Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. at © ms 2 oe TECHNICAL SERIES, No. 18. ese eA MENT OF AGRICULTURE, BURHAU OF HNTOMOLOGY. L. O. HOWARD, Entomologist and Chief of Bureau. THE ANATOMY OF THE HONEY BEE. BY R. KE. SNODGRASS, Agent and Expert. ISSUED May 28, 1910. i win | ye Hogs mn nd il I Bae | Ht es eh = b WASHINGTON: GOVERNMENT PRINTING OFFICE, 1910. BUREAU OF ENTOMOLOGY. L. O. Howarpb, Hntomologist and Chief of Bureau. CG. L. Maruatt, Assistant Entomologist and Acting Chief in Absence of Chief. R. 8S. CiiFrton, Haxecutive Assistant. W. EF. TAstet, Chief Clerk. FE. H. CHITTENDEN, in charge of truck crop and stored product insect investigations. A. D. HopxKINs, in charge of forest insect investigations. W. D. HUNTER, in charge of southern field crop insect investigations. F.. M. WEBSTER, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. EK. F. PHILLIPS, in charge of bee culture. D. M. RoceErs, in charge of preventing spread of moths, field work. RoutuaA P. CurRRIg, in charge of editorial work. MABEL COLCORD, librarian. INVESTIGATIONS IN BEE CULTURE. K. F. PHILLIPS, in charge. G. F. WHITE, J. A. NELSON, B. N. Gates, R. EH. SNoperass, A. H. McCray, agents and experts. IEXLLEN DASHIELL, preparator. JESSIE EK. Marks, clerk. T. B. Symons, collaborator for Maryland. H. A. SurFACE, collaborator for Pennsylwania. J. C. C. Price, collaborator for Virginia. 2 LETTER OF TRANSMITTAL. U. S. DreparTMENT or AGRICULTURE, Bureau or ENtTomMoLoey, Washington, D. C., October 19, 1909. Sir: I have the honor to transmit herewith a manuscript entitled “'The Anatomy of the Honey Bee,” by Mr. R. E. Snodgrass, agent and expert, of this Bureau. It embodies the results of detailed studies made by Mr. Snodgrass and should prove of value as bring- ing to the bee keeper reliable information concerning an insect of such great economic importance, and also as furnishing a sound basis In devising new and improved practical manipulations. I recommend its publication as Technical Series, No. 18, of the Bureau of Entomology. Respectfully, L. O. Howarp, Entomologist and Chief of Bureau. Hon. James Witson, } Secretary of Agriculture. IV. V. VI. CONTENTS. Reb ONd AE Cer AaRAA TM ee ee et ea Bo iti Sh te Gade Riqcner i enmernalsiTuciite OF. msects. -..-2... 2. ...o6-66 2c eect ee TT. ihemesdioncue pec.and jisappendares...2 2.2.24 22.6 2-25.-52-2 82.8 fe Pee iieiaILe Ol (He Meads ps ee Ss i BR See ek 2. Che antenns and their sense oreans:.....-:=.+---4+.-+=5----- ane tianatmos and qaew elands 8. ise et eek Bes 2 ae ECPI a aaeee Sn er I et eA Ro fg EL he thorasama li a ppendares. = 6) So... ke eed a ee Se He Ae imate eto at LW MOT oct oe So eo Sue She 2s 28 Zone wanosame Laer 2bhiemlaidom, .2.- 22 222 tl. J. 5 2 eas Sk £5 LUE VEES Ret es i Se een Ae = oe es eee te ane ee ee ene apvomen wax clands and stings... . . 4.260. .2 ens te ie aumenimry canal ands Glands: 2.2.8 . 5.285. oe 2 ks se Sa: < 1. The general physiology of digestion, assimilation, and excretion. peepee ciara INI es es nie a) ee eee as Bee oe eC Ss ae Ome amy ented Om 2 oe TS ed ke a a ds SS ee IRM IANO RN EPOME Fh Pie Se Ses eels Js See sien ee oe LE PenpME MIA EW RECT. Cort A el pie ied ee and fhe-Conocyies..— =. 2.2 62.0 ee ee ee Se peu mirrors system .and-the eyes ~~... ..,.5.25---2-4--0 e024 2- a2 -- eee EMU MVe Syatem. 2). Se ie eee Se eee ee bec eek deeeipenia lev otrans 2) 2 he os Sn Bed Saye eee) Wek Wine ees Peet CME AaECIOROUNES ho So 6 hte Sh a ek Cee oe oe OR ae Explanation of the symbols and letters used on the illustrations. .....-. eer EEO ei a ie ah URL. ha rad: Le 2 eur an er yg a ee sy Rh Eds by he Eee ILLUSTRATIONS. : Page Fic. 1. Median longitudinal section of body of qworker._ =) 32-22 8 2. Diagram of generalized insect embryo.................-.--- * pena a +2 3. Example of generalized insect mouth parts) 2222 ee 17 4. Diagram of generalized ‘thoracic sesment.::2 52-2222 22 - eee 19 5. Typical insect leg... 2 2.2 eee ee eee f 21 6. Diagram of generalized insect wing and its articulation..............- 22 7. Diagram of terminal abdominal segments of a female insect and early stage in development of gonapophyses:..... 2... 1225. 25 8. Example of a swordlike ovipositor 2222-2.) 62 =) eee 25 9. Head of worker: bee. 22.2 2 a ee ee 21 10. Heads of worker, queen, and drone.) 222222) ee 29 11. Median longitudinal sections of heads of worker and drone...........- 30 12. Antennal hairs and sense oreans:.<-= 2-2. 24...) 36 13.. Mandibles of worker and drone. 3227.22.22). =) 4a ee 40 14, Internal mandibular gland of worker... 922 2222. ee eee 42 15. Mouth parts of worker.22. 2.2 es) 43 16. Median section through distal half of mentum and base of hgula of “ pworker.202 1 2022. SR 50 17. Epipharynx and labrum of wotker!: 22222. 22 51 18. Sense organs of epipharyux:. 22225 22 0 ee 52 19. Median longitudinal section of head of worker........-..----.-:------ 52 20. Dorsal view of ventral walls of body of worker...-....-...------------ 3 21.. Thorax of worker:. 22....225-22 2 eee 54 22: Lateral view of mesotergum: of worker. = :22-2 225-0. oe 56 23. Thoracie terga of worker....).. 3. 22 ee eee 57 24. Upper part of left mesopleurum of worker. ..-......--. Bone Pn eee: 58 20. Wings of bymenopteras 2.2.2.2 ee == eee Viet oe bee aoe ees 60 26. Basal elements of wings of Hymenoptera’. .-......--...----2--2--=-= 61 27. Median section through thorax of drone: _ 2.5.2.2 -. 25-2 ee 64 28. Internal view of right pleurum of mesothorax of drone. .........----- 65 29. Legs of worker, queem, and drove:-— >>. 52 5-22 = ee ee 67 30. Claws and empodium of foot of werker..- 225-22 ==) ee ee 68 Sl. Tarsal claws of worker, queen, and drome... 2.22 22 eee 69 32. Lateral view-of abdomen of worker, 22-35-4022. 4- eee eee 70 _33. Ventral view of abdomen of worker. 22.29.23 70 34. Dorsal view of abdominal sterna of drone..2._--.-. 22252) eee eee 70 35. Sixth abdominal sternum of worker, queen, and drone...........-.-- 72 36, Semidiagrammatic view of left side of sting of worker...........-..--- 75 37.. Ventral view of sting of worker. . ..J2 2222225003) eee 76 38. Section of small piece of wall of poison sac-. =... 2. t~-.--22e eee eer 39. Sections of alkaline gland of sting? . 22.2 ee. 2-20 2) eee 79 40. Details of sting of worker. 2.2.0. 23.22 oe 2 oo eee 81 41. Tip of abdomen of worker with left side removed..............------ 82 6 ILLUSTRATIONS. a Page. Prwttige=M R ICEMAN OL WOMKEE <= 2 2) as ee es ss SS x 85 = Deiais of _pharyneeal and salivary glands -..2..-.--....:-+-.---..--- 88 . Honey stomach of worker, queen, and drone ..............-.....-.-- 94 . Longitudinal section of honey stomach and proventriculus of queen . 97 . Histological details of alimentary canal of worker --....-...-.:.---.- 103 . Dorsal diaphragm of drone, from one segment........-....--------- 108 Eoitall part ot dorsal diaphragm of drone :.:_ ._.-=2s22:2---==-------- 110 . Pericardial chamber of one segment in worker .......-...---------- 111 Peat eIM Ob WTKR ae oe Te re 113 PA tae me dayeleimUOn Worker... 5.5 2620 7 8 eee. Ye te eek 17 . Nervous system of worker ......-......