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REGENERATION AND AUTOTOMY IN THE

BLACK WIDOW SPIDER,
Latrodectus variolus Walckenaer.

By
JOHN BROOKES RANDALL

A DISSERTATION PRESENTED TO THE GRADUATE COUJTCIL OF

THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGF.SE OF DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA
1979

J5
O

DEDICATION

This dissertation is dedicated to my mother, Norma B.
Randall, who taught me the values of study and striving to

REGENERATION AND AUTOTOMY IN THE

BLACK WIDOW SPIDER,
Latrodectus variolus Walckenaer.

By
JOHN BROOKES RANDALL

A DISSERTATION PRESENTED TO THE GRADUATE COU?fCIL OF

TPIE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY

ACKTIOWLEDGEMENTS

I would like to express my sincere appreciation to
Dr. H. L. Cromroy for his continual advice, encouragement
and friendship throughout the course of this study and for
furnishing me with the space and materials required to
complete this work.

I would especially like to thank Dr. Herbert Otaerlander
of the Insect At tract ants. Behavior and Basic Biology Research
Laboratory, USDA, Gainesville, Florida for his continual
counsel, encouragement and friendship and for his valuable
assistance in the preparation of the dissertation.

I would also like to acknowledge Dr. J. Nation and
Dr. J. Reiskind as members of my supervisory committee for
their advice and encouragement. I v/ould also like to thank
Dr. D. L. Silhacek, also of the USDA Gainesville lab, for
employing me in his laboratory and Dr. M. S. Mayer of the
same laboratory for his help in assessing some of the data
I collected.

My sincere thanks go to my parents, Mr. and Mrs. John
A. Randall of Millersville, Maryland, and to Col. and Mrs.
Charles Foreman of McLean, Virginia, for their continual
support and encouragement in seeing that ray family was
never without necessities.

Ill

Finally, I wish to thank my wife Carol who worked hard
at a not so desirable job so that I could complete my
graduate studies. Y/ithout her support, love and encourage-
ment this goal could never have been attained.

TABLE OF CONTENTS

Page

ACKNOWLEDGE?£ENTS iii

LIST OF TABLES . viii

LIST OF FIGURES ix

KEY TO SYMBOLS AND ABBREVIATIONS xix

ABSTRACT xiii

INTRODUCTION 1

LITERATURE REVIEW 3

Regeneration 3

Crustacea 4

Insecta . 4

Arachnlda 10

Autotomy 11

Crustacea 12

Insecta 13

Arachnida 13

L. Variolus and the Morphology of

Arachnid Palpal Organ and Legs 14

METHODS AND MATERIALS 20

L. variolus 20

Histology 21

Amputation and Ligature 21

Page

RESULTS 25

The Palpal Organ of L^ variolus 25

Development of the Papal Organ 25

Amputation of the Pre-penultimate Palp . . 30

Amputation at the mid-tarsus 30

Amputation at the tibia-tarsus joint . . 30

Amputation at the patella-tibia

joint 32

Amputation at the femur-patella

joint 35

Amputation at the mid-femur and at

the trochanter-f emur joint 35

Amputation at the coxa-trochanter

joint 36

Amputation of the Penultimate Palp .... 39

Amputation at the mid-tarsus 39

Amputation at the tibia-tarsus joint . . 39

Damage to the Palpal tarsus 39

Amputation at the patella-tibia joint. . 41

Amputation at the coxa-trochanter

joint 41

Ligature of Pre-penultimate and Penultimate

Palps 41

Ligature at mid-femur of Pre-penultimate

palp 41

Ligature at the tibia-tarsus joint of

Penultimate Palp 44

Ligature at mid-femur of Penultimate

Palp 44

Regeneration and Autotoray in Legs of L. variolus 44

Page

Amputation of the Legs 44

Amputation at the mid-telotarsus .... 44

Amputation at the mid-basitarsus .... 46

Amputation at the mid-tibia and at

the patella-tibia joint 46

Amputation at the femur-patella joint . . 48

Amputation at mid-femur 48

Am.putation at the trochanter-f emur joint. 50

Amputation at the coxa-trochanter joint . 50

Amputation at the Proximal Margin of

the Coxa 50

Localized Injury to the Femur 50

Ligature of the Legs 54

Ligature at the mid-basitarsus 54

Ligature at the mid-tibia 56

Ligature at the patella 56

Ligature at the mid- femur 58

External Force Applied to the Autotomy

Plane of the Leg 58

Summary of Results 58

DISCUSSION 63

Regeneration 63

Autotomy 68

APPENDIX 1 - Fixation, Dehydration and Embedding . , 74

APPENDIX 2 - Mallory's Triple Stain Technique ... 76

LITERATURE CITED 77

SUPPLEMENTARY BIBLIOGRAPHY 82

BIOGRAPHICAL SKETCH 85

vix

LIST OF TABLES

Table Page

Summary of the amputation experiments performed

on pre-penultimate male Lw_ variolus palps .... 38

Summary of the amputation experiments performed

on penultimate male L^ variolus palps ^^

Summary of ligature experiments performed on
the palps of pre-penultimate and penultimate
male L_^ variolus 45

Summary of the amputation experiments perfonned

on the legs of L^ variolus 53

Summary of ligature and external pressure experi-
ments performed on the legs of L. variolus . ... 60

Vlll

LIST OF FIGURES

Figure Page

1 The developmental gradient model for
regeneration and duplication 8

2 The polar coordinate model for regener-
ation 9

3 Schematic diagram of the autotomy mechanism

of spiders 15

4 Comparative morphology of the spider leg

and palp 15

5 The development of the male palpal organ
and identification of some of the major

parts of the adult organ 18

6 Restraint apparatus used in amputation and
ligation experiments 23

7 Ligature in place on the leg of L^ variolus 23

8 Pre-penultimate palp of a male L_^ variolus 26

9 Early proliferation of pretarsal primordia 26

10 Pretarsal cells at 48 - 72 hours of develop-
ment 27

11 Penultimate palp of a male L_^ variolus ... 27

12 Differentiation of the developing palpal
organ at 24 - 36 hours into the penultimate
instar 28

13 Differentiation of the developing palpal
organ at 48 - 72 hours into the penultimate
instar 28

14 Differentiation of the developing palpal
organ approximately four days prior to the

adult molt 29

Figure Page

15 Embolus of the developing palpal organ

visible through the tarsal cuticle 29

16 Results of amputation of pre-penultiraate

palp at mid-tarsus 31

17 Results of amputation of the pre-penultimate
palp at the tibia-tarsus joint 31

18 Histology of regenerate palp following ampu-
tation at the tibia-tarsus joint 33

19 Results of amputation of the pre-penultiraate
palp at the patella-tibia joint 33

20 Histology of regenerate palp following ampu-
tation at the patella-tibia joint 34

21 Results of amputation of the pre-penultimate
palp at the femur patella-joint 37

22 Results of amputation of the pre-penultimate
palp at the mid-femur and trochanter- femur

joint 37

23 Results of amputation of the pre-penultimate
palp at the coxa-trochanter joint 37

24 Results of amputation of the penultimate palp

at the mid-tarsus 40

25 Eesults of amputation of the penultimate palp

at the tibia-tarsus joint 40

26 Results of damage (puncture) to the tarsus of

the penultimate palp 40

27 Results of amputation of the penultimate palp

at the patella-tibia joint 42

28 Results of amputation of the penultimate palp

at the coxa-trochanter joint 42

29 Results of amputation of the leg at the mid-
telotarsus 47

30 Results of amputation of the leg at the mid-
basitarsus 47

Figure Page

31 Results of amputation of the leg at the mid-
tibia and at the patella-tibia joint .... 47

32 Results of amputation of the leg at the femur-
patella joint 49

33 Results of amputation of the leg at the mid-
femur 49

34 Results of amputation of the leg at the
trochanter- femur joint 49

35 Results of amputation of the leg at the coxa-
trochanter joint 51

36 Results of amputation of the leg at the
proximal margin of the coxa 51

37 Results of localized injury to the femur of

the leg 55

38 Results of ligation of the leg at the mid-
basitarsus 57

39 Results of ligation of the leg at the mid-
tibia 57

40 Results of ligation of the leg at the patella 59

41 Results of ligation of the leg at the mid-
femur 59

42 Comparison of the regenerative capacities

of the pre-penultimate and penultimate palps

of the male L^ variolus 66

43 Healing of the wound produced by amputation of
the pre-penultimate palp at the tibia-tarsus
joint 69

44 The open wound of an autotomized leg after
localized injury to the femur of the leg . . 69

45 A comparison of the autotomy, healing and
regeneration of the legs injured by amputa-
tion and ligation 70

46 Histology of the telotarsus of the leg of

L. variolus showing the leg nerve present. . 70

KEY TO SYMBOLS AND ABBREVIATIONS

alveolus

btar

basitarsus

conductor

coxa

Cx. ms

coxal muscle

cymbiura

D. lb

dorsal lobe

embolus

femur

fundus

Haem

haematodocha (basal)

Inv

invagination

M.a

median apophysis

nerve

Pat

patella

Ptar

pretarsus

R.s

receptaculum seminis

Scl

sclerite

Tar

tarsus

ttar

telotarsus

T.a

terminal apophysis

Tib

tibia

Trochanter

V.lb ventral lobe
amputation

ligation

Xll

Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

REGENERATION AND AUTOTOMY IN THE BLACK
WIDOW SPIDER, Latrodectus variolus
Walckenaer

JOHN BROOKES RANDALL

August 1979

Chairman: Dr. Harvey L. Cromroy

Major Department: Entomology and Nematology

The restoration of lost body parts by regeneration has
been extensively investigated in arthropods. Crustaceans,
insects and to a lesser degree arachnids have been utilized
to study this phenomenon. The loss of an appendage most
readily occurs at a predetermined plane of weakness, termed
the autotomy plane, as a mechanism of escape or severence of
a' badly damaged limb. The mechanism of autotomy is believed
to be initiated by a nervous reflex. Past researchers state
that the capacity for arthropod regeneration is greatest
at the autotomy plane.

Amputation and ligature of the developing male palpal
organ and the legs v/ere used to determine whether regeneration
occurring in the black widow spider, Latrodectus variolus
Walckenaer complied with the developmental gradient of regen-
eration. The occurrence of autotomy in this species was

also documented.

xiii

The ability of the pre-penultimate palp to regenerate
and subsequently produce a normal adult palpal organ was
confined to injury to the distal portion of the palp. Ampu-
tation of more proximal segments of the male palp during the
pre-penultimate stage did not result in normal adult palps
two molts later. Amputation of or severe damage to the tibia
and tarsus of the penultimate male palp most often resulted
m the death of the spider. No regeneration occurred follow-
ing amputation or ligature of penultimate palps.

Amputation indicated the most proximal point from which
regeneration of the leg could occur was the mid-point of the
femior. Proximal to that point no regeneration was observed.
Autotomy following amputation was not observed. The regenera-
tion observed in the palps and legs of L^ variolus complied
with the developmental gradient and polar coordinate models
for regeneration.

