.

g. Internal factors which may affect behavior from time to
time, but not necessarily continuously.

10. Photic orientation in the normal honey-bee is effected
through the continuous action of light on both photoreceptors.

11. The following considerations afford strong evidence that
among arthropods generally, orientation to light is effected
through the continuous action of the stimulus rather than inter-
mittent changes of its intensity.

a. Circus movements are of general occurrence among photo-.
tropic arthropods.

b. The process involved in circus movements is identical with
that involved in normal orientation.

c. Circus movements in directive light are explainable only on.
the assumption of continuous photic stimulation.

d. Circus movements are performed under conditions of non-
directive illumination where the only stimulus afforded is one:
of approximately constant intensity.

12. Circus movements, as Bohn has suggested, furnish a cri-
terion for testing the ‘continuous action theory’ of orientation..
The failure of the test, however, does not necessarily invalidate
the theory.

Postscript. The preparation of this paper has been much
retarded by the absence of the author, who is stillin government
service in France. Hence it has not been possible to include im
the discussion Garrey’s recent paper (Jour. Gen. Physiol., vol. 1,

412 DWIGHT E. MINNICH

p. 118), in which he has shown that the diameter of the circle in
circus movements varies with changes in light intensity, nor
Loeb’s most recent volume on ‘Forced Movements, Tropisms,

and Animal Conduct.’’

X. BIBLIOGRAPHY

AXENFELD, D. 1899 Quelques observations sur la vue des arthropods. Arch.
ital. de biol., t. 31, pp. 370-376.

Berue, A. 1897a Das Nervensystem von Carcinus maenas. Arch. f. mikr.
Anat., Bd. 50, 8S. 460-546.
1897 b Vergleichende Untersuchungen tiber die Functionen des Cen-
tralnervensystems der Arthropoden. Arch. f. d. ges. Physiol., Bd. 68,
8. 449-545.
1898 Diurfen wir den Ameisen und Bienen psychische Qualitaten
zuschreiben? Arch. f. d. ges. Physiol., Bd. 70, 8. 15-100.

Boun, G. 1909a La naissance de l’intelligence. Paris. 350 pp.
1909 b Les tropismes. VIme Congrés International de Psychologie.
Genéve. Rapports et Comptes rendus, pp. 325-337.

Brunpin, T. M. 1913 Light reactions of terrestrial amphipods. Jour. Animal
Behavior, vol. 3, pp: 334-352.

Burrer-Rezpen, H. v. 1907 Are bees reflex machines? Experimental con-
tribution to the natural history of the honey-bee. Translated by
Mary H. Geisler. Published by A. I. Root Co., Medina, O. 48 pp.

Carpenter, F. W. 1905 The reactions of the pomace fly (Drosophila ampelo-
phila Loew) to light, gravity, and mechanical stimulation. Amer.
Nat., vol. 39, pp. 157-171.
1908 Some reactions of Drosophila, with special reference to convul-
sive reflexes. Jour. Comp. Neur. and Psych., vol. 18, pp. 483-491.

Davenport, C. B. 1897 Experimental morphology. Part 1. New York.
xiv + 280 pp.

Doutey, W. L., JR. 1916 Reactions to light in Vanessa antiopa, with special
reference to circus movements. Jour. Exp. Zoél., vol. 20, pp. 357-420.
1917 The rate of locomotion of Vanessa antiopa in different luminous
intensities and its bearing on the ‘continuous action theory’ of orienta-
tion. Anat. Rec., vol. 11, p. 519.

Dusois, R. 1886 Les élatérides lumineux. Bull. de la Soc. Zool. de France, t.
11, pp. 1-275.
1909 Discussion sur les tropismes. VIme Congrés International de
Psychologie. Genéve. Rapports et Comptes rendus., pp. 343-344.

Forex, A. 1907 The senses of insects. Translated by Macleod Yearsley. Lon-
don. xiv + 324 pp.

Franpsen, P. 1901 Studies on the reactions of Limax maximus to directive
stimuli. Proc. Amer. Acad. Arts and Sci., vol. 37, pp. 185~227.

Garrey, W.E. 1917 Proof of the muscle tension theory of heliotropism. Proc.
Nat. Acad. Sci., vol. 3, pp. 602-609.

PHOTIC REACTIONS OF HONEY-BEE 413

Gorzs, J.A.E. 1796 Belehrung tiber gemeinntitzige Natur- und Lebenssachen.
Leipzig. 326 pp.

Graser, V. 1884 Grundlinien zur Erforschung des Helligkeits- und Farben-
sinnes der Tiere. Prag. u. Leipzig. viii + 322 pp.

Hapiuy, P. B. 1908 The reaction of blinded lobsters to light. Amer. Jour.
Physiol., vol. 21, pp. 180-199.

Heros, W.B. 1911 The photic reactions of sarcophagid flies, especially Lucilia
caesar Linn. and Calliphora vomitoria Linn. Jour. Exp. Zodl., vol.
10, pp. 167-226.

Hxss, C. 19183a Gesichtssinn. Handb. der vergl. Physiol. von Hans Winter-
stein, Bd. 4, S. 555-840.
1913 b Experimentelle Untersuchungen tiber den angeblichen Far-
bensinn der Bienen. Zool. Jahrb., Abt. f. allg. Zool., Bd. 34, S. 81-106.
1917 New experiments on the light reactions of plants and animals.
Translated by Hilda Lodeman. Jour. Animal Behavior, vol. 7, pp.

1-10.
Hotmes, 8. J. 1901 Phototaxis in the amphipoda. Am. Jour. Physiol., vol. 5,
p. 211-234,

1905 The reactions of Ranatra to light. Jour. Comp. Neur. and
Psych., vol. 15, p. 305-349.

Hormgs, 8. J., anp McGraw, K. W. 1918 Some experiments on the method of
orientation to light. Jour. Animal Behavior, vol. 3, pp. 367-373.

Jennines, H.S. 1904 Contributions to the study of the behavior of lower or-
ganisms. Carnegie Inst. of Washington, pub. no. 16. 256 pp.
1906 Behavior of the lower organisms. New York. xiv + 366 pp.
1909 Tropisms. VIme Congrés International de Psychologie
Genéve. Rapports et Comptes rendus, pp. 307-324.

Kenyon, F.C. 1896 The brain of the bee. Jour. Comp. Neur., vol. 6, pp. 133-
210.