-- Sys ees 8 Pe ee pice ee 123 . Brain and subcesophageal ganglion of worker .......-...------------ 125 . Horizontal section of compound eye and optic lobe of worker ......- 127 . Histological details of compound eye of worker ..-...-......--.------ 128 MiseNrOnMCiive Olan OL.GrTOne: =. 55.22 0542-255. 22. oss eek ee 133 Phewonurnyearrean. and Sime Of queen : i2..:.-...---.-1:--22252.-: 135 ‘(OV) BJ10e pue (777) JAVOT JO SUI}SISMUOD JOSSOA [VSAOp pue ‘(ydqA pue ydqq) uswopqe jo SUISvVIZABIP [B1JUOA pu [eSsIOp “(0I-T ‘Ogns[) Wesdss [BaqoeA) ‘(OuHl—-TdO) Wojsks SNOAJOU SUIMOYS ‘1ey10M JO ApOq aat}uUe Jo TOl}OOS [BOT}JOA “UBIPpsM ‘[RUIpNIIsuoy—T ‘p17 \S IS W Rain past aS a Gcan (Ha: Li, WAS My ) aff), ey! 1 Yee eee” 4 1U+ AN ‘ ah Yd THE ANATOMY OF THE HONEY BEE. I. INTRODUCTION. The anatomy of the honey bee has been for years a subject of much interest to those engaged in bee keeping both for pleasure and for profit. This interest is due not only to a laudable curiosity to know more of the bee, but to the necessity of such information in order to understand fully what takes place in the colony. All practical manipulations of bees must depend on an understanding of the be- havior and physiology of bees under normal and abnormal circum- stances, and those bee keepers who have advanced bee keeping most by devising better manipulations are those, in general, who know most of bee activity. In turn, a knowledge of bee activity must rest largely on a knowledge of the structure of the adult bee. Studies on the anatomy of the bee have not been lacking, for many good workers have taken up this subject for investigation. The popular demand for such information, however, has induced untrained men to write on the subject, and most accounts of bee anatomy contain numerous errors. This is probably to a greater extent true of the anatomy of the bee than of that of any other insect. Frequently the illustrations used by men not trained in anatomical work are more artistic than those usually found in papers on insect anatomy, and they consequently bear the superficial marks of careful work, but too often it is found that the details are in- accurate. It has therefore seemed the right time for a new presenta- tion of this subject based on careful work. The drawings given in the present paper are original, with the exception of figures 12, 54, and 55, and have been prepared with a thorough realization of the need of more accurate illustrations of the organs of the bee, especially of the internal organs. Mistakes will possibly be found, but the reader may be assured that all the parts drawn were seen. Most of the dissections, moreover, were verified by Dr. E. F. Phillips and Dr. J. A. Nelson, of this Bureau, before the drawings were made from them. An explanation of the abbreviations and lettering is given on pages 139-147. It is hoped that the work will furnish the interested bee keeper with better information on the anatomy of the bee than has hereto- fore been offered to him, that it may provide a foundation for more detailed work in anatomy and histology, and, finally, that it will be | 9 10 THE ANATOMY OF THE HONEY BEE. of service to future students of the embryology and physiology of the bee. With this last object in view the writer has tried to sum up under each heading the little that is at present known of insect physiology in order to bring out more clearly what needs to be done in this subject. II. GENERAL EXTERNAL STRUCTURE OF INSECTS. When we think of an animal, whether a bee, fish, or dog, we uncon- sciously assume that it possesses organs which perform the same vital functions that we are acquainted with in ourselves. We know, for example, that an insect eats and that it dies when starved; we realize therefore that 1t eats to maintain life, and we assume that this involves the possession of organs of digestion. We know that most insects see, smell, and perform coordinated actions, and we recognize, therefore, that they must have a nervous system. Their movements indicate to us that they possess muscles. These assumptions, moreover, are en- tirely correct, for it seems that nature has only one way of producing and maintaining hving beings. No matter how dissimilar two animals may be in shape or even in fundamental constitution, their life processes, nevertheless, are essentially identical. Corresponding organs may not be the same in appearance or action but they accom- plish the same ends. The jaws may work up and down or they may work sidewise, but in either case they tear, crush, or chew the food before it is swallowed. The stomach may ie of very different shape in two animals, but in each it changes the raw food into a soluble and an assimilable condition. The blood may be red or colorless, con- tained in tubes or not, but it always serves to distribute the prepared food which diffuses into it from the alimentary canal. The situa- tion of the central nervous system and the arrangement of its parts may be absolutely unlike in two organisms, but it regulates the func- tions of the organs and coordinates the actions of the muscles just the same. Hence, in studying the honey bee we shall find, as we naturally expect to find, that it possesses mouth organs for taking up raw food, an alimentary canal to digest it, salivary glands to furnish a digestive liquid, a contractile heart to keep the blood in circulation, a respira- tory system to furnish fresh oxygen and carry off waste gases, ex- cretory organs for eliminating waste substances from the blood, a nervous system to regulate and control all the other parts, and, finally, organs to produce the reproductive elements from which new indi- viduals are formed to take the places of those that die. The study of anatomy or the structure of the organs themselves is inseparably connected with a study of physiology or the life functions of the animal. While physiology is a most interesting and important subject, and, indeed, in one sense might be said to be GENERAL EXTERNAL STRUCTURE OF INSECTS. 11 the object of all anatomical research, yet the mere study of the structure of the organs alone, their wonderful mechanical adapta- tions, and their modifications in different animals forms a most fasci- nating field in itself, and besides this it gives us an insight into the blood relationships and degrees of kinship existing between the multitudes of animal forms found in nature. In the study of com- parative anatomy we are constantly surprised to find that structures in different animals which at first sight appear to be entirely differ- ent are really the same organs which have been simply changed in a superficial way to serve some new purpose. For example, the front wing of a bee and the hard shell-lke wing cover of a beetle are fundamentally the same thing, both being front: wings—that of the beetle being hardened to serve as a protection to the hind wing. Again, the ovipositor of a katydid and the sting of a bee are identical in their fundamental structure, differing in details simply because they are used for different purposes. Hence, in the study of anat- omy we must always be alert to discover what any