Ligature of the legs resulted in autotomy when applied
at and proximal to the mid-point of the tibia, increasing in
frequency as more proximal segments were ligatured. Autotomy
always occurred at the coxa-trochanter joint. No regeneration
of the legs occurred following autotomy.

The evidence strongly suggests that autotomy in the legs
was initiated by a wound factor (currently hypothetical)
released after injury and the dose of which may be related to
the size and duration of the wound.

XIV

INTRODUCTION

In their evolution from annelid-like ancestors arthropods
had to sacrifice some advantages in order to become more
specialized and complex. Although their greater complexity
does not allow for the regeneration of large body parts, such
as an entire head, arthropods have retained the ability to
regenerate appendages. When arthropods gained the protection
of an exoskeleton it became necessary for them to molt in
order to grow. Likewise, molting was required for arthropod
regeneration to occur. The rigid exoskeleton, clearly segment-
ed, provides for qualitative and quantitative measurement of
regeneration. For this reason arthropods, especially crusta-
ceans, insects and to a lesser extent the arachnids, have
been the subject of considerable research into the mysteries
of regeneration.

Unlike the Crustacea that continue to grow and molt after
reaching maturity, insects, once sexually mature, lose the
ability to molt and thereby their ability to regenerate lost
parts. The majority of spiders, like insects, cease molting
after maturity is attained. Exceptions to this include the
mygalomorph spiders (i.e. tarantulas) that continue to molt
after maturation and can live up to 25 years.

The black widovvr spider has been the subject of much
study in past years. A species of black widow spider,
Latrodectus variolus Walckenaer, was used in this investiga-
tion to establish the regenerative capacitites of the develop-
ing male palpal organ and legs. The occurrence of autotomy
in this species was also studied. The results establish
three alternatives, besides death, to the injury exhibited
by L_^ variolus; healing with no regeneration, regeneration or
autotomy.

The following literature review provides background
information on arthropod regeneration and autotomy as well
as on the development of the palpal organ of a male black
widow spider.

LITERATURE REVIEW

Regeneration
Regeneration, the restoration of lost parts, has been
described by many authors. Goss (1965) views regeneration
as a physiological process, not sinply anatomical growth,
with the primary objective of re-establishing the functional
efficiency of the organism. Thus, regeneration is stimulated
by the physiological demands for increased function caused by
the loss of a body part. Goss defines qualitative regenera-
tion as that process which occurs to replace a lost limb, as
this is the only way efficiency can be restored in a struc-
ture that has a single function. Quantitative regeneration
is the method by which compound organs, such as a liver,
would be restored.

Wolpert (1974) considers regeneration as the re-establish-
ment of the positional field of cells followed by the reinter-
preting of positional values. This can be attained by either
of two methods. (1) Epimorphosis involves growth from the
cut surface of the wound to provide new positional values for
the regenerating portion. (2) Morphallaxis establishes a new
boundary region at the cut surface and new positional values
are assigned within the existing adjacent tissues. Morphall-
axis does not involve growth.

Crustacea

Crustaceans have been utilized extensively in the study
of regeneration (Agar, 1930; Bliss, 1960; Emmel , 1910;
Needham, 1945, 1947, 1949, 1950, 1953; Paul, 1914; Wilson,
1903; Wood and Wood, 1932). Crabs, lobsters and crayfish
have been examined extensively because of their convenient
size, availability, and possession of a preformed breakage
plane (Bliss, 1960). With the possible exception of mouth-
parts, decapods seem to be able to regenerate all types of
appendages. It is believed that in Crustacea the peripheral
nerve supply in the region of amputation exerts a local
effect favoring limb regeneration. This, coupled with neuro-
secretory hormones which inhibit the molt-promoting Y-organs
are responsible together for the regenerative capacity in
these animals (Bliss, 1960).

Insecta

Among the insects used in regeneration experimentation,
cockroaches have been studied most extensively. Bohn (1965,
1972, 1974a, 1974b, 1974c) used Leucophaea maderae in experi-
ments which indicated that the integumental tissues that
separate adjacent legs were required for the regeneration of
the leg. Regeneration of a leg occurred only when both the
basal sclerites anterior to and a membraneous area posterior
to the coxa were in contact with each other. Bohn confirmed
these results through transplantation experiments (Bohn, 1974b)
Bohn (1965) found that a V-shaped wedge cut from the tibia of

Leucophaea resulted in the next instar developing a lateral
regenerate at the site of injury.

Scientists working on different insects described vari-
ous proximal limits for leg regeneration. Penzlin (1963)
(Periplaneta) reported regeneration after removal of most of
the basal sclerites (episternum and epimeron) . Bulliere
(1967) and Urvoy (1963) (Blabera craniifer Burm.) found the
proximal limit of regeneration between the coxa and trochantin
and praecoxa and trochantin respectively.

Luscher (1948) reported regeneration of the leg of
Rhodnius occurring as far back as the coxa-trochanter joint.
In 1933 Bodenstein reported regeneration after removing the
entire leg and surrounding tissues in larval Vanessa urticae
Raupen (Lepidoptera) . Bodenstein (1955) not only discovered
that Periplaneta americana could regenerate the entire leg
after amputation at the trochanter-f eraur joint, but also
found that ecdysone was required for initiating and sustaining
the progression of regeneration. Adult Periplaneta could be
made to regenerate through parabiotic fusion with nymphs and
by transplantation of active prothoracic glands. It was
Bodenstein 's feeling that "wound factors" produced at the
site and time of injury played a minor role, if any, in the
initiation of regeneration. Needhara (1947) argues that a
wound factor may in fact reduce the regenerative power since
after autotomy of limbs in the crustacean Asellus aquaticus
if the remaining tissues are mechanically damaged there is a
reduction in the animal's regenerative capacity.

O'Farrell and Stock (1953) investigated regeneration of
the metathoracic leg of Blattella germanica , and found that
v/hen the leg was amputated at the proximal autotomy plane
(between the trochanter and femur) either a completely differ-
entiated regenerate or an undifferentiated papilla resulted,
a complete regenerate appeared at the second molt following
amputation. They also described a "critical period" during
the first instar before which amputation resulted in a com-
plete regenerate with a delay in the first ecdysis following
surgery and after which the papilla was produced with no
delay in ecdysis. The ability of B_^ germanica to regenerate
a complete leg persisted until the last molt. Repeated
regeneration of the same leg prolonged development and
caused additional molts but the adults resulting from such
supermolts were normal in size and appearance. When reared
at 25 C, repeated regeneration of B_^ germanica initiated
early in development resulted in more supermolts than if
initiated later. Most of the experimental insects reared
at 30 C metamorphosed without supermolts.

Regeneration in insects has also been studied through
experimentation on the imaginal discs of developing larvae.
Bryant (1971) performed ±n situ experiments bisecting the leg
discs of Drosophila melanogaster . He found that the upper
portion of a bisected disc, still attached to the larval
epidermis, regenerated; whereas the lower half of the disc,
unattached from the larval epidermis, diiplicated itself.

Partial bisection of leg discs resulted in branched
legs where one branch was complete and the other branch a

double half. Bryant interpreted these results to mean that
regeneration occurred from one cut edge and duplication from
the other. From this work Bryant proposed a gradient of
developmental capacity and its response to bisection (Fig. 1) .

Later Bryant (1975) found that when an imaginal disc was
cut into three pieces those fragments with their cut edge
facing away from the center of the disc underwent regenera-
tion, while fragments with their cut edge facing toward the
center of the disc underwent duplication. The presence of the
center of the disc was not a prerequisite for regeneration.
Fragments with two cut edges on the same side of the center
would exhibit regeneration at one edge and duplication at
the other.

French et al . (1976) proposed the polar coordinate
model for regeneration based on information from cockroach
and amphibian limb regeneration and insect imaginal disc
regeneration. Their model is a two-dimensional system allow-
ing the assignment of specific positional information to an
epimorphic field. One coordinate defines the circumferential
position of a cell by twelve meridinal points numbered clock-
wise one to twelve. Letters A to E define the proximal-
distal position of a cell. Proximal structures are at the
periphery and distal structures are at the center of the
model (Fig. 2).

They also proposed two rules for the behavior of cells
in an epimorphic field. The rule of intercalation states
that when normally non-adjacent positional values in either

PROX.

DISTAL

Bissection

P c

Growth

E E.

Regeneration

Duplication

Fig. 1. The developmental gradient model for regeneration
and duplication (Bryant, 1971).

Fig. 2. The polar coordinate model for regeneration (French
et al. , 1976).

the circular or radial sequence come into contact in a graft
or through wound healing, growth occurs at that junction
until the cells with intermediate positional values have
been intercalated.

The second is the complete circle rule for distal trans-
plantation. The entire circular sequence at a particular
level may undergo distal transplantation to produce cells
with all the more central (distal) positional values. This
rule pertains to Bryant's gradient of developmental capacity
(Fig. 1) and means that when amputation occurs along the
proximal-distal sequence of positional values the proximal
level remaining can regenerate only those positional values
distal to it .

Arachnida

Regeneration in arachnids has been little studied
(Bonnet, 1930; Friedrich, 1906; Schultz, 1898; Vachon, 1941;
Wagner, 1887). The most extensive of these studies was car-
ried out by Bonnet working on Dolomedes f imbriatus (Clerck)
(Pisauridae) . Bonnet (1930) reported that D. f imbriatus
could regenerate from one to all eight legs, taking three
molts to re-establish normal size.

Bonnet also performed regeneration experiments on devel-
oping male palps and concluded that if the loss of part or
all of a palp occurred no later than the preantepenultimate
instar (three more molts before maturation) the male could
fully regenerate the palp. Palps injured or lost later than

the preantepenultimate stage would not regenerate completely.
When injured at the prepenultimate stage the palps were some-
times perfectly formed at maturation but were too short so
that the animals could not come to normal copulation.

Vachon (1941) reported that the leg segments of the same
regenerating leg were not necessarily all at the same stage,
distal segments being "older" than proximal ones.

Autotomy

Several terms have been used to describe the loss of an
arthropod limb; they include: 1) autotomy, 2) autospasy and
3) autotilly (Bliss, 1960). Autotomy is the ability of an
animal to cast off its own appendage at a pre-determined
breakage plane by a well developed, usually unisegmental
reflex. Autospasy has been defined as the separation of a
limb at a predetermined plane of weakness when the limb is
subjected to force by an outside agent against the resistance
provided by the animal's weight or efforts to escape. Auto-
tilly is the severence of the limb at a predetermined plane
of weakness through use of the mouthparts, claws, or legs of
the animal itself.

The point common to all three definitions is the "pre-
determined plane of weakness," also termed breaking joint,
autotomy plane, plane of least resistance, and locus of weak-
ness or separation (Bliss, 1960).

Injury or amputation distal to the plane of weakness
often causes the entire limb to detach. In most arthropods

no muscles cross the autotomy plane (Needham, 1965), An
exception to this was described by Parry (1957) where the
M. Flexor femoris longus of the spider Tegenaria atrica Koch
(Agelenidae) passes from the coxa, through the trochanter to
attach to the femur. The autotomy plane of T\_ atrica is at
the coxa-trochanter joint.