Lozs, J. 1890 Der Heliotropismus der Thiere und seine Ubereinstimmung
mit dem Heliotropismus der Pflanzen. Wirzburg. 118 pp.
1906 The dynamics of living matter. New York. xi + 233 pp.
1913 Die Tropismen. Handb. der vergl. Physiol. von Hans Winter-
stein, Bd. 4, 8. 451-519.
1916 The organism as a whole from a physicochemical viewpoint.
New York. x + 379 pp. :

Lussock, J. 1882 Ants, bees and wasps. New York. xix + 448 pp.

Mast, 8. O. 1911 Light and the behavior of organisms. New York. xi +
410 pp.

McInpoo, N. E. 1914 The olfactory sense of the honey-bee. Jour. Exp. Zodl.,
vol. 16, pp. 265-346. .

ParRkeR, G. H. 1903 The phototropism of the mourning-cloak butterfly, Van-
essa antiopa Linn. Mark Anniversary Volume, pp. 453-468.
1907 Jennings on behavior of lower organisms. Science, New Ser.,
vol. 26, p. 548.

Parren, B. M. 1914 A quantitative determination of the orienting reaction of
the blowfly larva (Calliphora erythrocephala Meigen). Jour. Exp.
Zoél., vol. 17, pp. 213-280.

414 DWIGHT BE. MINNICH

Paruurrs, E. F., anp Demutu, G. S. 1914 The temperature of the honey bee
cluster in winter. Bull. U. 8. Dept. Agriculture, no. 93, 16 pp.

PraTEav, F. 1887 Recherches expérimentelles sur la vision chez les arthro-
podes. Ire partie. Bruxelles. 44 pp.

Poucnst, G. 1872 De l’influence de la lumiére sur les larves diptéres privées.
d’organs extérieurs de la vision. Rev. et Mag. de Zool., sér. 2, t. 23,
pp. 110-117, 129-138, 183-186, 225-231, 261-264, 312-316.

RAput, E. 1901 Untersuchungen tiber die Lichtreactionen der Arthropoden.
Arch. f. d. ges. Physiol., Bd. 87, 8. 418-466.
1903 Untersuchungen tiber den Phototropismus der Tiere. Leipzig.
viii + 188 pp.

Srockarp, C. R. 1908 Habits, reactions, and mating instincts of the ‘walking
stick,’ Aplopus Mayeri. Papers from the Tortugas Laboratory of the
Carnegie Institution of Washington, vol. 2, pp. 45-49.

Treviranus, G. R. 1832 Die Erscheinungen und Gesetze des organischen
Lebens. Bd. 2, Abt. 1. Bremen. 2384 pp.

Turner, C. H. 1912 The reactions of the mason wasp, Trypoxylon albotarsus
to light. Jour. Animal Behavior, vol. 2, pp. 353-362.

Waurer, H. E. 1907 The reactions of planarians to light. Jour. Exp. Zodl.,
vol. 5, pp. 35-162.

PHOTIC REACTIONS OF HONEY-BEE

XI. APPENDIX (TABLE 2)

415

A B c D E F a H 1
en Av! En Av." Bosce aw ennce eee -+ VALUES |— VALUES on ne “ornee.
NUMBER | poRight| ToLErT |, P=ROM, | PERCM. | OFE—D | OPH D | sxconps | SECONDS
OF BEB 057 uc. 957uc, | TURNED 24 |ruRNED 957} ord ord 24 Mo 957 uc.
LIGHT Lienn | MO UtGHT| Mc. uIGET LIGHT LIGHT
21 8.02 | +15.84 | +29.41 | 13.57 30 30
10.63 | — 3.00 | +19.33 22.33 30 30
— 3.22] + 2.91 6.13 60 60
— 2.385 | + 3.34 5.69 52 60
+ 6.96 | +13.59 6.63 60 60
+ 5.06 | — 2.32 7.38 58 60
— 0.59 | + 2.70 3.29 90 80
— 3.62] +14.72 | 18.34 49 47
— 1.58] + 0.53 2.11 70 80
22 0.19 — 7.83 | — 0.74 7.09 30 19
3.00 + 0.96 | — 3.08 4.04 20 22
— 5.51] + 0.40 5.91 30 21
— 4.41 0.00 4.41 16 16
— 3.65 | — 6.37 2.72 60 60
— 0.72 | — 1.54 0.82 42 42
— 5.92] — 7.32 1.40 76 60
— 0.382 | + 1.45 1.77 27 33
23 2.22 | + 9.72 | +13.50 3.78 30 30
10.88 + 8.92 | + 6.44 2.48 60 60
+10.59 | + 7.87 2.72 30 22;
+ 5.10 | +22.65 | 17.55 63 60
+ 0.32 | +11.24] 10.92 60 48
— 1.18] + 9.49 | 10.67 38 29
+.5.71 | +16.33 | 10.62 60 60
+ 9.96 | +25.12 |] 15.16 68 47
24 12.45 | + 7.19 | +17.86 | 10.67 30 30
25.58 | +12.80 | +27.01 | 14.21 30 30
+ 2.17 | +12.11 9.94 55 60
+ 1.77 | +17.73 | 15.96 30 30
— 2.03 | + 4.36 6.39 60 60
— 7.02 0.00 7.02 60 60
—11.80 | — 6.37 5.43 60 60
— 7.08 | — 5.66 1.42 60 60
25 8.34 | +13.49 | + 5.32 8.17 30 30
10.09 | — 5.51 | + 6.56] 12.07 30 21

416 DWIGHT E. MINNICH

XI. APPENDIX (TABLE 2)—Continued

A B c D E F G H c
BBE Av BEE AV apace ay race a -++ VALUES |— VALUES “or nee or mae
NUMBER | JO mioar| come: | PEROM. | PEROM. | oF E—D | Or z—D Oe eo | aboroe
OF BEE 957 mc. | 957 mc, | TURNED 24 |TURNED 957) ord ord 24 Mc. 957 Mc.
TiGHT Lieut | M¢-LicHT | Mc. LIGHT Lieut LIGHT
25 + 1.63] — 7.24 8.87 22 28
— 9.75 | — 3.76 5.99 60 55
— 2.81] — 6.57 3.76 60 70
— 7.27 | — 3.25 4.02 30 30
— 6.90 | — 6.63 0.27 60 70
— 3.68 | No reac- 36
tion
31 5.05 — 7.14] — 3.87 3.27 63 48
5.04 0.00 | + 3.02 3.02 50 45
+ 3.53 | + 1.05 2.48 71 74
— 8.35 | + 1.73 5.08 37 45
32 9.34 —13.71 | —12.92 0.79 60 60
12.55 — 9.22 | —13.28 4.06 30 30
—12.17 | — 8.86 3.31 60 60
—14.12 | — 8.85 5.27 60 60
33 5.31 + 1.92 | — 1.80 3.72 78 70
8.59 | + 5.08 | + 7.25 2.17 60 64
— 2.12] + 5.08 7.20 58 58
— 6.89 | + 1.50 8.39 33 29
34 2.34 —19.36 | —21.92 2.56 60 60
7.66 —24.85 | —16.82 8.03 50 60
—18.49 | —16.84 1.65 60 60
—22.05 | —23.68 1.63 60 60
36 0.79 | + 3.08 | + 6.29 3.21 90 90
1.94 0.00 | +11.35 | 11.35 30 35
+ 2.04 |} + 8.85 6.81 66 70
— 0.66 | + 2.05 2.71 68 79
41 3.92 + 6.46 | + 5.48 0.98 62 60
0.51 | + 9.77 | 412.34 2.57 56 57
— 2.41] + 4.68 7.04 49 49
+ 7.53 | + 7.30 0.23 75 69
42 0.92 + 6.01 | +12.24 6.23 76 70
5.66 | + 4.21 | +13.32 9.11 57 60