special part cor- responds with in related species. In order to do this, however, it is often necessary to know the development of an organ in the embryo or in the young after birth or after hatching, for many complex parts in the adult have very simple beginnings in an imma- ture stage. Thus it becomes evident that the structural study of even one organism soon involves us in the subjects of anatomy, physiology, and embryology, and, if we add to this a study of its senses, its behavior, and its place in nature, the field enlarges without limit. The student of the honey bee realizes that a lifetime might be spent in exploiting this one small insect. The differences between animals are much greater on the outside than on the inside. In the descriptions of the organs of the honey bee anyone will know what is meant by the “alimentary canal,” the “nervous system,” or the “respiratory system,” but the external parts are so different from those of animals with which we are more familiarly acquainted that no general reader could be expected to know what is meant by the names applied. Moreover, the bee and its allies are so modified externally in many ways that, at first sight, their parts look very different even from those of other insects. Hence, we shall give a preliminary account of the external structure of insects in general, for it is hoped that the reader will then more easily understand the special structure of the honey bee, and that the application of the terms used will appear more reasonable to him. Since all animals originate in an egg, the change into the adult’ involves two different processes: One is growth, which implies merely an increase in size, the addition of material to material; the other is development, which means change in shape and the produc- a2 THE ANATOMY OF THE HONEY BEE. tion of a form with complex organs from the simple protoplasmic mass of the egg. The part of development that takes place in the eggshell is known as embryonic development; that which takes place subsequent to hatching is known as postembryonice development. In insects there are often two stages in the postembryonic development, an active one called the larval stage and an inactive one called the pupal stage. During the first of these the young insect is termed a larva, during the second, a pupa. When there is no resting stage the immature creature is often called a nymph. The final and fully de- veloped form is an adult, or imago. Since this paper is to deal only with the anatomy of the adult, the attractive fields of embryonic and postembryonic development must be passed over, except for a few statements on fundamental embryonic structure, a knowledge of which is necessary to a proper understanding of the adult anatomy. When the embryo, in its course of development, first takes on a form suggestive of the definitive insect, 1t consists of a series of segments called metameres, or somites, and shows no differentia- tion into head, thoracic, and abdominal regions. Typically, each segment but the first is provided with a pair of latero-ventral appendages, hav- ing the form of small rounded protuberances. These appendages are of different sizes and take on different shapes in different parts of the body, for some of them are destined to form the antenns, some the mouth parts, others the legs and perhaps the cerci, while the rest of them eee ae remain very small and finally disappear. What bryo, showing the seg- we know of the embryology of insects is based thoracie and akties on the observations of a number of men who inal regions, and the have worked mostly on the development of dif- segmental appendages. : é : ferent species. Their observations are not all alike, but this is probably due in large part to the fact that the embryos of different insects are not all alike. Embryos have a very provoking habit of skipping over or omitting little and yet im- portant things in their development, but fortunately they do not all omit the same things. Therefore, by putting together all the reliable information we possess, we can make up an ideal embryo which would be typical of all insects. Such a generalized embryo is represented diagrammatically by figure 2. The first six or seven metameres very early begin to unite with one another and continue to fuse until their borders are lost. These consolidated embryonic segments form the head of the adult insect. GENERAL EXTERNAL STRUCTURE OF INSECTS. 13 Observers differ concerning the fate of the seventh segment, but it “is most probable that a part of it fuses with the sixth segment, thus taking part in the formation of the head, and that a part of it forms the neck or some of the neck plates of the adult. The appendages of these first seven segments form the antenne and mouth parts, except one or two pairs that disappear early in embryonic life. It is not certain that the first segment ever possesses appendages, but from it arise the large compound eyes and appar- ently also the upper lip, or labrum (Zm). The appendages of the second segment form the feelers, or antenne (/Ant) of the adult, those of the third (2An?t) disappear in insects, but they correspond with the second antenne of shrimps and lobsters. The appendages of the fourth segment form the mandibles (J/d). Those of the fifth segment (S/in), when present, fuse with a median tonguelike lobe (Zin) of the following segment, and the three constitute the hypopharynx, or lingua of the adult. The next pair (/J/a) form the maxille, while the last (21/x7), or those of the seventh segment, coalesce with each other and constitute the adult labium, or lower lip. The bodies of the head metameres fuse so completely that it is impossible to say positively what parts of the adult head are formed from each. The last, as already stated, possibly takes part in the formation of both the head and the neck. Some embryologists at- tribute the plates which usually occur in this region to the last em- bryonic head segment, while others believe they come from the next seoment following. Sometimes these plates are so well developed that they appear to constitute a separate segment in the adult, and this has been called the microthorax. If this name, however, is given to the embryonic segment from which these plates are said to be derived, it must be remembered that it is not “thoracic” at all and belongs partly to the head. The name cervicum has been ap- plied to the neck region with greater appropriateness since it does not imply any doubtful affiliation with adjoining regions. What we really need, however, is not so much a name as more information concerning the development of the rear part of the head and the neck plates in different insects. The next three segments remain distinct throughout life in nearly all insects, but, since they bear the legs and the wings, they become highly specialized and together constitute the thorax. The indi- vidual segments are designated the prothorax, the mesothorax, and the metathorax. The legs are formed from the embryonic ap- pendages (fig. 2, 7Z, 2Z, 3L) of these segments, but the wings are secondary outgrowths