Autotomy occurs as the result of a nervous reflex
initiated by injury to the limb (Goss, 1965). Goss also
stated that the capacity for regeneration of lost appendages
in arthropods is greatest at the autotomic breakage plane.

Crustacea

Some crustaceans possess an autotomy plane but no reflex
of autotomy. In others (i.e. Homarus americanus) autotomy
only occurs in the first pair of thoracic legs or chelae.
Autospasy and autotilly may occur in the other limbs as the
plane of weakness exists but the autotomy reflex is absent
in those legs (Wood and Wood, 1932). When Wood and Wood
studied 15 species of crabs they found autotomy exhibited in
all five pairs of legs.

The stimulus for autotomy may occur when injury is sus-
tained to an appendage distal to the plane of weakness.
Hodge (1956) demonstrated in the crab Gecarcinus lateralis
that autotomy never resulted from injury to the dactyl, the
most distal segment of the walking leg, but did occur with
greater frequency as more proximal segments were injured.
This was also demonstrated by Needham (1947) for Asellus
aquaticus and on several species of Brachyura (Wood and Wood,

1932). This may be related to the fact that the leg nerve
does not extend beyond the proximal area of the propus, the
next proximal segment to the dactyl (Bliss, 1960).

Bliss also reported that acetylcholine reduces the fre-
quency of autotomy when injected into a crustacean and that
acetylcholine antagonists (i.e. atropine) facilitate autotomy.

Insecta

O'Farrell and Stock (1953) found regeneration when the
leg of B^ germanica was removed at the autotomy plane, between
the trochanter and femur. The same plane of weakness has been
described for mantids, phasmids, and grasshoppers (Bliss, 1960)
A second locus of separation was reported at the tibia-tarsus
joint of B^ germanica by Woodruff (1937). A true autotomy
reflex was described for Achaeta domesticus L. by Brousse-
Gaury (1958).

Autotomy is even well developed in Tipulidae and Opiliones
(arachnida) where regeneration is impossible (Needham, 1965).
The ability to escape has value regardless of the ability to
replace the appendage lost in escape.

Arachnida

Autotomy has been examined in spiders (Bonnet, 1930;
Parry, 1957; Wood, 1926). Unlike crustaceans and insects,
spiders autotomize their legs at a functional joint, the coxa-
trochanter joint (Parry, 1957). Bliss (1960) stated that
among the true arachnids, including the spiders, there is
autospasy but not autotomy. Wood and Wood (1932) reported the

absence of a plane of weakness in scorpions, ticks and
Liraulus .

Wood (1926) after a detailed morphological study of the
exoskeleton and musculature of scorpions, harvestman, and
twelve species of spiders, reported no autotomizing mechanism
existed in those animals. Severence of the legs did, however,
occur at a point in the limb directly correlated with a
definite structural weakness in the exoskeleton and muscula-
ture. Wood reported that the spider itself removed the injured
leg by grasping it with its raouthparts (autotilly) and conclud-
ed that autotomy as an automatic reflex did not exist in
arachnids. Parry (1957) reported findings contrary to Wood's
1926 report when he described the mechanism by which Tegenaria
atrica autotomizes its legs. Parry found that in T_^ atrica
the coxal muscles were all inserted onto a ring of sclerites
that fit into a groove in the proximal rim of the trochanter.
The joint fractures when the coxal muscles contract pulling
the articular membrane proximally also causing the sclerites
to converge leaving only a small hole that rapidly seals with
clotting blood (Fig. 3).

L. variolus and the Morphology
of Arachnid Legs and Palpal Organ

The biology of the black widow spider has been well

documented (Baerg, 1923; Bhatnagar and Rempel, 1962; Burt,

1935; Chamberlin and Ivie, 1935; Deevey, 1949; Hagstrum, 1968;

Jellison and Philip, 1935; Kaston, 1937, 1954, 1963, 1968,

1970; Lawson, 1933; Levi, 1958; McCrone , 1968; Rempel, 1957;

LEG

INTACT

'>.■■ ::i!-^irn^7tmn^ ..yw7^7TC^7roTn_^fT-.Trnrr--rr; 'Drilrjrrr,'

Cx.?/!s Cx Scl Tr

AUTOTOMY

ii^^l^i

Blood clot

Fig. 3. Schematic diagram of the autotomy mechanism in spiders

. 1. u

'aiotarsus

PALP

Fig. 4. Comparative morphology of the spider leg and palp,

■A

Ross and Smith, 1979). There are three species of North
American black widow spider: Latrodectus mactans (Fabr.)
and L^ variolus Walckenaer in the eastern U. S. and only
L. hesperus Chamberlin and Ivie in the western U. S.

The adult female L^ variolus has a black cephalothorax
and legs. There is a row or mid-dorsal red spots on the
abdomen and three pairs of diagonal white stripes on each
side with a narrow white stripe encircling the anterior dorsum
of the abdomen. The hourglass mark on the ventarl abdomen is
divided, the two halves seaparated (Kaston, 1970). In some
cases half or the entire hourglass mark may be completely
absent (Kaston, 1954). The male L^ variolus is colored like
the female but with broader white stripes. Female black
widows may be as much as 160 times larger than the males
by weight (Kaston, 1970).

The range for the number of days spent in each instar
for L^ variolus as reported by Kaston (1970) for instars one
through five are: 1 to 33, 5 to 30, 6 to 48, 6 to 76, and 7
to 76,124 (sic) days respectively.

The pedipalp of a spider is morphologically similar to
the spider leg with the exception that the tarsus of the leg
is subdivided into a long basal part called the basitarsus
(also metatarsus of 1-tar) and a shorter distal part called
the telotarsus (also tarsus or 2-tar) (Fig. 4). The tarsal
subunits of the leg are not true segments as exhibited by the
consistent absence of interconnecting muscles (Snodgrass, 1965)

The development of the male palpal organ of L^ curacavien-
sis was described by Bhatnagar and Rempel (1962). Kaston

(1970) disputes the species Bhatnagar and Rempel studied was
L. curacaviensis but was instead L_^ hesperus .

The pedipalps of newly emerged male and female spiders
are indistinguishable (Fig. 5A). The development of the
papal organ, the male copulatory organ, is first recognizable
when the palpal tarsus becomes slightly swollen (Fig. 5B) .
The swelling usually first appears in the antepenultimate
(pre-penultimate) instar but has been observed as early as
the preantepenultiraate instar. When the male reaches the
penultimate instar, the palps become very large and bulbous
(Fig. 5C). Inside the bulbous palp the palpal organ is
developing.

Like insect imaginal discs the origin of the palpal organ
is the hypodermis (Bhatnagar and Rempel, 1962).

At the first swelling of the male palp the cells tha.t
give rise to the pretarsus increase in size and number and
form a mass having dorsal and ventral lobes. During this
stage the muscle tendons associated with the tarsal claws
lose their connections and the new claw secreted by hypodermal
cells is immobile and passive. The large number of blood
cells in the tarsus may indicate the swelling was caused by
hydrostatic pressure.

With the next molt the penultimate palp, now extremely
bulbous, continues the internal morphogenesis of the copula-
tory organ. The receptaculum seminis, the sperm storage
tube consisting of the fundus, reservoir and ejaculatory duct,
can be seen as an invagination of the ventral lobe. Later in

fc#l

Tarm. Apophysis

Mad. Apophysis

Conductor >•

EtTibolus

Fig. 5. The development of the male palpal organ and identi-
fication of some of the major parts of the adult organ.

the instar the base of the developing organ is joined to the
tarsus by a small neck of cells destined to become the basal
haematodocha. The haematodocha is a folded membrane within
the alveolus of the mature palp that forms an articulation
between the cymbium and the sclerotized portion of the genital
bulb and becomes distended during copulation due to increased
hemolym.ph pressure. The formation of the small neck of cells
represents the pretarsus becoming withdrawn into the tarsus.
The tarsus will develop into the cymbium which holds the
receptaculura seminis and its accessory sclerties within the
alveolus. Toward the end of the penultimate instar the devel-
oping palpal organ can be seen through the tarsal wall. At
the final molt the adult palpal organ appears (Fig. 5D) .

Based on the above information experimental objectives
for the present research were established for investigation
of regeneration and autotoray in the legs and palpal organ of
L- variolas . Experiments were designed to determine and
compare the regenerative capacities and autotomic responses
of pre-penultimate and penultimate male palps resulting from
injury by amputation and ligation. Another series of experi-
ments was performed to discover the regenerative capacity and
autotomic responses of the legs of immature L_^ variolus
resulting from injury by amputation, ligature and local seg-
mental injury. The results of the above experiments would
then allow for the comparison of the regenerative capacities
of the developing palpal organ and legs since these parts of
a spider are morphologically homologous.

METHODS AND MATERIALS

L. variolus
Latrodectus variolus was chosen as the subject of experi-
mentation because of its availability, and the fact that of
the three North American species its newly emerged spiderlings
are the largest and they hatch and emerge in the shortest
time (Kaston, 1970). Adult female L^ variolus were acquired
from Tempe, Arizona, and maintained in the laboratory on a
diet of cabbage looper (Trichoplusia ni (Hubner)) larvae.
Egg sacs constructed by the adult females were removed to
separate containers until the emergence of young. The newly
emerged spiderlings, considered to be in the second instar,
were separated into numbered, 35 X 10 mm polystyrene culture
dishes. Spiderlings were maintained at room temperature and
fed adult Drosophila melanogaster . Exuvia were removed from
the rearing containers following each molt thus insuring
against mistakes in instar identification. Pre-penultimate
and penultimate males, third and fourth instar respectively,
identified by the noticable swelling of the palpal tarsus
were separated from the primary rearing colony for experimenta-
tion. Fourth and fifth instar female L_^ variolus were used
primarily for leg regeneration experiments.

Histology
Spiders used in histological studies were fixed in
alcoholic Bouin's fixative for 4 to 24 hours before being
transferred to the dehydration series. Dehydration was follow-
ed by infiltration and embedding in paraffin (Appendix 1).
Embedded material was sectioned on a rotary microtome at six
to ten microns, mounted on glass slides and stained using
Mallory's Triple stain technique (Appendix 2). Slides were
then examined and photographed through a compound microscope.

Amputation and Ligature
Amputation and ligature procedures were carried out with
the aid of a dissecting microscope. Due to the possible
effects of anesthesia on the postoperative physiology of the
immature spiders no anesthesia was used. Unanesthetized
spiders were placed in an apparatus I fabricated (Fig. 6)
specifically to restrain while not damaging the spiders for
the duration of the procedures. The apparatus was designed
to hold the spider in a foam rubber sandwich with the appen-
dages to be opera.ted on exposed. The foam rubber allowed
the fragile spiders to be firmly held without injury. From
control studies it was determined that holding the spiders
in the apparatus for as long as three minutes (twice the
upper limit for actual procedures) in no way altered the
development of the young L_^ variolus. It took 40 - 90
seconds for the amputation and ligature procedures, including -■
the time for removal and return of the spider to its rearing
container.