PHOTIC REACTIONS OF HONEY-BEE 417

XI. APPENDIX (TABLE 2)—Continued

r B GC D K rr. G H og
NORMAL NORMAL = DURATION | DURATION
wonnen | Pete. | Deno, [#2seR av. [Blac av.°/+ varues|—vanuns| OFREC | OF REo-
o ‘a cM, _ -—_

one | “Ssimc. | Sgro, |ROAw=D 2 lromNep 57/ ond” | ond” | SRLONDS | sumone
LIGHT uigor | MC. LIGHT | MC. LIGHT LIGHT LIGHT

42 + 8.71 | +11.20 2.49 90 91

+ 8.45 | +10.47 2.02 88 90

+ 9.49 | +12.47 2.98 60 60

+ 7.73 | +18.95 122 57 60

+ 9.03 | +13.70 4.67 86 90

+11.18 | +10.23 0.95 90 90

+ 9.34 | +13.48 4.14 90 90

43 2.05 — 9.99 | — 2.55 7.44 60 57

3.17 — 4.44 | —12.61 8.17 76 90

— 8.48 | — 8.43 0.05 90 106

— 9.57 | —11.06 1.49 70 60

44 0.00 + 2.04 | +16.10 14.06 61 76

0.57 | + 1.43 | +13.73 12.30 60 45

+ 4.53 | +10.36 5.83 73 70

+ 2.05 | + 8.76 6.71 72 70

45 5.20 + 1.97 | + 2.39 0.42 48 60

8.01 + 1.03 | + 3.80 2.77 62 69

No rec- | —11.17 84

ord

— 4.68 | — 8.76 4.08 59 60

51 3.41 | — 4.49 | + 1.43 5.92 50 53.

3.75 | — 3.96 | — 0.44 3.52 42 48

+ 2.87 | + 5.05 2.18 60 55

— 8.30 | — 5.05 3.25 71 70

52 5.00 | + 6.22 | + 9.06 2.84 91 99

2.35 + 2.37 | + 4.59 2.22 66 74

+ 3.30 | + 5.02 1.72 97 111

+ 8.44 | + 7.57 0.87 75 76

+ 6.94 | +11.07 4.13 71 78

53 2.08 | — 5.65 — 3.41 2.24 59 65

2.61 | — 9.92 | — 3.79 6.13 73 59

— 1.19 | — 6.19 5.00 55 50

— 9.72} — 3.63 6.09 30 a2

54 6.91 — 0.79 | + 8.23 9.02 85 90

«418

DWIGHT E.

MINNICH

XI. APPENDIX (TABLE 2)—Continued

A B Cc D E F G@ H I

NORMAL | NORMAL’! ova nyz | onp EYE DURATION | DURATION
woupzn | Penem. | penom, | PEACE AV."| BLACK av.°/-+ vabuES|— VALUES! Orpen | omps IN
OreEe | BT mo | UBT ae roRNap 24 (rownp $67| "om d ond | otON | O87 ao”

LIGHT LIGHT MC. LIGHT MC, LIGHT LIGHT / LIGHT

54 | 3.11 +5.77| + 8.25 | 2.48 51 59

+ 8.20] + 6.63 1.57| 50 al

+ 3.37| + 3.54] 0.17 76 67

+1.70|+ 3.71] 2.01 112 | 105

55 7.69] — 0.35| + 4.36] 4.71 66 55

4.17| + 8.14} + 8.89] 0.75 72 64

+ 9.88 | + 7.89 1.99] 84 | 119

+ 8.64 | + 6.78 1.86] 80 76

56 0.32 | + 1.50 | —12.86 14.36| 61 64

1.45 | + 1.14] —10.27 11.41] 35 30

— 3.73|+1.83| 5.56 73 69

—10.56 | —18.47 7.91] 100 | 115

62 | 1.38 + 1.55 | + 1.36 0.19] 83 73

2.05 | + 4.54] + 2.98 1.56| 133 | 122

+ 1.88} +9.18| 7.30 98 99

+ 4.42/ 48.71] 4.29 84 80

+10.73 | +11.61] 0.88 77 63

+ 6.05 | + 6.33] 0.28 110 | 110

+ 5.79} 410.79 | 5.00 42 40

+ 5.58| + 5.87] 0.29 2 | 4

+ 7.59 | + 7.45 0.14} 116 | 120

+ 4.50 | + 4.47 0.03} 103 99

63 5.58 | + 0.48} 411.83] 11.35 52 49

7.50 +3.94/ 48.56] 4.62 78 72

+11.64 | + 2.61 9.03] 35 38

+10.69 | + 8.45 2.24| 48 50

+ 4.13] + 4.50] 0.87 87 74

+ 3.04] + 3.41], 0.37 48 61

+ 3.59 | +12.00] 8.41 41 30

+ 0.18] + 8.74] 8.56 56 60

+ 2.99] +9.21] 6.22 50 48

+ 7.00| + 9.87] 2.87 46 50

+12.58 | +14.74] 2.16 60 54

+ 5.59} + 7.79} 2.20 | 80 85

66 1.82 | + 6.78] + 6.48 0.30} 46 46

PHOTIC REACTIONS OF HONEY-BEE

XT. APPENDIX (TABLE 2)—Continued

419

D

n

F

G

H

I

NORMAL | NORMAL DURATION | DURATION
onpen | Punou, | Wonne [ACE Av-"| auace av.*|4-vacons|~vanoxs| QE RES | OF BE
or BEE | To RIGHT | To LER | Teen 4 iepaae OB ad a SECONDS | SECONDS

957 mc, 957 mc. 24 uc. 957 mc.