from the mesothorax and metathorax and are, hence, not appendages in the strict embryological sense. The remaining segments, nearly always 10 in number, constitute the abdomen. The appendages of these segments, except possibly 14 THE ANATOMY OF THE HONEY BEE. those of the tenth, disappear early in embryonic life in all insects, except some of the very lowest species, in which they are said to form certain small appendages of the abdominal segments in the adults. An adult insect is often described as being “ divided ” into a head, a thorax, and an abdomen, but this is not true in most cases. While all insects consist of these parts, the divisions of the body are usually not coincident with them. The prothorax in the adult is separated from the head by the neck and is very commonly separated from the mesothorax by a flexible membranous area. On the other hand, the mesothorax and metathorax are almost always much more solidly at- tached to each other, while, in most insects, the metathorax is solidly and widely joined to the first abdominal segment, though in the flies these latter two segments are usually separated by a constriction. In such insects as ants, wasps, and bees a slender, necklike peduncle occurs between the first and second segments of the abdomen, the first being fused into the metathorax so that it appears to be a part of the thorax. This is the most distinctive character of the order Hymenoptera, to which these insects belong. | The body wall of insects is hard on account of the thick layer of chitin which exists on the outer side of the true skin. Chitin is a sub- stance similar to horn, being brittle, though tough and elastic. It gives form and rigidity #o the body and affords a solid attachment for the muscles within, since insects have no internal framework of bones such as vertebrate animals have. The skin between the segments is soft and unchitinized and thus forms a flexible intersegmental mem- brane which 1s often very ample and, in the abdomen, allows each seg- ment to telescope into the one in front of it. The chitin of each segment is not continuous, but is divided into plates called sclerites. The most important of these are a fergum above and a sternum below, but, in the case of the thorax, these two plates are separated on each side by another called the pleurum, which lies between the base of the wing and the base of the leg. Pleural plates are sometimes present also on the abdominal segments. These principal segmental plates are usually separated by membranous lines or spaces, which permit of more or less motion between them. Such lines are called sutures in entomology, though strictly this term should be applied only to the lines of fusion between adjoining parts. The terga, pleura, and sterna of each segment are furthermore subdivided into smaller sclerites, which may be termed tergites, pleu- rites, and sternites, respectively. The sutures between them are sometimes membranous also, but most frequently have the form of impressed lines or narrow grooves. In such cases they are generally nothing more than the external marks of ridges developed on the inside of the body wall to strengthen the parts or to give attachment to muscles. Since these sutures are conspicuous marks on the outside GENERAL EXTERNAL STRUCTURE OF INSECTS. 15 of an insect, they are usually regarded as morphologically impor- tant things in themselves, representing a tendency of the tergum, pleu- rum, or sternum to separate into smaller plates for some reason. The truth about them would appear to be just the opposite in most cases— they are the unavoidable external marks of an internal thickening and strengthening of the plates. In a few cases they may be the confluent edges of separate centers of chitinization. Hence, most of the sutural lines in insects appear to signify a bracing or solidifying of the body wall rather than a division of it. Since the body wall of insects is continuous over all the Santacd it contains no articulations of the sort that occur between the bones in the skeleton of a vertebrate. Although insects and their allies be- long to the class of animals known as the Articulata, yet an articu- late articulation is simply a flexibility—two chitinous parts of the exoskeleton are movable upon each other simply by the intervention of a nonchitinized, flexible, membranous part. While there are often special ball-and-socket joints developed, these are always produced on the outside of the membranous hinge and simply control or limit the movement of the articulation. The head of an adult insect is a thin-walled capsule containing the brain, the ventral head ganglion of the nervous system, the pharynx and anterior part of the cesophagus, the tracheal tubes, and the muscles that move the antenne and the mouth parts. Its shape varies a great deal in different insects, being oval, globular, elongate, or triangular. In some it is flattened dorso-ventrally so that the face is directed upward and the mouth forward, but in most, including the bee, it is flattened antero-posteriorly so that the face looks for- ward and the mouth is directed ventrally. In a few it is turned so that the face is ventral. The walls of the head are usually divided by sutures into a number of sclerites, which in general are located and named as follows: The movable transverse flap forming the upper lip is the labrum. Above it is a sclerite called the clypeus, which is a part of the solid wall of the head and carries the anterior articulations of the mandibles. The clypeus is sometimes divided transversely into an anteclypeus (“clypeus anterior,” “ epistoma ”’) and into a post-clypeus (“clypeus posterior”). Above the clypeus is the front, a plate usually occupying the upper half of the face between the compound eyes and carrying the antenne. The top of the head is called the vertex, but does not constitute a separate scle- rite. The sides of the head below the compound eyes are often sepa- rated by sutures from the anterior and posterior surfaces and are known as the genw. The back of the head is formed by the occiput. which surrounds the large opening or foramen magnum that leads from the cavity of the head into that of the neck. The parts pos- terior to the gene, carrying the posterior mandibular articulations, 16 THE ANATOMY OF THE HONEY BEE. are sometimes separated from both the occiput and the gene and are known as the postgenw. In a few insects, especially beetles, one or two median plates occur in the ventral wall of the head posterior to the base of the labium. These are the gular sclerites. Finally, small plates are sometimes found about the bases of the antenne and be- tween the bases of the mandibles and the gene. The latter have been termed the trochantins of the mandibles. 