Pre-penultimate and penultimate male palps were ampu-
tated at various points from the mid-tarsus (most distal)
to the coxa-trochanter joint (most proximal). Likewise,
one of the first pair of legs was cut at various points from
the mid-telotarsus (most distal) to the proximal margin of
the coxa (most proximal). Amputations and other cuts were
made with microscissors with the exception of cuts made at
the proximal margin of the coxa in which case specially
fabricated microscalpels were used.

In all cases only one palp or leg was injured leaving
the corresponding appendage to develop normally to serve as
a standard with which to compare the results of the operations.
Comparisons were made only v>rith the uninjured corresponding
appendage of the same animal.

Wounds made during amputation were not sealed with any
foreign substance; healing was left up to the spiders.

Ligatures were made with sterile, 7-0 Ethicon braided
silk suturing thread. Overhand knots were pre-tied with
forceps leaving a loop approximately one to two millimeters
in diameter. V?ith a spider in the restraint the loop was
slipped over the leg, positioned and tightened (Fig. 7).
The free ends were trimmed close to the knot v/ith micro-
scissors. Ligatures were placed at various points on the leg
from the mid-basitarsus (most distal) to the mid-femur (most
proximal) and at the mid-femur of pre-penultimate and penul-
timate palps and at the tibia-tarsus joint of penultimate
palps .

Insect Pin

Petri Dish^, Cr

Foam Rubber

^Paraffin

Fig. 6. Restraint apparatus used in amputation and lipation
experiments. "

'■'^i

Fig. 7. Ligature in place on the leg of L. variolus

The possibility existed that the manipulation of the
spiders during amputation and ligature might also cause
injury at other parts of the leg, especially at the plane
of weakness. The legs were pulled with forceps in a pre-
liminary experiment to establish the plane of weakness in
the leg and palps (coxa-trochanter joint) and to simulate
autotomy at that point. An experiment was conducted to tax
the coxa-trochanter joint by pulling steadily on the leg
until the articulating membrane between the coxa and trochan-
ter split releasing some hemolymph. The leak in the membrane
at that point and at no other joint along the leg, indicated
that the autotomy plane had been taxed beyond normal limits
while leaving the leg intact.

Bohn (1965) had removed a V-shaped wedge of tissue from
the tibia of L_^ maderae resulting in a leg regenerating from
the site of injury. A similar experiment was performed on
L. variolus by removal of a section of tissue from the femur
of a leg.

RESULTS

The Palpal Organ of L. variolus
The pre-penult imate and penultimate palps of L^ variolus
males were sectioned to establish the morphogenesis of
normally developing palps and thereby set a standard with
which to compare the results of subsequent amputation and
regeneration of the palps.

Development of the Palpal Organ

The internal morphogenesis of the palpal organ of L.
variolus is very similar to that described for L^ curacavien-
sis (or L^ hesperus) by Bhatnagar and Rerapel (1962).

The pre-penult imate palp exhibited a slight swelling,
most pronounced at the tibia-tarsus joint (Fig. 8). At this
stage the palp contains the pretarsal primordia now rapidly
proliferating into the dorsal and ventral lobes of the devel-
oping organ (Fig. 9). The cell mass changes configuration
very little after 48 to 72 hours of development (Fig. 10).

After the next molt the slightly swollen pre-penult imate
palp becomes extremely bulbous (Fig. 11). With the onset of
the penultimate instar morphogenesis increases so that the
developing palpal structures can be identified (Figs. 12 and
13). Near the end of the penultimate instar genital bulb
structures are well differentiated within the palp (Fig. 14)

•IM

^^;^''

Fig. 8. Pre-penultiraate palp of a male L. variolus.

Piar y.ib Tar

Fig. 9. Early proliferation of pretarsal primordi

/ " "'

Ptar y.ib

Fig. 10. Pretarsal cells 4S-72 hours of development

^^^mm

Fig. 11. Penultimate palp of a nale L. variolus.

-W^Tt

■.••:/

Fig. 12. Differentiation of the developing palpal organ at
24-36 hours into the penultimate instar.

W'-'-»>r.'

M.a

Fig. 13. Differentiation of the developing palpal organ at
48-72 hours into the penultimate instar.

•,-■' t

Fig. 14. Differentiation of the developing palpal organ
approximately four days prior to the adult molt.

^-^

Tar-

Fig. 15. Embolus of the developing palpal organ visible
through the tarsal cuticle.

and can be seen through the cuticle of the tarsus (Fig. 15).

These results form the morphological basis by which
the histology of regenerate palps resulting from the amputa-
tion experiments to follow can be compared.

Am.putation of pre-penultimate palps

Pre-penultimate palps were amputated at various points
to discover if palps injured during that stage would regener-
ate to normal penultimate palps and subsequently produce
normal adult palps.

Amputation at the mid-tarsus

In 18 pre-penultimate male L_^ variolus a palp was cut
at the mid-point of the tarsus, eliminating the developing
tissue of the developing palpal organ. Amputations v/ere made
when the spiders were an average of 30 days (range = 12-55
days) into the instar. It took an average 15 (range = 9-19)
post-amputation days for the spiders to molt to the next
instar. All of the specimens molted to the next instar and
exhibited normal appearing penultimate palps. At the time of
this report six had molted to the adult stage with normal
adult palps (Fig. 16).

Amputation at the tibia-tarsus joint

The entire tarsus of one palp was removed from each of
18 spiders. The spiders were an average 28 days (range = 3-55
days) into the instar at amputation. The spiders required an
average of 22 (range = 14-39) post-amputation days to molt.

Fig. 16. Results of amputation of pre-penult imate palp at
mid-tarsus .

Fig. 17. Results of amputation of the pre-penultimate palp
at the tibia-tarsus joint.

One specimen displayed no regeneration after the post-amputa-
tion molt having only the coxa of the injured palp remaining.
It is interesting that this spider spent the longest post-
amputation period (39 days) before molting yet did not regen-
erate.

The 17 remaining spiders exhibited imperfect regeneration
in several modifications of the same general regenerate;
the tarsus had regenerated much smaller than the normal
corresponding penultimate palp. Examples of the different
regenerates are shown in Figure 17. Histological examination
of the regenerates indicated that the pretarsal primordia
had been re-established and morphogenesis of the palpal organ
was occurring but on a much smaller scale (Fig. 18). None
of the eight spiders molting to the adult stage displayed
any further regeneration of the injured palp.

Amputation at the patella-tibia joint

By amputating at the patella-tibia joint the entire
tibia and tarsus were removed from one palp of 25 pre-penulti-
raate male L^ variolus an average of 23 days (range = 2-63 days)
into the instar. These spiders took an average of nine (range =
5-16) post- amputation days to molt to the penultimate instar.
The regenerates from this experiment were similar in appear-
ance to those of the preceding experiment. In 18 cases . the
regenerate appeared as a miniature penultimate palp one-third
to one-fourth the size of the corresponding normal palp (Fig.
19). In six cases the regenerate was a small bud distal to

&i.C

D.lb

Fig. 18. Histology of regenerate palp following amputation
at the tibia-tarsus joint.

essnerats

Fig. 19. Results of amputation of the pre-penultimate palp
at the patella-tibia joint.

Haem

Fig. 20. Histology of regenerate palp following amputation
at the patella-tibia joint.

the palpal patella. One spider exhibited no regeneration
having only the coxa of the injured palp remaining.

One specimen exhibiting the distal bud regenerate
molted to a second penultimate stage where the uninjured
palp remained unchanged and the regenerate palp had shrunk
in size from the previous penultimate instar.

None of the eight spiders molting to the adult stage
exhibited a normal palp following amputation of the tibia
and tarsus during the pre-penultimate stage.

Again, histological examination of the regenerated
palps indicated that morphogenesis of the palpal organ had
been re-established but the developing organ was much smaller
than the normal palp of the same age (Fig. 20).

Amputation at the femur-patella joint

In twelve spiders the palp was amputated at the femur-
patella joint at an average of 37 (range = 1-47) days into
the instar. The spiders molted to the next instar in an
average of 20 (18-21) days following amputation. Nine
specimens displayed only healing of the femur. The remaining
three spiders exhibited regeneration in the form of a small
bulb (Fig. 21) attached to the distal end of the femur.

Amputation at the mid-femur and Trochanter-f emur joint

In 14 pre-penultimate male L_^ variolus the palpal femur
was severed at its mid-point. In ten other specimens of the
same stage one palp was amputated at the trochanter-^f emur

joint. One specimen from the group cut at the mid-femur
died three days after amputation without molting. Amputations
were made an average of 24 days (range = 5-55 days) into the
instar and the 23 survivors took an average 20 (range = 5-47)
post-amputation days to molt to the penultimate instar.

Only three of the spiders (two from the trochanter-
femur cut and one from the mid-femur cut) displayed any
regeneration. The regenerates consisted of only the coxa,
trochanter and femur. The regenerate femurs were one-third
the size of their normal counterparts (Fig. 22). The remain-
ing 20 specimens, upon molting to the penultimate stage, had
only the coxa and trochanter of the injured palp present and
a norm.al palp in the corresponding position.

Amputation at the coxa-trochanter joint

Of the 16 pre-penultimate male L^ variolus used in this
experiment ten had one palp cut at the coxa-trochanter joint
and six had both palps removed by pulling with f oreceps .
The palps removed by pulling all severed at the coxa-trochanter
joint, establishing the plane of weakness for the palp.

All sixteen specimens molted to the next instar with no
regeneration of injured palps. Only the coxa of each injured
palp, whether cut or pulled remained (Fig. 23). Five spiders
molted to the adult stage with only the palpal coxae present.

The amputation experiments performed on pre-penultimate
male L^ variolus palps are summarized in Table 1.

Fig. 21. Results of amputation of the pre-penultimate
palp at the femur-patella joint.

X /:-s^

X / • ■ •

A V

N /V^.

^ / .--' %

..^

< ^ ^

X • ■ s

■^<

jnoji-

Fig. 22. Results of amputation of the pre-penultimate
palp at the mid-feraur and t rochanter-f emur joint.

.^y<f

y^->\

Fig. 23. Results of amputation of the pre-penultimate
palp at the coxa-trochanter joint.

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Amputation of penultimate palps

As in the previous series of experiments, it was desir-
able to discover the regenerative capacity of the penultimate
palps. According to Bonnet's work on Dolomedes (1930) it
would not be possible for either pre-penultimate or penulti-
mate palps to produce normal adult structures after injury.

Amputation at the mid-point of the tarsus

In twelve penultimate male L_^ variolus the distal half
of the tarsus was removed from one palp an average of 17
days (range = 9-25 days) into the instar. Eight spiders died
shortly after amputation without molting. The remaining four
spiders molted to the adult instar in an average of twelve
days (range = 4-17 days) with no regeneration occurring.
Coxae of the injured palps were the only structures present
(Fig. 24).

Amputation at the tibia-tarsus joint

A palp of each of ten penultimate males was amputated
at the tibia-tarsus joint an average of five days (range = 2-
16 days) into the instar. All of the specimens died v/ithin
two days of amputation without molting (Fig. 25).