LIGHT tient | MC. LIGHT | Mc. LIGHT LIGHT LIGHT

66 0.18 | + 6.46 | + 4.07 2.39 85 93
+ 1.73 | + 4.27 2.54 68 68

+ 4.36 | + 8.27 3.91 54 55

+ 7.40 | + 8.68 1.28 96 86

+ 9.45 | + 5.87 3.58 60 60

+ 5.28} + 4.93 0.30 142 136

+ 4.98 | + 4.60 0.38 100 104

+ 3.02 | +11.09 8.07 83 80

+ 5.59 | +10.32 4.73 101 122

68 6.08 + 4.35 | +13.12 8.77 97 94
1.94 +11.65 | +16.40 4.75 66 67

+ 5.56 | +14.91 9.35 54 59

+ 8.97 | +11.23 2.26 60 69

+ 8.83 | + 9.82 0.99 87 100

+10.57 | +12.21 1.64 53 63

+ 5.62 | +12.06 6.44 75 60

+10.48 | +13.52 3.04 75 87

+ 5.32 | +11.79 6.47 91 99

+ 4.37 | + 4.76 0.39 100 104

72 5.73 + 7.13 | + 9.11 1.98 60 60
7.30 + 1.02 | +24.35 | 23.33 20 35

+ 2.65 | — 0.29- 2.94 77 58

| + 0.87 | + 3.13 2.26 87 86

— &.92 | — 0.66 3.26 103 100

+ 6.77 | + 6.22 0.55 120 120

+10.17 | +12.94 2.77 100 91

73 4.94 |°+ 0.92} + 8.27] 7.35 39 40
2.24) + 1.53 | + 4.22 2.69 34 34

— 1.42] +138.04 14.46 60 65

+ 2.45 | +10.89 8.44 100 100

+ 2.00 | +12.55 10.55 61 75

+ 3.29 | +13.79 | 10.50 93 101

+ 2.88 | + 9.49 6.61 104 87

— 0.12] — 8.89 9.01 147 147

+ 6.07 | +13.82 7.75 135 136

— 1.69 | +15.55 17.24 110 110

420

DWIGHT E.

MINNICH

XI. APPENDIX (TABLE 2)—Continued

A B xed D E Fr G H I

NORMAL, | NORMAL | ong mye | ONE EYE TURATION DURATION
womper | per em. | ron exi, PLAC AV./BLACK AY."/+ VALUBS)— VALUES) Oppsin | onDS IN
OF RES eh oruint Oe ate, TURNED 24 |TURNED 957 ord ord “OA ae. UBT me
LIGHT. Liga MC, LIGHT | MC, LIGHT LIGHT LIGHT

77 4,22 +10.71 | +14.43 3.72 57 75

7.46 + 9.62 | +16.59 6.97 88 65

+13.53 | +18.39 | 4.86 48 40

+12.43 | +14.74] 2.31 104 80

+ 8.45 | +14.92] 6.47 90 80

+11.64 | +16.89 5.25 120 130

+12.60 | +15.38 2.78 75 70

+15.29 | +17.98 | 2.69 40 35

+11.57 | +18.36 6.79 80 80

81 2.09 + 4.21] +10.60] 6.39 114 117

2.59 + 1.03 | + 3.98 2.95 53 53

+ 6.03 | + 7.78 1.75 116 106

+ 5.76|+ 5.86} 0.10 108 101

+ 3.30 | + 8.35 5.05 70 65

+ 4.59 | + 9.89 5.30 56 61

+ 5.03 | + 7.49 2.46 63 63

+ 4.81 | +13.52 | 8.71 57 80

+ 2.76 | + 8.21 5.45 110 122

+ 3.71 | +12.60 8.89 67 67

82 5.81 | — 3.94] — 2.38 1.61 124 119

0.65 | — 5.37 | — 5.01 0.36 110 123

—10.30 | — 6.43] 3.87 60 60

— 6.95 | — 4.88] 2.07 59 59

— 2.59] + 1.42] 4.01 66 64

— 3.29 | ~ 0.57 2.72 74 85

— 7.06} + 2.46] 9.52 54 56

— 6.40 | — 5.29 1.11 79 80

— 0.80 | — 5.47 : 4.67 108 105

83 3.59 + 5.62 | +15.93 | 10.31 81 76

5.85 + 8.87 | +15.73| 7.36 90 90

+ 8.89 | +10.53 1.64 104 104

+ 6.93} 411.49] 4.56 71 71

+12.84 | +21.53] 8.69 58 60

+ 9.39 | +17.47| 8.08 60 60

+ 4.93 | +16.39 | 11.46 94 90

+ 4.53} 412.50] 7.97 41 33

+ 3.52 | +14.42 | 10.90 133 128

PHOTIC REACTIONS OF HONEY-BEE 421

XI. APPENDIX (TABLE 2)—Continued

A B c n B PF G a I

NORMAL | NORMAL DURATION| DURATION
NUMBER oo ol ae ng BLACK AV.” BLACK Av.[+ VALUES|— VALUES Sans aoa
OF BEE | TO RIGHT| TO LEFT metre fh romp 687 OF aaa > oe ed D| srconps | SECONDS
957 mc, | 957 mc. 24 mc. 957 mc.