'The term epicranium is often used to include all the immovable parts of the head, but is frequently applied only to the dorsal parts. Most of these sclerites preserve a pretty definite arrangement in the different orders, and they are probably homologous throughout the entire insect series, though they are in some cases very much distorted by special modi- fications and are often in part or wholly obliterated by the disap- pearance of the sutures. Embryologists are coming to the conclu- sion that the sclerites of the head have no relation to the primitive segments. The latter very early consolidate into a head with a con- tinuous wall, while the sutures defining the sclerites are formed later. Some of the older entomologists were led, from a study of the sclerites, to suppose that the head consisted of a number of seg- ments, but it has been shown that these anatomical segments do not correspond with the embryonic ones. The appendages growing from the front of the face are the antenne (fig. 9A, Ant) or “ feelers’ and consist of a series of joints or segments. At the lower edge of the face is the front lip or labrum (fig. 9A, Im), behind which are the median epipharyna, the paired mandibles (1d) and maxille, the median hypopharynx, and the /abium or under lip. All these organs together constitute what are known as the mouth parts or trophi. They vary greatly in shape and appearance in different insects according to the nature of the food, but their typical form is usually taken to be that shown by the lower insects which feed on solid food and have biting mouth parts. Figure 3, representing the jaws and lips of the common black cricket, is given as an example of generalized insect mouth parts. The labrum (fig. 9A, Zm) is usually a simple transverse flap in front of the mouth, being developed, as already shown, from a similarly situated lobe on the first segment of the embryo (fig. 2, Zm). The epipharynx (fig. 19, phy) is a sort of dorsal tongue, and is situated on the membrane leading into the mouth from behind the labrum. The mandibles (figs. 3A; 9A, Md) are typically formed for biting, being heavy organs situated immediately behind the labrum and working sidewise on a hinge articulation with the head. Their cutting edges are usually notched and toothed, though smooth in the worker bee, “a. oe GENERAL EXTERNAL STRUCTURE OF INSECTS. Vi The maxille (fig. 3 B and B) are complicated appendages in their typical form. Each consists of a principal piece called the stzpes (S¢), which is hinged to the head by means of a smaller basal piece, the cardo (Cd). Terminally the stipes bears an outer lobe, the galea (Ga), and an inner lobe, the dacinia (Zc). On the outer side, at the base of the galea, it carries a jointed appendage called the maazlary palpus (Plp). The hypopharynx (fig. 3 C and D. Hphy) is a median, ventral, tonguelike organ, called also the lingua, situated either on the upper surface of the labium or on the membrane between this organ and the mouth. It is de- veloped principally from a median lobe of the head of the embryo behind the mouth (fig. 2, Zzn), but some entomol- ogists claim that it is compounded of this lobe and two smaller lateral ones developed from the appendages of the fifth embryonic head segment (fig. 2, Slin), the super- lingue. The labium (fig. 38 C and D) consti- tutes the under lip Fig. 3.—Example of generalized insect mouth parts, from of the adult, but if common black cricket (Gryllus pennsylvanicus): A, Mman- z dibles; B, B, maxille, ventral view; C, labium or second IS formed from the maxilla, ventral view; D, labium, lateral view. two appendages of the seventh segment in the embryo, which fuse with each other. For this reason it is often called the second maxille. It consists of a basal submentum (Smt) bearing the mentum (Mt), which in turn carries three parts, a median ligula (Lg) and two lateral palpigers (Pilg). The latter support the /abial palpi (Plp), while the hgula bears four terminal lobes, of which the median ones are called the glossew (Gls) and the lateral ones the paraglosse (Pgl). If we should cut the labium into two parts along its midline we should see that even in the adult stage each half is very similar to one maxilla. The only discrepancy to be noticed in the example given (fig. 3) is that there 22181-—No. 18—10- 2 18 THE ANATOMY OF THE HONEY BEE. is no maxillary palpiger, but many insects possess a corresponding part in the maxilla, frequently distinguished as the palp?fer. The neck or cervicum is usually a short membranous cylinder which allows the head great freedom of motion upon the thorax. In nearly all insects its lateral walls contain several small plates, the cervical sclerites, while, in many of the lower species, dorsal, ventral, and lateral sclerites are present and highly developed. As already stated, the origin of these plates is doubtful. Some entomologists would derive them from the prothorax, others think they come from the last head segment, while still others think that they represent a separate segment. Only pure anatomists, however, entertain this last view and call this supposed segment the “ microthorax,” for embryologists have not yet reported a metamere between the labial segment and the prothoracic segment. Most embryologists who have studied the subject admit that some of the cervical sclerites may be formed from the last embryonic head somite which carries the labium and probably forms a part of the back of the head. Therefore, if it is desirable to retain the word microthorary as a name for a true segment, it can be apphed only to this labial metamere.* The thorax, as has already been stated, is a distinct anatomical region of the body rather than a “ division ” of the body, since it car- ries both the legs and the wings and contains the jarge muscles for each. Since the prothorax does not possess wings, it is not so highly developed otherwise as the two wing-bearing segments, and is, indeed, generally reduced in some ways, some of its parts being frequently rudimentary. Therefore we shall base the following description of a typical segment on the structure of the wing-bearing segments. A typical thoracic segment, then, presents four surfaces, as does also the entire body. These are a dorsum above, a venter below, and a latus” on each side. From these names we have the terms “ dorsal,” 2Jn a former paper on the thorax of insects (Proc. U. S. Nat. Mus., XXXVI, 1909, pp. 511-595) the writer probably drew a too definite conclusion on the subject of the “microthorax.” The origin of the neck sclerites has probably never yet been actually observed. Comstock and Kochi (Amer. Nat., XXXVI, 1902, pp. 18-45), in summarizing the segmentation of the head, accredited the gular and cervical sclerites to the labial segment, but did not recognize the latter as taking part in the formation of the true head capsule. Riley, how- ever, in his study of the development of the head of a cockroach (Amer. Nat., XXXVIIT, 1904, pp. 777-810), states that in Blatta the labial segment does form a part of the back of the head and that the posterior arms of the tentorium are derived from it. Bérner (Zool. Anz., XXVI, 1903, pp. 290-315) and Crampton (Proc. Acad. Nat. Sci. Phila., 1909, pp. 3-54) believe that the cervical sclerites are derived principally from the prothoracie segment. The notion that they constitute a separate segment, the “ microthorax,’” equivalent to the maxilliped segment of the centipedes, has been elaborated principally Ey Verhoeff in his numerous writings on the Chilopoda and Dermaptera. ’ The writer introduces this word here because he knows of no other term applied to the side of the segment in this sense. GENERAL EXTERNAL STRUCTURE OF INSECTS. 