Damage to the palpal tarsus

The tarsus of one palp of five penultimate males was
damaged by puncture an average of twelve days (range = 1-25
days) into the instar. The only spider to survive molted
to the adult instar 19 days after injury without any regener-
ation (Fig. 26).

'"•^^"K

/(■■

v/x

/:V

' -^l ~" 1

•■'"<"-\.

-'~J. - •>

rxkki

■ >- :VV.v/

Y^^

<.-:.Z.ili;^x;-/

/ ^

\--\

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nidi.

fi/7o

337o

Fig. 24. Results of amputation of the penultimate palp at
the mid-tarsus.

DEATH -no molt

Fig. 25. Results of amputation of the penultimate palp at
the tibia-tarsus joint.

molt

--^ji-

D£ATH-no moit
80%

20"/c

Fig. 26. Results of damage (puncture) to the tarsus of
the penultimate palp.

Amputation at the patella-tiTjia joint

The tibia and tarsus from each of ten penultimate males
was amputated an average of two days (range = 1-2 days) into
instar. Two spiders died without molting. The remaining
eight specimens molted to the adult instar an average of 41
(range = 30-61) post-amputation days with no regeneration
displayed by any spider. The injured palps appeared in the
adult stage with a coxa, trochanter, femur and patella.
The distal margin of the patella v/as healed over (Fig. 27),

Amputation at the coxa-trochanter joint

In twelve penultimate males a palp was amputated at the
coxa-trochanter joint; eleven of which survived to the adult
stage in an average of 15 days (range = 4-27) after amputation
No regeneration of the injured palps was observed (Fig. 28). .

The amputation experiments performed on the palps of
penultimate male L^ variolus are sumjnarized in Table 2,

Ligature of Pre-penultimate and Penultimate Palps
Ligation of pre-penultimate and penultimate palps was
perform.ed to discover if this type of injury would result in
the autotomy of the palps.

Ligature at mid-point of pre-penultimate palp

In ten pre-penultimate males the mid-point of the palpal
fem.ur was ligated an average of nine days (range = 1-32) into
the instar. Two spiders died one day after ligation. Four of
the remaining spiders apparently autotomized their injured
palp one day after ligation.

_m5ii.

Fig. 27, Results of amputation of the penultimate palp
at the patella-tibia joint.

molt

Fig. 28. Results of amputation of the penultimate palp
at the coxa-trochanter joint.

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Ligature at the tibia-tarsus joint of penultimate palp

In five penultimate males, an average of 14 days
(range = 1-20) into the instar, the tibia-tarsus joint of a
palp was ligated. One spider died a day after ligation. One
of the surviving four specimens exhibited the apparent autot-
omy of the palp two days after the application of the liga-
ture.

Ligature at the mid-femur of the penultimate palp

In eight penultimate males the mid-femur of the palp was
ligated an average of 48 days (range = 12-129) into the
instar. Six specimens died within two days of ligation. No
autotomy was observed in the remaining two spiders.

The ligation experiments performed on the palps of pre-
penultimate and penultim.ate male L_^ variolus are summarized
in Table 3.

Regeneration and Autotomy in the Legs of L. variolus

Regeneration and autotomy in the legs of L_^ variolus were
studied using two types of injury, amputation and ligation.
Amputation left an open wound requiring healing whereas
ligation did not. The first logon the left side of fourth
and fifth instar female L. variolus was amputated at differ-
ent points in an effort to determine the most proximal point
from which amputation resulted in regeneration of the limb.

Amputation at the mid-point of the telotarsus

In six spiders the distal half of the telotarsus was
removed two days into the instar. With the first post-ampu-

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tation molt the injured telotarsi had regenerated to approx-
imately 50% the size of the normal corresponding structure
(Fig. 29). The tarsal claws were present and normal in
appearance. With the second post-injury molt all injured
legs were normal in size and appearance.

Amputation at the mid-point of the basitarsus

In ten immature female L. variolus a leg was amputated
at the mid-point of the basitarsus an average of three days
(range = 1-11) into the instar. Following the first post-
amputation molt all of the spiders exhibited regeneration
where the basitarsus was 33-100%, and the telotarsus 25-33%
normal by comparison to corresponding structures. By the
second molt four had regained normal appearing legs. After
the third post-injury molt all specimens displayed normal
legs (Fig. 30) .

Amputation at the mid-point of the tibia and at the patella-
tibia joint

In 14 specimens a leg was amputated at the raid-point of
the tibia and ten other spiders had a leg amputated at the
patella-tibia joint. Amputations were made when the spiders
were an average of nine days (range = 1-45 days) into the in-
star. All exhibited regeneration at the first post -amputation
molt an average of 17 (range = 7-45) days later with the tibia
33-50%, basitarsus 20-50% and telotarsus 20-50% normal by
comparison with normal corresponding structures (Fig. 31) .
Tv/o spiders had regenerated a normal leg by their second post-
injury molt and twelve had normal legs by the third molt
following amputation.

Fig. 29. Results of amputation of the leg at the mid-telo-
tarsus .

Fig. 30. Results of amputation of the leg at the mid-
basitarsus .

Fig. 31. Results of amputation of the leg at the mid-
tibia and at the patella-tibia joint.

Amputation at the femur-patella joint

In each of six spiders a leg was cut at the femur-patella
joint one day into the instar. One specimen died two days
after amputation without molting. Four of the remaining
spiders molted in an average 25 (range = 18-39) days later and
regenerated the patella 50-100%, tibia 50-75%, basitarsus
33-50% and telotarsus 20-33% normal by comparison (Fig. 32),
No spider had regenerated a normal leg by the second and only
two had regenerated normal legs by the third post -amputation
molt. One spider had only the coxa of the injured leg
evident after two post-injury molts.

Amputation at the mid-point of the femur

In 20 spiders a leg was amputated at the mid-point of
the femur an average of 18 (range = 1-35) days into the instar.
One spider died without molting. The first post-amputation
molt came an average of 38 (range = 16-58) days later with
70% of the survivors regenerating the femur 33-75%, patella
33-50%, tibia 20-50%, basitarsus 20-33% and telotarsus 20-25%
by comparison to normal structures (Fig. 33). None of the
above had regenerated a normal leg by the second and only one
spider had regenerated a normal leg after the third post-
amputation molt. The remaining 30% of the survivors display-
ed wound healing at the site of amputation with no subsequent
regeneration.

Fig. 32. Results of amputation of the leg at the femur-
patella joint .

Fig. 33. Results of amputation of the leg at the mid-feraxir.

Fig. 34. Results of amputation of the leg at the trochanter-
f emur joint .

Amputation at the trochanter- femur joint

In ten spiders a leg was amputated at the trochanter-
feraur joint an average of 27 (range - 5-48) days into the
instar. No specimen exhibited regeneration at any post-
amputation molts. In every case the trochanter had healed
over (Fig. 34).

Amputation at the coxa-trochanter joint

A leg from each of 15 spiders was removed at the coxa-
trochanter joint by pulling on the leg with forceps. Ampu-
tation occurred an average of 12 (range = 1-39) days into the
instar. No regeneration occurred at any subsequent molts
leaving only the coxae of injured legs (Fig. 35).

Amputation at the proximal margin of the coxa

In ten spiders one of the second pair of legs was removed
by cutting around the proximal margin of the coxa. Only two
spiders survived the injury and exhibited no regeneration of
any leg structures. The wound healed over completely in the
two survivors (Fig. 36).

The amputation experiments performed on the legs of L.
variolus are summarized in Table 4.

Localized Injury to the Femur
This experiment was performed to discover if L_^ variolus
had the ability to regenerate a leg from a local injury to
the femur. Bohn (1965) inflicted local injury to the tibia
of a cockroach (L_^ raaderae) by removing a V-shaped section of

i;?

Fig. 35. Results of amputation of the leg at the coxa-
trochanter joint.

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\ n:' I|v.; '^v^?:^?^^^!! '/'Is

Fig. 36. Results of amputation of the leg at the proximal
margin of the coxa.

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tissue. This resulted in a lateral regenerate, in the form
of a leg, at the site of injury.

From each of 15 spiders a section of tissue was cut
from the femur. One spider died without molting. Six
specimens autotomized the injured limb at the coxa- trochanter
joint in an average of four (range = 1-7) days after injury
(Fig. 37). Autotomized limbs did not regenerate with only
the coxa remaining following subsequent molts. These
results are comparable to those obtained by mechanical removal
of the leg at the autotomy plane.

The other eight spiders exhibited healing of the wound
following injury and a concave scar following the post-injurj?-
molt (Fig. 37). The scar area was characterized by a lack
of setae. No lateral regenerates resulted from this type of
injury to L_^ variolus.

Ligature of the Legs
Ligature was used to inflict injury to the leg without
resulting in an open wound. Such an injury, however, is
sustained for longer periods of time since the ligature is
in place until discarded by some mechanical means or at the
post-ligature ecdysis.

Ligature at the m-id-point of the basitarsus

Ten spiders were ligatured at the mid-point of the
basitarsus an average of 49 (range = 36-67) days into the
instar. One day after ligature four spiders had lost,

AUTOTOMY 40^/o

Fig. 37. Results of localized injury to the femur of the
leg.

apparently by a mechanical means, the portion of the injured
leg distal to the ligature. The effect therefore was of
amputation at that point. No autotomy was observed. All of
the spiders regenerated at the next molt, an average of 20
(range = 17-40) days later, with the basitarsus 75-1007o and
telotarsus 50% normal (Fig. 38). Fifty percent of the
spiders had regenerated a normal leg by the second molt.

Ligature at the mid-point of the tibia

A leg from each of 20 spiders was ligatured at the mid-
point of the tibia an average of 19 (range = 16-22) days
into the instar. Fourteen specimens autotomized the injured
limb at the coxa-trochanter joint in an average seven (range =
1-14) days after ligature. No post-autotomy regeneration
was exhibited, leaving only the coxa of the ligatured/autot-
omized limb in evidence.

The six spiders that did not autotomize the ligatured
limb did, however, remove the leg tissue distal to the
ligature as described above in the preceding experiment in
2 to 23 days. These spiders did regenerate the tibia 50-67%,
basitarsus and telotarsus 25-33% at the first post-ligature
ecdysis (Fig. 39).

Ligature at the patella

Six spiders were ligatured at the patella of one leg.
Five spiders autotomized the injured leg in an average of
seven (range = 1-12) days after injury. The remaining specimen
molted 20 days after ligation with the patella 50%, tibia 50%,
basitarsus 33% and telotarsus 20% normal by comparison (Fig. 40)

Fig. 38. Results of ligation of the leg at the mid-
basitarsus.

Fig. 39. Results of ligation of the leg at the mid-tibia,

Ligature at the mid-point of the femur

One leg of each of ten spiders was ligatured at the mid-
point of the femur an average of 38 (range = 1-59) days into
the instar. All ten specimens autotomized the ligatured
limb at the coxa-trochanter joint within one day of injury.
No regeneration of the limbs was observed. Only the coxa
of ligatured/autotoraized legs remained after subsequent
molts (Fig. 41) .