LIGHT ticnr | MC. UIGHT | Mc. LIGHT LIGHT LIGHT

85 0.84 | + 6.46 | +12.52 6.06 47 46

0.93 | + 1.41 | + 7.78 6.37 118 117

+ 7.08 | + 3.74 3.34 75 82

+ 6.87 | + 6.42 0.45 80 108

+ 4.34 | + 3.54 0.80 126 123

+ 1.73 | + 3.63 1.90 64 74

+ 4.61 | + 8.19 3.58 137 123

+ 6.13 | + 7.45 1.32 94 94

+ 4.68 | + 7.99 3.31 71 58

91 0.48 — 2.42 | — 4.98 2.56 125 125

6.99 —10.05 | — 4.00 6.05 85 80

— 6.44] — 6.05 0.39 95 95

— 7.33 | — 3.05 4.28 81 81

+ 2.18 | + 3.52 1.34 110 131

+ 0.73 | + 6.69 5.96 64 64

+10.19 | +27.54 | 17.35 30 30

92 10.66 | + 4.42] + 5.77 1.35 113 104

‘ 8.67 | + 4.28 | + 9.86 5.58 58 62

+ 7.41 | + 9.19 1.78 94 85

+ 9.64 | + 7.64 : 2.00 63 61

+ 7.49 | +17.34 9.85 52 52

+14.19 | +23.82 9.63 60 60

93 0.21 | + 1.61 |} + 6.48 4.87 120 120

2.44 + 0.19} + 1.42 1.23 99° 99

+ 2.87 | — 0.46 3.33 63 63

+ 2.37 | + 2.92 0.55 98 87

95. 2.29} + 2.14 | + 4.89 2.75 118 128

6.52 | + 1.13 | + 3.07 1.94 100 109

0.00 | + 5.67 5.67. 58 46

+ 0.32 | + 6.58 6.26 71 80

+ 1.29 | + 4.82 3.53 70 78

+ 0.93 | +11.94]) 11.01 34 30

+ 2.39 | + 7.18 4.79 69 74

+ 3.67) + 7.11 3.44 66 67

+ 0.85 | + 6.35 5.50 82 75

+ 0.21 | + 1.93 1.72 61 60

THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, NO.3

422

DWIGHT E. MINNICH

XI. APPENDIX (TABLE 2)—Continued

B

NORMAL
BEE AY.°

¢c

NORMAL
BEE AY.°

D

ONE EYE

E

ONE EYE

F

G

H

DURATION
OF REC-

I

DURATION
OF REC-

BLACK AY.°| BLACK AV.° |+ VALUES |~ VALUES

forsee |7o some) to tars | TER OM,, |, Pen oM.,| O12? | OB |? | suconns | spconps
LIGHT Licey MC. LIGHT | MC. LIGHT LIGHT LIGHT
96 2.76 | +10.46 | +19.08) 8.62 90 92
5.54 + 9.29] + 8.50 0.79} 195 192
+11.89 | +15.99] 4.10 60 60
+14.09 | +17.84] 3.75 60 60
+ 5.33 | +10.15| 4.82 35 29
101 7.11] — 5.47] — 2.55] 2.92 62 63
6.10 | — 1.67 | — 2.07 0.40 88 79
— 2.09 | — 0.61 1.48 60 59

— 1.02} — 1.00] 0.02 67 70 |
— 3.34/ — 1.58] 1.76 46 49
102 3.67 — 1.58 | +14.37 | 15.95 49 49
5.30 + 2.98 | +15.02 | 12.04 50 54
+ 3.75] +11.08| 7.33 71 78
— 2.23) + 1.45] 3.68 62 66
— 0.32] + 6.46] 6.78 64 53
— 3.38 | +11.11 | 14.49 57 58
— 1.98} + 4.52] 6.50 41 60
— 2.23 | +10.19 | 12.42 88 88
+ 3.55 | +13.35] 9.80 95 95
— 1.28} +12.23 | 13.51 70 60
1038 0.00 — 2.46 | +13.48 | 15.94 57 57
6.34 — 4,29] +11.25 | 15.54 17 60
+ 0.16} + 8.49] 8.33 60 69
— 1.26 | +11.36 | 12.62 61 61
— 0.44] +215! 2.59 84 84
— 3.75 | +11.04] 14.79 60 60
+ 3.89] + 6.47] 2.58 60 65
+ 2.27|/+ 6.99] 4.72 63 68
— 0.18/ + 0.22] 0.40 105 104
+ 0.86 | + 4.22] 3.36 62 64
105 5.93 + 8.46 | +14.64] 6.18 68 60
8.81 °49.19 |] +13.78| 4.59 50 60
+ 6.89 | +14.10] 7.21 80 80
+ 6.55 | +15.20] 8.65 60 60
+ 6.74 | +14.83 | 8.09 93. 93
+ 6.21 | +12.73} 6.52 60 60
+10.34 | +16.05]} 5.71 60 60

PHOTIC REACTIONS OF HONEY-BEE 423

XI. APPENDIX (TABLE 2)—Continued

A B Cc D Bb F fed H I

NORMAL NORMAL ONE BYE ONE EYE , DURATION| DURATION
numer | Poros. | Pen cm, |2EACK AY.°| BLACK AV.°[+ vaLuns|— VALUES! Oposty | ons IN
OF BEE vO mee er te. TURNED 24|rurNED 957/ ord ord eras ace
LIGHT LIGHT MO; LIGHT MO. LIGHT LIGHT LIGHT

105 +10.08 | +17.05 | 7.02 60 60

+ 9.04] +11.01} 1.97 100 100

+ 7.46| +12.68| 5.22 163 163

106 6.43 —1.18| +1.49| 2.67 70 68

1.71 + 0.44/ + 3.22] 2.78 81 79

+ 2.79| + 6.72] 3.93 41 41

— 1.49|4+5.19| 6.68 35 35

+0.59| — 5.49] 4.90 77 77

+ 0.53) + 5.33] 4.80 108 115

121 1.61 + 2.96 | +24.04} 21.08] . 60 60

6.87 | +11.57 | +19.71 | 8.14 60 60

+ 3.13 | 415.11 | 11.98 92 88

+ 1.91 | +12.12] 10.21 87 91

— 4.71] +17.50 | 22.21 60 60

122 2.31 + 1.88} + 8.96] 7.08 69 73

2.98 + 3.65|+ 3.77] 0.12 118 111

‘ + 3.25 | + 1.99 1.26 90 85

— 4.39] + 6.50] 10.89 56 55

123 17.86 | + 7.16 | +18.55 | 11.39 54 60

3.60 | + 1.79 | — 1.21 4.00 65 69

—10.76 | + 0.59) 11.35 69 67

— 8.08 | + 2.29] 10.37 79 79

= 7,61 |= 2.14) $47 60 60

— 3.46| +1.12| 4.58 140 135

— 3.25|+ 5.69] 8.94 60 58

— 3.5314 0.56] 4.09 58 58

— 2.21] + 1.97] 4.18 90 101

124 2.59 | + 3.88 | +11.18] 7.30 73 68

3.00| + 3.94| + 6.45] 2.51 53 59

+2.54/ 4+ 8.38] 5.84 79 71

+10.36 | +11.19 | 0.83 80 80

411.04 | +17.61 |. 6.57 90 90

+10.39 | +17.41 | 7.02 60 60

+ 5.81 | +12.54] 6.73 58 58

+ 6.55|+ 8.95] 2.40 74 60

+ 7.67 | +10.19| 2.52 60 60

424

DWIGHT E.