19 “ventral,” and “lateral.” The chitinous parts of the dorsum con- stitute the tergum,; of the venter, the sternum, and of the latus, the pleurum. The tergum of the wing-bearing segments usually consists of two plates—a front one or true notum (fig. 4, WN) carrying the wings, and a posterior one, which the writer has termed the postnotum or pseudonotum (PN), having no connection with the wings. The first is often more or less distinctly marked into three transverse parts called the prescutum (Psc), scutum (Sct), and scu- tellum (Scl). In such cases the exposed part of the postnotum is called the postscutellum (Pscl). From either the anterior or the pos- terior margin of the tergum, or from both, a thin transverse plate projects downward into the interior of the thorax for the attachment of muscles. These plates are the phragmas (Aph and Pph). The notum supports the wing on each side by two small lobes, the anterior and posterior notal wing processes (ANP and PNP). Behind the latter is the attachment of the axillary cord (AzC) or basal ligament of the wing. A large V-shaped ridge on the under surface of the notum hav- ing its apex forward is the “ entodor- sum.” (A _ better name would be entotergum.) The pleurum consists principally of two plates, the episternum (fig. 4, Eps) Fic. 4.—Diagram of generalized and the epimerum (Epm) lying before ee re and behind a vertical groove, the pleural suture (PS), which extends from the pleural coxal process (CxzP) below to the pleural wing process (WP) above. The pleural suture marks the position of a heavy internal ridge, the pleural ridge or entopleurum. The epi- merum is connected with the postnotum (PV) behind the base of the wing. These parts occur in almost all insects. In some of the lower ones another plate is present in front of the episternum which may be called the preepisternum (Peps).* Lying along the upper edge of “Objection may be made to the use of the term “ preepisternum” on the ground that it combines a Latin prefix with a word compounded of Greek ele- _ ments. The same may be urged against “‘ prephragma,” “ postphragma,” “ pre- ie, Paraptera,* and “ postparaptera,” words introduced by the present writer in a th former paper on the thorax (Proc. U. S. Nat. Mus., XXXVI, 1909, pp. 511-595). “= However, we are barred from making up equivalent terms with the Greek pre- _ fixes pro and meta because these are used to designate the first and the third 20 THE ANATOMY OF THE HONEY BEE. the pleurum and associated with the under surface of the wing base are several small plates known as the paraptera (P).* Two he above the episternum in front of the pleural wing process and are the episternal paraptera or preparaptera (1P and 2P), while one or occasionally two are similarly situated behind the wing processes and are the epimeral paraptera or postparaptera (38P and 4P). The preparaptera afford insertion for the muscle concerned in the exten- sion and pronation of the wing. The cowa (Cx), or basal segment of the leg, is hinged to the seg- ment by a dorsal articulation with the pleural coxal process (CaP), and by a ventral articulation (7nC) with a plate called the trochan- tin (Tn) lying in front of it and connected above with the lower end of the episternum (#’ps). Hence, while the leg is of course con- tinuous all around its base, by means of membrane, with the body- wall, its movement is limited to a hinge motion by these two special articulations of the chitin. The sternum or ventral plate of the segment is not so complicated as are the tergum and pleurum. It is often divided transversely into three parts, however, and some authors say typically into four. These parts have been named the presternum (Ps), sternum proper (8S), segments of the thorax or their respective parts. Entomologists have already established the system of referring a part to the front or back of any individual segment by the Latin prefixes pre (or. pre) and post as used in “ prescutum,” ‘“ presternum,” ‘ postscutellum,”’ and “ poststernellum.” Furthermore, pre and post are so indiscriminately used in English combined with Latin, Greek, and even Anglo-Saxon words that they may be regarded as general property. Hence, in order not to sacrifice an anatomical system, which certainly needs to be fostered in every way, the writer has preferred to sacrifice strict gram- matical rules by applying pre and post, regardless of the origin of the noun in the case, to designate anterior and posterior parts of the same segment. We already use such hybrid terms as “ presternum,” ‘‘ mesotergum,”’ and ‘“ meta- tergum.” The name “ preepisternum’ has been applied by Hopkins (Bul. 17, Pt. I, technical series, Bur. Ent., U. S. Dept. Agr., 1909) to a part of the mesepister- num of Dendroctonus—a plate apparently not homologous with the preepisternal element of the thorax in primitive insects. *The name “parapterum” is taken from Audouin’s term paraptére (Ann. des Sci. Nat., I, 1824, pp. 97-135, 416-482), and its application, as used by the present writer, is based on Audouin’s definition given in his Chapter III, “ Considerationes generales sur le Thorax,” where he says (p. 122): “ Finally there exists a piece but little developed and seldom observed, connected with both the episternum and the wing. It is always supported by the episternum and is sometimes prolonged ventrally along its anterior margin, or again, becoming free, passes in front of the wing and may even come to lie above the base of the latter. At first we designated this sclerite by the name of Hypoptere but on account of its change of position relative to the wing base we now prefer the name of PARAPTERE.” ‘The first part of his description leaves no doubt that Audouin referred to the little pleural plate beneath the front of the wing which is usually very inconspicuous except in carefully dissected GENERAL EXTERNAL STRUCTURE OF INSECTS. nae | sternellum (Sl), and poststernellum (Psl). In some of the lower insects a plate (a) occurs at each side of the presternum or of the sternum which seems to fall in line with the preepisternum of the pleurum. This has been variously called a part of the presternum, the coxosternum, an accessory sternal plate, and the sternal laterale. The inner surface of the sternum carries a large two-pronged process. called the furca or ento- sternum. This plan of structure for the mesothorax and the metathorax prevails throughout all insects. The honey bee probably —__ ——s presents the greatest de- Emp la parture from it, but even eee er a here the modification consists principally of a suppression of the sutures of the pleurum resulting from a condensation of the parts. The leg (fig. 5) of an adult insect consists of a number of joints or segments. It is attached to the body, as just described, by a thick specimens. In such preparations, however, one finds that there