External Force Applied at Autotomy Plane
This experiment was performed to determine if an injury
applied to the plane of weakness powerful enough to produce
bleeding but mild enough not to cause severence of the limb,
would result in autotomy. It was necessary to perform this
experiment since the possibility existed that this type of
injury may occur as a result of the manipulation of spiders
for any of the previously described experiments.

In the 20 spiders tested in this manner at an average
of 18 (range = 5-55) days into the instar no autotomy result-
ed and all specimens molted to the next instar with no
morphological anomalies observed.

The ligature and external force experiments performed
on the legs of L_^ variolus are summarized in Table 5.

Summary of Results
Latrodectus variolus has the capacity to regenerate a
normal adult male palp only if the injury occurs distal to
the mid-point of the tarsus during or before the pre-penulti-

ADTOTO?'JY 83=/o

Fig. 40. Results of ligation of the leg at the patella.

AUTOTO:v^Y

'Fig. 41. Results of ligation of the leg at the mid-femur,

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mate instar, thus allowing at least two more molts before
maturation. Injury to the palp sustained proximal to the
mid-point of the tarsus during the pre-penultimate instar
did not result in normal regenerates. Ligation at the mid-
femur of the pre-penultimate palp resulted in apparent
autotomy 40% of the time and in death 20% of the time.

Injury to the penultimate palps by ligation or ampu-
tation did not result in regeneration. Amputation of the
tibia and/or tarsus of the penultimate palp frequently
resulted in the death of the spider. Ligation at the tibia-
tarsus joint of the palp resulted in apparent autotomy in
20% of the cases and in death in 20% of the cases.

Amputation of the legs of immature L_. variolus resulted in
either regeneration or healing of the wound with no subse-
quent regeneration. Regeneration resulted when am.putation
occurred at or distal to the mid-point of the femur. Amputa-
tion at points proximal to the femoral mid-point to the
proximal margin of the coxa resulted in the healing of the
wound. Penultimate males (15) had legs amputated at various
points and all exhibited regeneration or healing as described
for immature females. Amputation of a leg of a penultimate
male in no way interf erred with palpal development.

Autotomy of the leg was first observed resulting from
localized injury to the femur. Removal of a section of
tissue from the femur resulted in either healing of the wound
at the first post-injury molt or autotomy of the entire limb
at the coxa-trochanter joint with no subsequent regeneration.

Ligation at various points of the leg of L^ variolus
resulted in either regeneration or autotomy. The more
proximal the ligation the greater the frequency and earlier
was the onset of autotomy. Ligature of the basitarsus never
resulted in autotomy. Autotomy of the legs always occurred
at the coxa-trochanter joint.

DISCUSSION

Regeneration

This investigation has established the regenerative
capacities for the legs and developing palpal organ of L.
variolas. The occurrence of autotomy in L^ variolus was
documented and compared to regeneration and healing as
alternative responses to injury by amputation and ligature.
This research has demonstrated that like other arthropods,
L. variolus has the capacity to regenerate limbs injured by
amputation or ligation. However, the black widow spider,
L. variolus does not have the ability to regenerate a leg or
palp following autotomy. This completely contradicts state-
ments made by Goss (1969) and Needhara (1965). Goss stated
that the capacity for regeneration in arthropods was greatest
at the autotomic breakage plane. Needham remarked that the
specific rate of regeneration is greatest when amputation
occurs at the autotomy plane. The evidence strongly suggests
the capacity for regeneration is non-existent at the autotomic
breakage plane of L_^ variolus . In fact, the capacity for
regeneration in the leg does not become apparent until some
distance distal to the autotomy plane, at about the mid-
point of the femur.

The palps of pre-penult imate male L_^ variolus can regen-
erate to normal penultimate and subsequent adult palps if

the injury involves the loss of less than the distal half of
the tarsus. VJhen loss of more than the distal half of the
pre-penultimate tarsus is sustained, there is tissue regen-
eration but insufficient to produce normal penultimate and
adult palpal structures.

These results help to confirm the suspicions of
Chrysanthus (1955) and Kaston (1963, 1968) that some malforma-
tions of penultimate and adult male spider palps could be
attributed to imperfect regeneration following injury.
Kaston (1968) reported a deformity in a penultimate palp of
L. hesperus viheve one palpal tarsus was only half the size of
the corresponding normal palp. This was observed in experi-
mentation with L^ variolus when the tibia and tarsus of the
pre-penultimate male palps were amputated.

In the current research amputations of penultimate palps
never resulted in regeneration. Death occurred soon after
the amputation of the distal half of the tarsus in 60% of the
cases and in 100% of cases where the entire tarsus had been
removed. Death did not occur when amputations were made at
or proximal to the patella-tibia joint. In those cases the
v/ound healed and the subsequent molt to the adult instar result-
ed in no regeneration.

Amputation and ligation of penultimate palps resulted
only in the healing of the remaining portions of the palp or
the death of the spider. Once the palp has reached the level
of development seen in the penult im.ate palp damage is either
fatal or repaired by healing since the evidence suggests that

the tissue of the penultimate palp has lost the capacity to
regenerate. The pre-penult imate palp retains the ability to
regenerate the palpal organ as the histological examination
of regenerate penultimate palps indicated. The regenerate
cells in such a palp still form a developing palpal organ,
although smaller than its normal counterpart, but has apparent-
ly lost the ability to react to the developmental hormones
at the final molt. Palps injured during the pre-penult imate
stage that regenerated a small penultimate palp never develop-
ed beyond that point even when the spiders involved molted

to the adult stage.

A comparison of the regenerative capacities of pre-
penultimate and penultim.ate palps is presented in Figure 42.

Ligation of the femur of pre-penult imate palps resulted
in death in 20% and apparent autotomy in 40% of the cases.
Ligation at the tibia-tarsus joint and mid-femur of penulti-
mate palps resulted in death 20% and 75% and apparent autotomy
in 20% and 0% of the cases respectively. Due to the size and
delicacy of the palps and the extreme difficulty in performing
the ligation procedures I consider the data on ligation of the
palps to be less than totally reliable. Further sophistica-
tion of the techniques for palpal ligation may yield more
satisfactory results.

There seems a strong possibility that deaths resulting
from amputation through the large cross-sectional areas of
the penultimate palp may be related to the size of the wound.
Cuts made through the bulbous portion leave a much greater

PRE-PENULT!MflT£

pHealin

PENULTIMATE

Fig. 42. Comparison of the regenerative capacities of the
pre-penultimate and penultimate palps of the male
L. variolus.

wound than do cross-sectional cuts through the more proximal
segments of the palp. Harvey and V^illiams (1961) reported
that the "injury factor" in diapausing cecropia seemed to be
released until the wound was sealed by blood cells. Amputa-
tion through the largest cross-sectional area of the pre-
penultimate palp, at the tibia-tarsus joint, is sealed by
the healing process (Fig. 43) and the spiders survive to molt
again. However, injury at the same point in the penultimate
palp results in the death of the animal. The only perceivable
difference is the size of the wound. Since the palps did
not exhibit autotomy in response to amputation it may be
possible that a larger amount of wound factor released from
the larger wound, a wound that was not sealed by blood cells,
may have resulted in the death of the spiders.

Amputation indicated that the regenerative capacity of
the legs is greatest in the more distal segments. However,
amputations as high on the leg as the patella-tibia joint
resulted in some regeneration 100% of the tim-. No leg
injured by amputation or ligature regenerated completely
at the first post-injury molt. It is from the mid-point of
the femur (30% of the time) to the proximal margin of the
coxa that healing of the wound occurs with no subsequent
regeneration.

The regeneration observed in the legs and palps of L.
variolus complies with the developmental gradient model for
regeneration set forth by Bryant (Fig. 1). Proximal struc-
tures left after amputation or ligature regenerate those
portions lower (more distal) on the developmental gradient.

Autotomy

Autotomy was first observed in the experiment where
local injury of the leg resulted from removal of a section
of tissue (Fig. 37) from the femur. Forty percent of the
spiders thus injured exhibited autotomy of the entire limb
at the coxa-trochanter joint not followed by any regeneration
of the lost limb. A possible agent involved in the physio-
logical "choice" between healing and autotomy may be the size
of the wound and the corresponding release of v/ound factor.
Autotomized legs in this experiment showed no signs of heal-
ing (Fig. 44) at the time the leg was released from the body,
possibly indicating a wound too large to be sealed. Wound
factor would then be released until the threshold for autot-
omy was reached, after which the leg would be severed from
the body by the mechanism described by Parry (1957).

Autotomy of the legs was a frequent result of ligation.
A comparison of the autotomy, healing and regeneration of
legs injured by amputation or ligature is presented in Figure
45. Ligature resulted in the autotomy of the entire leg 70%
of the time when applied to the mid-point of the tibia,.
Amputation at the same point never resulted in autotomy.
Autotomic reactions increased in frequency as more proximal
segments of the leg were ligatured.

Ligation distal to the mid-point of the tibia (at the
mid-point of the basitarsus) did not result in autotomy. The
lack of autotomy following injury to the dactyl of crustacea
has been attributed to the fact that the leg nerve of those
animals does not extend into that segment (Hodge, 1956;

Healed
wound

Fig. 43. Healing of the wound produced by amputation of
the pre-penultimate palp at the tibia-tarsus joint.

r>r-> ■■

Open wound

Fig. 44. The open wound of an autotomized leg after
localized injury to the femur of the leg.

Ligation

Amputation

Autotomy

-Regeneration ^

-:^jr,^^s^MM^ss^m^^^^

^"^.-^v-

Regeneration

Fig. 45. A comparison of the autotomy, healing and
regeneration of the legs injured by amputation
and ligation.

Fig. 46. Histology of the telotarsus of the leg of
L. variolus showing the leg nerve present .

■^'^iZ.T^iXa

Needhara, 1947; and Wood, et al . , 1932). No autotomy occurs
when injury, either by amputation or ligation, is applied to
the distal segments of the leg of L^ variolus even though
the leg nerve is present to the tip of the telotarsus (Fig. 46)
This fact argues against nervous reflex as a cause )of autotomy,
at least in the distal segments of the leg, in L_^ variolus.

It seems logical at this point to assume that ligation
resulted in autotomy whereas amputation did not because of
the greater duration of injury sustained with ligation. A
cross-sectional cut of a leg leaves a wound capable of healing
before the hypothetical wound factor threshold for autotomj?^
is reached, thus no autotomy due to amputation was observed.
Ligation is applied for longer periods of time, either until
its mechanical removal or the first post-ligature molt. The
greater duration of injury may result in wound factor pro-
duction long enough to reach the autotomy threshold. This
theory presupposes that wound factor is released in the
absence of an open wound.

The argument that a wound factor contributes to the
initiation of autotomy becomes stronger when the experiment
taxing the autotomy plane is considered. Following the: split
of the articulating membrane at the coxa-trochanter joint
caused by pulling, the release of hemolymph is proof the
autotomy plane has been directly damaged. The pressure was
not great enough to cause the direct loss of the leg.
According to Harvey and Williams (1961) injury factor would
have been released from such an injury but because the wound

was quickly sealed when the split edges of the membrane
came back into contact with each other the dose of wound
factor would have been relatively small. Although the
plane of weakness was injured directly and wound factor
supposedly released, autotomy did not occur, presumably
because the dose of wound factor did not reach the threshold
and no reflex in response to the pressure applied caused

the loss of the leg.