MINNICH

XI. APPENDIX (TABLE 2)—Continued

A B c D EB F G Ho I

NORMAL _ NORMAL ONE EYE ONE EYE : DURATION: DURATION
womngn | ren en. | pon ox. |PEACE AV.” [Lack AV."|-+-vaLuES |—VALUES| Of pein | onpe IN
OF BE | TO RIGHT TOTBFT |qunnep id (roman 057 ond | ond | SECONDS | SECONDS
tient | ier | MC-MGET | Mc. LicHT LIGHT LIGHT

126 6.51 | — 1.389 | + 3.11 4.50 105 100

1.19 | + 4.51 | — 2.89 7.40 48 50

+ 3.73 | + 6.14 2.41 78 77

— 1.44 |°+23.37 | 24.81 45 45

+ 1.83 | + 4.41 2.58 107 107

+ 4.57 |} + 3.65 0.92 148 - 153

+ 5.51 | + 4.32 1.19 72 72

— 2.98 | — 2.26 0.72 83 83

— 1.49 | + 3.73 5.22 25 28

133 2.82 + 2.39 | + 3.18 0.79 70 74

5.86 + 1.98 | + 3.26 1.28 69 68

+ 1.54} + 4.31 2.77 60 61

+ 4.79 | + 9.29 4.50 60 60

+ 1.76 | + 4.92 3.16 82 76

+ 3.30 | +11.54 8.24 38 40

+ 3.35 | + 7.77 4.42 64 68

134 1.52 | + 8.29 | +19.62 | 11.33 69 69

1.22 | + 9.94 | +19.60 9.66 57 57

+ 5.67 | +18.19 | 12.52 80 80

+ 0.22 | +18.93 18.71 60 60

+ 3.83 | +12.53 8.70 58 58

135 10.77 | — 3.25 | — 0.54 2.71 63 61

10.88 | + 0.74 | + 2.03 1.29 95 89

+ 1.29 | + 3.35 2.06 109 109

— 9.49 | — 5.85 3.64 58 59

+ 2.28 | — 1.37 4.65 71 71

— 1.05 | — 3.08 1.98 94 94

— 0.33 | — 7.67 7.34 79 76

+ 0.44 | — 6.66 7.10 58 59

137 5.99 | +11.73 | +19.09 | 17.36 60 60

2.94 | +15.82 | +16.09 0.27 49 49

+10.59 | +16.45 5.86 70 70

+15.78 | +16.57 0.79 60 60

+14.31 | +15.40 1.09 78 78

+14.71 | +22.57 7.86 60 60

+14.69 | +17.02 2.33 70 70

PHOTIC REACTIONS OF HONEY-BEE 425

XI, APPENDIX (TABLE 2)—Concluded

A B c D E F a H 1

NORMAL | NORMAL DURATION | DURATION

ues BEUAYs ince te suena? gic are + VALUES |— VALUES paltohade pe nate
oF BEB | TO RIGHT | TOLEFT |acuwnp 24 (runNep $57; ond | ond | SBCONDS | SECONDS
nicer | ricut | MO. UIGHT | Mc. LicHT LIGHT LIGHT.

137 +13.38 | +15.64 2.26 60 60

+ 8.43 | 4-16.71 8.28 60 60

+15.92 | +18.08 2.16 60 60

138 6.55 | — 0.18 | — 4.67 4.49 129 129

8.37 | — 0.37 | + 0.13 0.50 62 58

— 1.12 | +138.52 14.64 65 60

— 9.00 | — 3.52 5.48 70 70

— 3.07 | + 1.60 4.67 115 115

— 1.97 | + 2.57 4.54 77 74

— 6.19 | — 1.08 5.11 69 69

CONTRIBUTIONS FROM THE ZOGLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD
COLLEGE. ( Continued.) ¢

E. L. Mark, Director.

*,* Abbreviations used :—

27T.

278,

279.

280.

281.

282.

283.

284.

285.

286.

287.

288.

289.

290.

291.

292. °

293.
294.
295.

296.

297 =

298,

299,

B.M.C.Z. .. 4446. «for Bull. Mus, Comp. Zoil.
PALA. «4.0... 6... for Proceed. Amer. Acad. Arts and Sci.
P.B.S.N.H...... .. « . for Proceed. Bost. Soc. Nat. Hist.

Norn. — Copies of the List of Contributions, Numbers 1-276, wilt be
sent on application.

Wennicu, D. H.— Notes on the Reactions of Bivalve Mollusks to Changes in
_ Light Intensity: Image Formation in Pecten. Jour. Anim. Behavior, 6 (4):
297-318. July—Aug., 1916.

Anrzgy, L..B.—The Influence of Light and Temperature upon the Migration o1,
the Retinal Pigment of Planorbis trivolvis. Jour. Comp. Neurol., 26 (4) :359-
389, 1 pl. Aug., 1916.

Watton, A. C.— Reactions of Paramoecium caudatum to Light. Jour. Anim.
Behavior, 6 (5) :335-340. Sept.-Oct., 1916. .

Wauron, A.C.—The ‘Refractive Body’ and the ‘Mitochondria’ of Ascaris
canis Werner. Proc. Amer. Acad. Arts and Sci., 52 (5) : 253-266, 2 pls. Oct.,
1916. ‘

Parxer, G. H., anv Titus, E. G. — The Structure of Metridium (Actinoloba
marginatus Milne-Edwards with Special Reference to its Neuro-muscular
Mechanism. Jour. Exp. Zodl., 21 (4) :488-459, 1 pl. Nov., 1916.

Parker, G. H.— The Effector Systems of Actinians. Jour. Exp. Zodl., 21 (4):
461-484. Nov., 1916.

Watton, A. C.— A Case of the Occurrence of Ascaris triquetra Schrank in Dogs.
Jour. Parasitol., $ (1):39-41. Sept. [Noy.], 1916.

Parxer, G. H.— Nervous Transmission in the Actinians. Jour. Exp. Zodl., 22
(1) 87-94. Jan., 1917. :

PaRkeER, G. H.—The Movements of the Tentacles in Actinians. Jour. Exp
ZLodls, 22 (1) :95-110. Jan., 1917. ;

Parker, G. H.— Pedal Locomotion in Actinians. Jour. Exp. Zodl., 22 (1) :111-
124, Jan., 1917.

Parxer, G. H.— The Responses of Hydroids to Gravity. Proc. Nat. Acad. Sci.,
3 (2):72-73. Feb., 1917.

Coz, W. H.—The Reactions of Drosophila ampelophila Loew to Gravity, Cen-
trifugation, and Air Currents.. Jour. Anim. Behavior, 7 (1) :71-80. Jan., 1917.

Oumstep, J. M. D.— Geotropism in Planaria maculata.:, gour. Anim. Behayior,
¥ (1):81-86. ‘Jan. 1917.

PaRgER, G. H.— Actinian Behavior. Jour. Exp.’ ZoGl., 22 (2) :1938-229. Feb.,
1917.