are in most cases two sclerites here instead of one, and, furthermore, that one or oc¢a- sionally two others are similarly situated beneath the rear part of the wing base behind the pleural wing process. The present writer has, therefore, made the term “ paraptera”’ cover this whole row of little plates, distinguish- ing those before and those behind the pleural wing process by the designations given above. In the latter part of Audouin’s definition it would seem that he may have confused the rudimentary tegula as it exists in some insects with the parapte- rum, but even this is not probable since he says it is always connected with the episternum, which is never true of the tegula. In his description of the thorax of beetles, Dytiscus, Carabus, Buprestis, and Curculio, it is evident that he regards the anterior upper part of the episternum as the parapterum fused with the latter plate. In fact, in each case he definitely states that such is the case and, in describing Dytiscus circumflerus, he says (p. 420): * The episternum, the parapterum, and the epimerum all fuse dorsally and constitute a support for the wings and tergum.” While Audouin is undoubtedly mis- taken in this homology, especially in the mesothorax, he at least shows that his “paraptére” is a part of the pleurum. Hence modern writers such as Packard and Folsom who make the term “paraptera’’ synonymous with “teguie” are certainly wrong. The tegula is a dorsal scale or its rudiment at the humeral angle of the wing, while the parapterum is a co-existent scle- rite below this part of the wing base. The present writer agrees with Comstock and Kellogg, who, in their Elements of Insect Anatomy (first edition), define the little sclerite in’ front of the base of the wing in the locust, articulated to the dorsal extremity of the episternum, as the “ parapteron,” though in this insect there are here really two of these parapteral plates instead of one. 99 THE ANATOMY OF THE HONEY BEE. basal joint called the cova (Cx). Beyond this is a ‘smaller joint ealled the trochanter (Tr), this is followed by a long and strong segment, the femur (/), which extends outward from the body, while bending downward from its distal end is the long and slender tibia (Tb), followed finally by the foot, or tarsus (Tar). The tarsus itself consists typically of five small segments of which the last bears a pair of claws (Cla). The under surfaces of the tarsal joints are often provided with small cushions or pads called pulvilli. Those between | the claws are generally specially prominent and are called the empodia (Emp). The leg varies greatly in shape in different in- sects but usually preserves all of these parts. The segments of the tarsus, however, are frequently reduced in number. The adult wing is a thin expanse of membrane supported by hollow branching rods called vezns. It originates as a hollow outgrowth of the body-wall, but soon becomes flattened out dorso-ventrally and the Fic. 6.—Diagram of generalized insect wing and its articulation to first plate (N) of the tergum. contained trachez or air tubes mark out the courses of the veins. These veins form various patterns in different insects, but they can all be derived by modification from one fundamental plan. This plan is shown diagrammatically by figure 6. The first vein, which usually forms the anterior margin of the adult wing, is the éosta (C). The next vein is the swbcosta (Sc), which in typical cases divides into two branches (Sc, and Sc,). The third and usually the principal vein is the radius (f). Tt divides dichotomously into five branches (/?, to &,), the anterior branch of the first fork remaining single. The next vein is the media (J/), which forms four branches (J/, to M,). The fifth is the cubitus (Qu), which again is two-branched. The remaining veins are called the anals and are designated indi- vidually as the first anal (1A), second anal (2A), ete. Several cross-veins of common recurrence should be noted. The first is situated near the base of the wing between the costal and subcostal veins and is known as the humeral cross-vein. A second als GENERAL EXTERNAL STRUCTURE OF INSECTS. 23 occurs between the radius and the media near the center of the wing and is called the radio-medial cross-vein. Another one, the medio- cubital, is similarly located between the media and the cubitus, while a fourth, called the median, occurs between the second and third branches of the media. The areas of the wing surface inclosed by the veins, the cross-veins, and the margins of the wing are known as the cells. A great many different names are applied by different entomolo- gists to the veins of the wings, both of the same and of different insects. The nomenclature here given is the one first consistently applhed by Comstock and Needham and now used by a large number of entomologists working in different orders of insects. The wing is articulated at its base (except in mayflies and dragon- flies) to the anterior and posterior wing processes of the notum (fig. 6, AVP and PNP) and to the wing process of the pleurum (fig. 4, WP) by several smail articular sclerites called axillaries. Two of these, the first (1Ax) and the fourth (44x), form a hinge with the anterior and the posterior notal wing processes, respectively, while the second (2Ax) articulates below with the wing process of the pleurum, constituting thus a sort of pivotal element. The third axil- lary (Aa) intermediates between the bases of the anal veins and the fourth axillary—except when the latter is absent (as it 1s in nearly all insects except Orthoptera and Hymenoptera), in which case it articulates directly with the posterior notal process. The thin mem- brane of the wing base may be called the axillary membrane (Avid). On its anterior edge is a hairy pad, the tegula (7g), which is some- times a large scale overlapping the humeral angle of the wing. The posterior margin of the axillary membrane is thickened and may be ealled the axillary cord (AxC) or basal ligament of the wing. The base of the costa is not directly associated with any of the axillaries, but is specially connected by tough membrane below with the episternal paraptera. The subcosta abuts against the end of the curved neck of the first axillary. The radius is either attached to or touches upon the anterior end of the second. The media and cubitus are usually associated with each other at their bases and also more or less closely with one or two median plates (m) in the wing base. These plates, however, are not of constant shape and occur- rence as are the articulating axillaries. The anals are generally attached to the outer end of the third a which acts as a lever in the folding of the wing. A few insects have a generalized wing almost identical with the diagram (fig. 6), but most of them depart from it in varying degrees. Few go so far, however, as the honey bee, whose venation is very different, but yet the fundamental basal structure is the same even 24 THE ANATOMY OF THE HONEY BEE. here, as will be shown in the Special description of the wing of the bee. The abdomen consists almost always