Autotomy has been demonstrated following injury to
points on the leg distal to the plane of weakness where
the injury was sustained for a longer period of time, either
by duration of application (ligature) or by the failure of
the wound to heal in some reasonable amount of time (local
femoral injury). It seems possible that the duration and/or
size of the injury, both related to the dose of wound factor
released, contributes to the initiation of autotomy.

Autotomy is a costly alternative to regeneration in
L. variolus since once a limb is autotomized regeneration of
that limb is impossible. The adaptive advantage to a plane
of weakness in a spider appendage is great. It is more
advantageous for an animal to sacrifice a limb in order to
escape than to be killed or fatally wounded in an encounter
with a predator. Loss of a single leg to a web-dwelling
spider may be of little consequence although no investigation
of that phenomenon has been performed. In the black widow
spider, L^ variolus, the ability to escape or discard a badly
injured limb outweighs the advantage of regenerating those
limbs .

The difference in the regenerative capacities of the
legs and palpal organ may be related to the degrees of com-
plexity of the two morphologically homologous appendages.
The loss of one leg may be of little consequence since
there are seven remaining. The palps of the male are at a
relative premium since there are but two. Although only
one palp is required for successful copulation, two palps
would enhance the chances that a male spider's genes would
be transmitted to the next generation.

A physiological response gradient has been established
for the legs and developing palpal organ of L^ variolus dis-
tinguishing between regeneration, healing, autotomy and death
as responses to injury by amputation and ligation (Figs. 42
and 45) .

In answering the questions posed earlier concerning the
regenerative capacities of the legs and palps of L_^ variolus
a major question has been reopened. What is the "wound
factor" and how is it related to regeneration, healing,
autotomy and death, the alternative responses to injury? Is
wound factor a universal agent found in all organisms in the
same form or is it unique to each species?

The answers to those and other questions await discovery
and discoverers.

APPENDIX 1

Fixation, Dehydration and Embedding Protocol
From fixation in alcoholic Bouin's fixative:

70% EtOH
70% EtOH
30% EtOH
50% EtOH
70% EtOH
80% EtOH
90% EtOH
95% EtOH
100% EtOH
1:1, 100% EtOK: Acetone
Acetone

1:1, Acetone:Terpineol
Terpineol

Benzene
Benzene

1:1, Benzene:Paraplast

@ 55-60°

Paraplast @ 55-60°
Embed in Paraplast

5-15 min.
5-15 min.
5-10 min.
5-10 min.
5-10 min.
5-10 min.
5-10 min.
5-10 min.
5-10 min.
5-15 min.
5-10 min.
10-15 min.

4 hours to overnight

(can be stored in terpineol)

5 min.
5 min.

15-30 min.
15-45 min.

Paraffin blocks were trimmed and sectioned in rotary
microtome.

Sections were mounted on standard glass microscope
slides.

APPENDIX 2

Mallory's Triple Stain Technique

Xylene 2-5 min.

100% EtOH 2-5 min.

95% EtOH 2-5 min.

80% EtOH 2-5 min.

70% EtOH ■ 2-5 rain.

50% EtOH 2-5 min.

30% EtOH 2-5 min.

Water 2-5 min.

Stain in 1% acid fuchsin for 2-5 min. (time not
critical)

Rinse in water for 1 min.

Transfer to 1% phosphotungstic acid for 2 min.
(time not critical)

Dip twice in water

Transfer to second staining solution (100 ml water,
0.5g methylene blue, 2g orange G and 2g oxalic
acid) for 5 min. (no more than 8 min.)

Wash in water - two 1 min. washes

Transfer to 100% alcohol for li min. - time is critical

Place in xylene - can stay in xylene until ready to mount

Pro-Tex or Perraount mounting medium are both good
mount ants.

LITERATURE CITED

Agar, W. E. 1930, A statistical study of regeneration in ^> ■
two species of Crustacea. J. Expt . Biol. 7:349-369.

Baerg, W. J. 1923. The black widow: Its life history and
effects of its poison. Sci. Monthly 17:535-547.

Bhatnagar, R. D. S. and J. G. Rempel. 1962. The structure,
function and post-embryonic development of the male and
female copulatory organs of the black widow spider
Latrodectus curacaviensis (Muller). Can. J. Zool. 40:465-
510.

Bliss, D. E. 1960. Autotomy and regeneration. Pages 561-589
in T. H. Waterman, ed. The physiology of Crustacea.
Academic Press, N. Y.

Bodenstein, D. 1933. Beintransplantationen an lepidopter-
enraupen II. Zur analyse der regeneration der brust-
beine von Vanessa urticae - Raupen . Wilhelra Roux
Arch. EntwMech. Org. 165:303-341.

Bodenstein, D. 1955. Contributions to the problem of regen-
eration in insects. J. Expt. Zool. 129:209-224.

Bohn, H. 1955. Analyse der regenerationsf ahigkeit der

insektenextremitat durch amputations - und transplanta-
tionsversuche an laven der Afrikanischen schabe Leuco-
phaea maderae Fabr. (Blattaria) . II. Achsendetermin-
ation. \7iihelm Roux Arch. EntwMech. Org. 156:449-503.

Bohn, H. 1972. The origin of the epidermis in the super-
numerary regenerates of triple legs in cockroaches
(Blattaria). J. Embryol. exp. Morph . 32(l):81-98.

Bohn, H. 1974a. Extent and properties of the regeneration
field in the larval legs of cockroaches (Leucophaea
maderae). I. Extirpation experiments. J. Embryol. exp.
Morph. 31(3): 557-572.

Bohn, H. 1974b. Extent and properties of the regeneration
field in the larval legs of cockroaches (Leucophaea
maderae) . II. Confirmation by transplantation experi-
ments. J. Embryol. exp. Morph. 32(1): 69-79.

Bohn, K. 1974c. Extent and properties of the regeneration
field in the larval legs of cockroaches (Leucophaea
maderae) . III. Origin of the tissues and determination
of syminetry oroperties in the regenerates. J. Embryol .
exp. Morph. 32(1): 81-98.

Bonnet, P. 1930. La mue, 1 ' autotomie, et le regeneration
Chez les Araignees. Bull. soc. hist, nat . Toulouse
59(2):613-939.

Brousse-Gaury, P. 1958. Contribution a 1' etude de 1' autot-
omie Chez Acheta domestica L. Bull. biol. France et
Belg. 92:55-85.

Bryant, P. J. 1971. Regeneration and duplication following
operations in situ on imaginal discs of Drosphila
melanogaster. Devel. Biol. 26:606-615.

Bryant, P. J. 1975. Pattern formation in the imaginal wing
disc of Drosophila melanogaster: Fate map, regeneration
and duplication. J. Expt . Zool. 193:49-78.

Bulliere, D. 1967. Etude de la regeneration chez un insecte
Blattopteroide, Blabera craniifer Burm. (Dictyoptere) .
I. Influence du niveau de la section sur la regenera-
tion de la patte metathoracique. Bull. Soc. Zool. Fr.
92:523-536.

Bulliere, D. 1971. Utilization of intercalary regeneration
for the study of cellular determination in the course
of morphogenesis of Blabera craniifer. Devel. Biol.
25:672-710.

Burt, C. E. 1935. A review of the biology and distribution
of the hourglass spider. J. Kan. Entomol. Soc. 8:117-
130.

Chamberlin, R. V. and Y/ . I vie. 1935. The black widow

spider and its variations in the United States. Bull.
Univ. Utah 25(8):Biol. Ser. 3(1):1-18.

Chrysanthus, Fr. 1955. On defectively regenerated palps
in male spiders. Natuurhist . Mnbld. 44:56-59.

Deevey, G. B. 1949. The developmental history of Latrodectus
mactans at different rates of feeding. Amer. Midi. Nat.
42:189-219.

Emmel, V. E. 1910. Differentiation of tissues in the re-
generating crustacean limb. Am. J. Anat . 10:109-156.

French, V., P. J. Bryant and S. V. Bryant. 1976. Pattern
regulation in epimorphic fields. Sci. 193:969-981.

Friedrich, P. 1906. Regeneration der beine vmd autotoraie
bei spinnen. Arch. f. Entwm. Bd. 20.

Goss, R. J. 1965. The functional demand theory of growth
regulation. Pages 445-451 in V. Kiortsis and H. A. L.
Trampusch, eds . Regeneration in animals and related
problems. North-Holland Publ. Co., Amsterdam.

Goss, R. J. 1969. Principles of regeneration. Academic
Press, N. Y. 287 pp.

Hagstrum, D. W. 1968. Molting behavior of the black widow
spider Latrodectus mactans. Ann. Entomol. Soc. Amer.
61:591-593.

Harvey, W. R. and C. M. Williams. 1961. The injury metabol-
ism of the cecropia silkmoth - I. Biological amplifica-
tion of the effects of localized injury.. J. Insect
Physiol. 7:81-99.

Hodge, M. H. 1956. Autotomy and regeneration in Gecarcinus
lateralis. Anat . Rec. 125:633.

Jellison, W. L. and C. B. Philip. 1935. The biology of the
black widow spider Latrodectus mactans . Sci. 81:71-72.

Kaston, B. J. 1937. The distribution of black widow spiders.
Sci. 85:74.

Kaston, B. J. 1954. Is the Black V/idow Spider invading
New England? Sci. 119:192-193.

Kaston, B. J. 1963. Deformities of external genitalia in
spiders. J. N. Y. Entomol. Soc. 21:30-39.

Kaston, B. J. 1958. Remarks on Black Widow Spiders, with an
account of some anomalies. Entomol. News. 79(2) : 113-124

Kaston, B. J. 1970. Comparative biology of American Black

Widow Spiders. Trans. San Diego Soc. Nat. Hist. 16(3):
33-82.

Lawson, P. B. 1933. Notes on the life history of the hour-
glass spider. Ann. Entomol. Soc. Amer. 26:568-574.

Levi, H. W. 1958. Number of species of black widow spider.
Sci. 127:1055.

Luscher, M. 1948. The regeneration of legs in Rhodnius
prolixus (Hemiptera). J. Expt . Biol. 25:334-343.

McCrone, J. D. 1968. Biochemical differentiation of the
sibling black widow spiders, Latrodectus mactans and
L^ variolus. Psyche 74:212-217.

Needham, A. E. 1945. Peripheral nerve and regeneration in
Crustacea. J. Expt. Biol. 21:144-146.

Needham, A. E. 1947. Local factors and regeneration in
Crustacea. J. Expt. Biol. 24:220-226.

Needham, A. E. 1949. Growth and regeneration in Asellus
aquaticus (L.) in relation to age, sex, and season.
- J. Expt. Zool. 112:49-78.

Needham, A. E. 1950. Determination of the form of regener-
ating limbs in Asellus aquaticus. Quart. J. Microscop.
Sci. 91:401-418.

Needham, A. E. 1953. The central nervous system and regen-
eration in Crustacea. J. Expt. Biol. 30:151-159.