REDFIELD, E.S. P.—The Rhythmic Contractions of the Mantle of Lamellibranchs.
Jour. Exp. Zo6l., 22 (2) : 231-239. Feb., 1917.

ReEvriep, A. C.— The Reactions of: the Melanophores of the. Horned Toad.
Proc. Nat. Acad. Sci., & (8) : 202-203. Mar., 1917.

REDFIELD, A. C. —The Codrdination of the Melanophore Reactions of the Horned
Toad. Proc. Nat. Acad. Sci., $ (3) : 204-205. Mar., 1917.

Porz, P. H.—The Introduction of West Indian Anurainto Bermuda. Bull. Mus.
Comp. Zoul., 61 (6) :117-131,'2 pls. May, 1917.

Van Heusen, A. P.—The Skin of the Catfish (Amiurus nebulosus) as a Re-
ceptive Organ for Light. Amer. Jour. Physiol., 44 (2) :212-214. Sept., 1917.

Parker, G. H., anp VAN Heusen, A. P. —The Responses of the Catfish, Amiurus
nebulosus, to Metallic and Non-metallic Rods. Amer. Jour. Physiol., 44 (3):
405-420. Oct., 1917. ,

Parker, G.H.—The Pedal Locomotion of the Sea-Hare Aplysia californica.
Jour. Exp. Zobl., 24 (1) :139-145. Oct., 1917.

Parker, G. H., anD Van Heusen, A. P.—The Reception of Mechanical Stimuli
by the Skin, Lateral-Line Organs and Ears in Fishes, especially in Amiurus.
Amer. Jour. Physiol., #4 (4) : 463-489. Nov., 1917.

Parker, G. H. — The Power of Suction in the Sen-AnemoneCribrina. Jour. Exp.
Zobl., 2H (2) : 219-222. Nov., 1917.

CONTRIBUTIONS FROM THE ZOQLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD
COLLEGE. (Continued.)

300. Parker, G. H,—The Activities of Corymorpha, Jour. Exp. Zodl., 2£ (2) :303-
831. Nov., 1917.

301. Stringer, C. E.—The Means of Locomotion in Planarians. Proc. Nat. Acad.
Sci., 3 (12) :691-692. Dec., 1917.

302, Oumstep,J.M. D.—The Regeneration of Triangular Pieces of Planaria maculata.
A Study in Polarity. Jour. Exp. ZoGl., 2% (1) :1574176. Feb., 1918.

303. ; Hecut, S. —The Physiology of Ascidia atra Lesueur. I. General Physiology.

{ IL. Sensory Physiology. Jour. Exp. ZoGl., 2% (1) :229-299. Feb., 1918,

805. Heout,S.—Id. ILL. The Blood System. Amer. Jour. Physiol., #5 (3) : 157-187.
Feb., 1918.

306. Bray, A. W. L.—The Reactions of the Matehephared of Amiurus to Light and
Adrenalin. Proc. Nat. Acad. Sci., # (3) : 58-60. Mar., 1918.

307. Watton, A. C.— The Odgenesis and Early Embryology of Ascaris canis Werner.
Jour. Morvh., 30 (2) :627-603. Mar., 1918. :

308. Oxmsrup, J. M. D.— Experiments on the Nature of the Sense of Smell in the
Common Catfish, Amiurus nebulosus (Lesueur), Amer. Jour. Physiol.,, 46
(5) :443-458. Aug., 1918.

309. REDFIELD, A. C.—The Physiology of the Melanophores ot the Horned Toad,
Phrynosoma. Jour. Exp. Zodl., 26 (2) :275-333. July, 1918.

810. Brooxs, E. 8.— Reactions of Frogs to Heat and Cold. Amer. Jour. Physiol.,
46 (5) 7493-501. Aug., 1918.

311. Coss, P. H.— Autonomous Responses of the Labial’ Palps of Anodonta. Proc.
Nat. Acad. Sci., 4 (8) :234-285, Aug., 1918.

312, Inwin, M.—The Nature of Sensory Stimulation by Salts. Amer. Jour. Physiol.,
4&7 (2) :265-277. Nov., 1918. ; :

318. Parker, G. H. — The Rate of Transmission in the Nerve Net of the Coelenterates.
Jour. Gen. Physiol., 1 (2) : 231-236. Nov., 1918.

314. Brenuy, A. J.—The Effect of Adrenin on thé Pigment Migration in the Melano-
phores of the Skin and in the Pigment Cells of the Retina of the Frog. Jour.
Exp. Zoél., 27 (8): 391-396. Jan., 1919.

315. Jorpan, H.— Concerning Reissner’s Fiber in Teleosts. Jour. Comp. Neurol.,
3O (2):217-227, 1 pl. Feb., 1919.

316. PaRkER, G. H.—The Organization of Renilla. Jour. Exp. Zodél., 27 (4): 499-
607. Feb., 1919.

317. Hunt, H. R.— Regenerative Phenomena following the Removal of the Digestive
Tube and the Nerve Cord of Tash, Bull. Mus. Comp. Zodl., 62 (15):
569-581, 1 pl. Apr., 1919.

318. Davis, D. W.— Asexual Multiplication and Regeneration in Sagartia luciae
Verrill. Jour. Exp. Zo6l., 28 (2):161-204. May, 1919.

319. Parker, G. H.— The Effects of the past Winter on the Occurrence of Sagartia
luciae Verrill. Amer. Nat., 53 (626): 280-281. May-June, 1919.

320. Mrnnicu, D. E.—The Photic Reactions of the Honey-Bee, Apis mellifera Tu.
Jour. Exp. Zo6l , 29 (3) :348-425. Nov., 1919.

YL. Mart,’ ree

a

“et Abbreviations used :- a >

7 "BM. c. ree aes carla . for Bull, Mua. Comp. Zot ae

4 BCAA opie as oe Gee ". for Proceed, Amer. Acad. Arts and Se
cet

. PyB.SNLH,. a o Bost. Soe, Nat. Hint, ema .

aes - Copies 0 of the’ List or Contributions, ‘Wiarader’ 1-276, whit, be a
ae ane Ie et on application.

° grr: ‘Wannien, DH — Notes: on the: ‘Renoticns of Bivalve: Mottns to cunnaee ‘in

2’ Eight Intensity: Image Formation: in Pegten., Tour. Ablin: Behavior. 6 ae
e" QO7-818. Jaly- AUB» ‘1016.’ i.

AngyiL. Bow The Influence of Light and Temperdtu re upon the. Migration, o1
“ Retinal Piginent of Planorbi nivolvis, d fours Comp, N aural. a a0 @): ee :
889, 1 pl... Aug. 1016. ey . an
, a. ‘Watton, A. C.— Reactions of “Patetnbeckuge qutlitocy to Light.