Needham, A. E. 1965. Regeneration in arthopoda and its
endocrine control. Pages 283-323 j^ V. Kiortsis and
H.A.L. Trarapusch, eds. Regeneration in animals and
related problems. North-Holland Publ. Co., Amsterdam.

O'Farrell, A. F. and A. Stock. 1953. Regeneration and the
molting cycle in Blattella germanica L. I. Single
regeneration initiated during the first instar. Aust .
J. Biol. Sci. 6:485-500.

O'Farrell, A. F. and A. Stock. 1954. Regeneration and the
molting cycle in Blattella germanica L. III. Succes-
sive regeneration of both metathoracic legs. Aust.
J. Biol. Sci. 7:525-536.

O'Farrell, A. F., A. Stock and J. Morgan. 1956. Regenera-
tion and the molting cycle in Blattella germanica L.
IV. Single and repeated regeneration and metamorphosis,
Aust. J. Biol. Sci. 9:406-422.

Parry, D. A. 1957. Spider leg muscles and the autotomy
mechanism. Quart. J. Microscop. Sci. 98:331-340.

Paul, J. H. 1914. Regeneration of the legs of decapod
Crustacea from the preformed breaking plane. Proc.
Roy. Soc. Edinburgh 35:78-91.

Paul, J. H. 1915. A comparative study of the reflexes of

'autotoray in decapod Crustacea. Proc. Roy. Soc. Edinburgh
35:232-262.

Penzlin, H. 1963. Uber die regeneration bei schaben

(siattaria). I. Das regenerations-vermogen und die
genese des regenerats. Wilhelrn Roux Arch. EntwMech.
Org. 154:434-465.

Rempel, J. G. 1957. The embryology of the black widow spider,
Latrodectus mactans (Fabr.). Can. J. Zool. 35:35-74.

Ross, K. and R. L. Smith. 1979. Aspects of the courtship

'behavior of the black widow spider, Latrodectus hesperus
(Araneae: Theridiidae) , with evidence for the existence
of a contact sex pheromone. J. Arachnol. 7:69-77.

Savory, T. 1977. Arachnida. Academic Press, N. Y. 340 pp.

Schultz, E. 1898. Uber regeneration von spinnenfussen,

Trav. Soc. Nat. Petersbourg, XXIX L. 1,(2). Comptes
Rendus Seances, 94-95.

Snodgrass, R. E. 1965. A textbook of arthropod anatomy.
Hafner Publ. Co., N. Y. 363 pp.

Urvoy, J. 1963. Etude anatomo-functionnelle de la patte

et de I'antenne de la blatte Blabera craniifer Burmeister.
Ann. Sci. nat. Zool. Ser. XII 5:287-413.

Vachon, M. 1941. Chthonius tetrachelatus et ses formes
immatures. Bull. Mus. Hist. Nat., Paris 13:442-449.

Wagner, W. 1887. Le regeneration des organes perdus chez
les araignees. Sci. Imp. Nat. de Moscou.

Wilson, E. B. 1903. Notes on the renewal of asymmetry in
the regeneration of chelae in Alpheus heterochelis .
Biol. Bull. 4:197-210.

Wolpert, L. 1974. The development of pattern and form in

animals. Oxford Biology Readers #51, Oxford Univ. Press.

Wood, F. D. 1926. Autotomy in arachnida. J. Morph.
'42(1):143-195.

Wood, F. D. and H. E. Wood. 1932. Autotomy in decapod
'crustacea. J. Expt. Zool, 62:1-55.

Woodruff, L. C. 1937. Autospasy and regeneration in the

roach Blattella germanica (L.). J. Kan. Entomol. Soc.
10(l):l-9.

SUPPLEMENTARY BIBLIOGRAPHY

Barbosa, P. 1974. Manual of basic techniques in insect
histology. Autiimn Press, Amgerst, Mass. 244 pp.

Bodenstein, D. 1959. The role of hormones in the regenera-
tion of insect organs. Scientia 94:19-23.

Bryant, P. J. 1979. Pattern formation, growth control and
cell interactions in Drosophila imaginal discs. Pages
295-316. Determinants of spatial organization. S.
Subtelny and I. R. Konigsberg, ed. Academic Press,

N. Y.

Bryant, P. J., S. V. Bryant and V. French. 1977. Biological
regeneration and pattern formation. Sci. Amer. 237(1):
66-81.

Caveney, S. 1978. Intercellular communication in insect
development is horraonally controlled. Sci. 199:192-
195.

Dewes, E. 1973. Regeneration in transplanted halves of male
genital disks and its influence upon duration of develop-
ment in Ephestia kuhniella Z. Wilhelm Roux Archiv.
172:349-354.

Edwards, J. S. and J. Palka. 1971. Neural regeneration:

Delayed formation of central contacts by insect sensory
cells. Sci. 172:591-594.

Ehn, A. 1964. Aspects of determination in the spider embryo.
Zool. Bidr. Uppsala 37:3-20.

Etkin, W. and L. I. Gilbert. 1968. Metamorphosis. Appleton-
Century-Crofts, N. Y. 459 pp.

Furukawa, H. 1937. Reduplication experimentally produced
in the earwig, Anisolabis maritima (Dermaptera) . III.
Transplantation of forceps. Jap. J. Zool. 8:510-535.

Garcia-Bellido, A., P. A. Lawerance, and G. Morata. 1979.

Compartments in animal development. Sci. Amer. 241(1):
102-110.

Gordon R. and A. G. Jacobson. 1978. The shaping of tissues
in embryos. Sci. Amer. 238(6) : 106-113 .

Grant, P. 1978. Biology of developing systems. Holt,
Reinhart and Winston, N. Y. 720 pp.

Hadorn, E. 1968. Transdeterraination in cells. Sci. Amer.
2i9(5):110-120.

Krishnakumaran, A. 1961, A comparative study of the arachnid
cuticle. II. Chemical nature. Zeitz. Physiol.
44:478-486.

Krishnakiimaran, A. 1962. A comparative study of the cuticle
in arachnida. I. Structure and staining properties.
Zool. Jb. Anat. Bd. 80:49-64.

Krishnakumaran, A. 1972. Injury induced molting in Galleria
mellonella larvae. Biol. Bull. 142:281-292.

Kunkel, J. G. 1977. Cockroach molting. II. The nature

of regeneration-induced delay of m.olting hormone secre-
tion. Biol. Bull. 153:145-162.

Lawerence, P. A. and G. Morata. 1979. Pattern formation
and compartments in the tarsus of Drosophila. Pages
317-324 in Determinants of spatial organization.
S. Subtelny and I. R. Konigsberg, ed. , Academic Press,

N. Y.

Madhavan, K. and H. A. Schneiderman . 1969. Hormonal control
of iraaginal disc regeneration in Galleria mellonella
(Lepidoptera). Biol. Bull. 137(2) : 321-331.

Markert, C. L. and H. Ursprung. 1971. Developmental genetics,
Prentice-Hall, Inc., Englewood Cliffs, N. J. 214 pp.

Parry, D. A. 1960. Spider hydraulics. Endeavor 19:156-162.

Parry, D. A. and R. H. J. Brown. 1959. The hydraulic mechan-
ism of the spider leg. J. Expt . Biol. 36:423-433.

Parry, D. A. and R. H. J. Brown. 1959. The jumping mechan-
ism of salticid spiders. J. Expt. Biol. 36:654-664.

Pohley, H. J. 1965. Regeneration and the molting cycle in
Ephestia kuhniella. Pages 324-330 in V. Kiortsis and
H. A. L. Trampusch, eds. Regeneration in animals and
related problems. North-Holland Publ. Co., Amsterdam.

Schubiger, G. 1971. Regeneration, duplication and trans-
determination in fragments of the leg disc of Drosophila
melanogaster. Devel. Biol. 26:277-295.

Sewell, M. T. 1955. The histology and histochemistry of the
cuticle of a spider, Tegenaria domestica (L.). Ann.
Entomol. Soc. Amer. 48( 3) : 107-118 .

Shappirio, D. G. and W. R. Harvey. 1965. The injury metabol-
ism of the cecropia silkworm - II. Injury induced
alterations in oxidative enzyme systems and respiratory
metabolism of the punal wing epidermis. J. Insect
Physiol. 11:305-327.

Waddington, C. H. 1965. Principle of development and differ-
entiation. The Macmillan Co., N. Y. 115 pp.

VJilson, R. S. 1970. Some comments on the hydrostatic system
of spiders (Chelicerata, Araneae) . Z. Morph . Tiere
68:308-322.

Wolpert, L. 1978. Pattern formation in biological develop-
ment. Sci. Amer. 239( 4) : 154-164.

Woodruff, L. C. and L. Seamans. 1939. The rate of regener-
ation in the German roach. Ann. Entomol. Soc. Amer.
32:589-599.

BIOGRAPHICAL SKETCH

John Brookes Randall was born in Ft. Wayne, Indiana,
on April 7, 1949. He moved to Connecticut a year and a
half later, then to Maryland at age four. He attended high
school in Severna Park, Maryland, graduating in 1967. In
September of the same year he entered Maryville College,
Maryville, Tennessee, and received the Bachelor of Arts
degree in Biology from that institution in 1971.

For nearly two years after graduating from college he
worked as a physician's assistant in clinical research at
Johns Hopkins School of Medicine.

In September of 1973 he began graduate studies in
Entomology at the University of Florida under the direction
of Dr. Willard H. Whitcomb, during which time he served as
a graduate research and teaching assistant. He was awarded
a Visiting Graduate Student Fellowship to the Smithsonian
Institute in 1974 to study scientific illustration in that
museum's Department of Entomology. He received the Master
of Science degree from the University of Florida in June,
1976.

He continued graduate work for the doctoral degree under
the direction of Dr. Harvey L. Cromroy . He has recently
accepted a post-doctoral position at the State University

of New York at Buffalo where he will be investigating the
regeneration of insect nerve cells.

He holds membership in the Society of Sigma Xi , The
Entomological Society of America, The American Arachnological
Society, The Cambridge Entomological Club. The Florida Ento-
mological Society, The Guild of Natural Science Illustrators
and the International Society of Artists.

He has been married to his wife Carol for eight years ■
and they have a three-year-old daughter, Brooke Kathryn. ■

I certify that I have read this study and that in ray
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

(kA.Kj'-^X

, \>AN-

'"^VvMl

Harvey L. Cromroy , Chairman
Professor of Entomology

I ceriify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

^LdM^^

^I2Z_<^-^

ames Nation
Professor of Entomology

i^-7'<-^

I certify that I have read this study aJid that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

/^e^l i-Mj) &LfA Ufi^(-^
Herbert Ob er lander
Professor of Entomology

I cei-tify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

\l^.^J~4

mathan Reiskind
Associate Professor of Zoology

This dissertation was submitted to the Graduate Faculty of
the College of Agriculture and to the Graduate Council,
and v/as accepted as partial fulfillment of the requirements
for the degree of Doctor of Philosophy.

August 1979

DeanZ/College of Agr<£jCult

ure

Dean, Graduate School

UNIVERSITY OF FLORIDA

3 1262 08553 9731

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