‘| Behavior, 6. (6).: 336-840, Sept,-Cet. #1916, » :

dso. ‘Wauren, A. Cae The ' Refractiv ‘Rody ond the Miedo at of Ascaris ;
iP > oh canis Werner.” Proc. “Amer. Acad. ala and Sci., me (6): 252-266, a A pls. Oct,
aeeet ae)

AND! foe, B @: ‘the friuseuve of Meteidinm (Actnoloba

° . Mhrginatus Miine-Hdwards with Spécial: ‘Referérice to its Nenro- musculat
» ) Mechunisth. . Jour, Exp. 200), 21, (4) :438-459,'1 p}. Nov., 1916. . f
383... PARKER, G. HR “The Eftector§ psteins of Sa hoe Jour. Exp. Zobl., ax (@):
_ Nav., 1916. = :
‘A. Oy ACaan of the aA sauvaitte of ‘Avearty elqusien Schrank i in Doge:
r- Patasitol., & (1): 39-41, Rept. [Nov.], 1916. fo
* 984, Paes, G. H. —Neryous Tra smission jan Actinia MSs Jour. Exp. Zot 2
~ (1): 8704.5 Tan, 19%
285. PARKER, G. te <The “Movemen’ ;
pa) @: 95-110. Jan. +9 1917.
5 seomoatto’ in. Aetinians. fou. Exp. Zoi, 22 ty: ut

: inians, ‘I our. Exp

'

"B (2) 72-78. Feb, iy WT.» Pe
“288. Cou, we Lie —"The. Reactions, of ee ‘ampelpphita, Loew io Gtavity, Cen-
Jour. Anim. ice 71-80, Jan., 1917.

a7, - Parken G. ay ‘the Renponsin 0 aa pastie to Gravy “Bros. Nat. Acad. on

. 2 (i) 381 y Aas
* Panne, G. TL, — Abiinian: poe. To D
: BE _

298. Ene, ASO. ! hore.

2. =atead. Prog Nat. Acad: Sci., e 1904-205 Mar., ‘1917.

94, Pora, P. H.—The encarta : Westiindisn Anitira into Berm” “Bail Mes.
ee 17-131, “May, 1917s,’ 4 F 4
a6, Vax re Ore ‘Ae Bie he Skin of. the ‘Catfish (Amiurus crbilouey 5 asa ‘Ree
: eri Jot we eit.

ety IIT:
The Reception of Sechaniea! 8% ail. :

4 (4): ‘AOR 89. vtecik
er biSuction i in the: ‘Ben

‘

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF
THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD
_COLLEGK.. < Continued: de 3

“> B00, PARRER, G. Hw The Activities a Conymorptis- Jour. Exp. Baitiy 24 2): 2808
. B81. -Noy., 1917.

$01, Sretesr, C. B.: ~The Means of Locomotion in i Plana. “ Proe. Nat. Kead., c
Sci., & (12):691-692,. Dee 1. 2.

"302, Ouustan, J: M.D. —The- -Regenoration of eeteriee Pieces: of Plainaria wedulater
AStudy in Polarity. Jour. Exp. Zodl., 2 (1)+ 157-176... Feb., 1918+.

808, ‘Hot, 8. —The Physiology of ‘Ascidia atra Lesacuzz. I. General Physiology.

304, IL. Sensory Physiology. Jour. Exp. Zoél., 25 a): 1229-299, Febs, 1918,

305., y, NCEE: —Id.- i The Blood uel Amer, Jéur een 45 ee 18187.

= ~ Feb., 1018, :

we-iliearistte. Broa: Nat. Acad: Sci., 4 (3): 58-80. —"
807, Watton, A. C.—The Odgenesis and-Early Embryology, “of Ascaris canis Werner.
Jour«.Morvh., $0 (2): : 6276603. — Mar., 1918, ~ man
- 308. Onmstup, J. M. D.— ~ Experimente. on the Nature ‘of ‘the Sense of Smell i in the?
al Common ‘Catfish, Amiurus nebulostis (Lesneur),.: “Amer. Tour: Physiol., 46
ca (6) 448-458. Alig., 2018. < ae
309. -Repried, A. C.—The “Physiology of the Malanoptiores ot the Hoimed. Tondy’
oe ‘Phrynosoma. Jour. Exp. Zoi, 26 (2), +276-383. July, 1918. -- aia
dour: Physiol,

310, BRooxs}.E. S.— Reactions ot Frogs, to~Heat and ‘Cold. Amer
- "46.5 1498-50L Aug. 1918 7 . ;
311, Cops, P. H.— Autonomous Responses of the bial Palps of Anodonta. Pres
Nab. Avad. Sci, & (8) : 234-285. “Aug., 1918.” - oo
312, IRWIN: M.—Thé Nature: of § Sensory’ Stimulation. by Salts, Amer, J our. Pry
ae ag (2): 265-277. Nov., 1918.’
313. _PaRKur, G.H.— The Rate of ‘Eransmission in the Nerve es of the Cosfentratek? :
7 Jour.- -Gén, Physiol; 1 (2) : 231-236. “Nov., 1918. are
B14 Sums A. J.=The Effect of Adrenin on the Pigment Migration in the- Melano-*
= © phoreé of th Skin and in the Pigment. Cells of the Retina. of the Frog: Jot
eg “Exp. Zoéls, 27 (3): 391-306. ‘Tan. 1919, i ae
315. Jorpan, H.— Concerning Reigsner’s* ‘Fiber i Peleosts. ‘Shite. Goimp. Neato,
Ee BO (2);217-227, 1pl. Feb. 1919-2 :
- 316. Parker, G. H. ~The ‘Org Organiza\ jon of Rehilla. Tour. Exp. Lost. are: 499
.. 607. “Feb, 1919, eae sy
817. Hunt, H. R.— -~ Regenerative Phenomena following the Reiioval of he: Digestiy
; o Tube and the Nerve Cord of Earthworms. Ball. Mas. Comp. adel -@2 (15)
Te 669-5814 pl. Apr.; 1919. . we ’
5 vee Davis,’ D: W.— As
- Verrill. Sout Exp. Zobl., 28 (2): ‘161-204, May, “119.
"819. _ PAREER, G.H.- +The Eifects of the past Winter on. the Ocgurrénce Sage
7, taeiae¥ erill Amer. Nat, 58 (8 ) 280-281. “May-June, 1919,
820, Minwice, D. E.—The Photic Réactions of the ‘Honey-Bee, Apis
-Jour. Exp, Zool, 29 (8): $343-425.° Nov., 1919.