of 10 segments. There are never any more than this number well developed in adult insects, and if there are fewer the reduction is due to a modification of the ter- minal segments to accommodate the external organs of reproduction. ~The posterior opening of the alimentary canal is at the end of the tenth segment, which carries also two small appendages at the sides of theanus. These are called the cerci (fig. 8, Ver). In some insects they are short, styletlike processes, in others they are long and many jointed, while in many they are absent. The cerci are supposed to be developed from the embryonic appendages of the tenth segment, although, on the other segments, these appendages disappear before the embryo hatches, except in some members of the lowest wingless order of insects, which have a pair of cercushke appendages on each seoment of the abdomen. Each abdominal segment presents a tergum above and a sternum below; the former usually also reaches far down on the sides and overlaps the edges of the sternum. In some insects one or more small pleural plates intervene between the tergum and the sternum, but the abdominal pleura are never developed in any way suggestive of a thoracic pleurum. Very frequently there is present an upper pleural plate, or epzpleurite, adjoining the edge of the tergum and a lower, or hypopleurite, adjoining the edge of the sternum. The line separating these two sclerites, however, is horizontal and can not correspond with the vertical suture of a thoracic pleurum between the episternum and the epimerum extending from the base of the leg to the base of the wing. The most complicated structures on the abdomen are the externa organs of reproduction. In the male these serve as clasping organs and take on a great variety of forms in different species. The organs in the female form an ovipositor and are of much more definite and constant structure. | The ovipositor (fig. 8), in its most perfect development, consists of three pairs of long, closely appressed bladelike processes called gonapophyses (1G, 2G,3G). These six pieces fit neatly together and form an organ by means of which the female makes a hole in the ground or in the bark of a tree, or punctures some other insect, and then places her eggs in the cavity thus produced. An interesting fact in this connection is that the sting of a wasp or bee is simply a modi- fied ovipositor. This can be proved by a comparison of the organs themselves or by a study of their development. Each is formed from six little peglike processes that grow out from the sterna of the eighth and ninth abdominal segments of the larva or young soon after hatch- GENERAL EXTERNAL STRUCTURE OF INSECTS. we ing (fig. 7, 7G, 2G, and 3G). At first there is only one pair of these processes on each of the two segments, but those on the ninth soon split each into two, thus producing two pairs on this segment. The opening of the oviduct (OvQ@) is on the eighth segment between the bases of the first gonapophyses. The ovipositor of the longhorned grass- hopper, shown by figure 8, may be taken as a typical example of this organ. The Vi median pair of gonapophyses on the ninth : segment (2G) remain slender and fuse at yy oe @ their bases into a small bulblike swelling open below (ShB). The pair from the X aoe eighth segment (7G) form two long blade- aah like pieces, which fit by sliding articula- An 3G tions upon the lower edges of the corre- aie tie ie sponding second gonapophyses (2G). The male insect and early stage in first can therefore be worked back and Peat Geen tae forth while they are braced and held in _ whieh is formed the ovi- position by the second pair. The third Gauges ie pears gonapophyses (3G), or the outer pair of _ the ninth segment (the left one in figure 8 is shown as if cut off near its base), form two long flat blades which are closely appressed against the outer surfaces of the others. In the detailed study of the bee it will be shown how closely the structure of the sting corre- sponds in every way with that of this ovipositor. Fic. 8.—Example of a swordlike ovipositor, from a longhorned grasshopper (Cono- cephalus sp.), illustrating the fundamental similarity of structure with the sting of the bee, fig. 36. Some entomologists have supposed that the original two pairs of gonapophyses represent the embryonic appendages of the eighth and ninth segments, and they would thus establish a homology between the ovipositor or sting and the legs and mouth parts. It has been shown, however, that the true appendages of the abdominal segments disappear in embryonic life while the gonapophyses appear much later, during early nymphal or larval life. Furthermore, each pair 26 THE ANATOMY OF THE HONEY BEE. — of gonapophyses arises in a median depression on the ventral side of the segment while the true appendages are latero-ventral. Hence, the evidence is very much against this theory and the gonapophyses appear to be special secondary processes of the body wall. All insects do not have ovipositors of the sort described above. Flies, beetles, moths, and butterflies do not. Such insects simply drop their eggs from the oritice of the oviduct or deposit them in masses upon the external surfaces of various objects. In some of the flies, however, the terminal segments are long and tubular and entirely telescoped into one another. They are hence capable of being protruded in the form of a long tapering tube having the open- ing of the oviduct near the tip. This enables the insect to deposit its egos in deep crevices, but the structure is not a true ovipositor—it is simply the abdomen itself stretched out. Insects breathe through a-series of small holes situated along each side of the body. These breathing apertures are called spiracles and they lead into a system of internal air tubes called trachew. There are nearly always 10 spiracles present on each side of the body. Two are located on the thorax, the first between the prothorax and the mesothorax, the second between the mesothorax and the metathorax, while the other eight are situated on the first eight abdominal seg- ments. Some embryologists believe that the spiracles of the pro- thorax move forward in early embryonic life and unite with each other in front of the hypopharynx to form the salivary opening, their tracheze constituting the salivary ducts. After this review of the general external structure of insects we may proceed to a more detailed account of the parts and organs of the honey bee. Ill. THE HEAD OF THE BEE AND ITS APPENDAGES. The head of an insect, as already explained, is a composite organ formed of six or seven primitive segments, each of which, except the first, typically bears a pair of appendages (fig. 2). The antenne are developed from the embryonic appendages of the second segment, the mandibles from the fourth, the maxille from the sixth, and the second maxille, or labium, from the seventh. The appendages of the third segment disappear in early embryonic life while those of the fifth segment, when the latter is present, fuse with a median tonguelike lobe of the next segment to form the hypopharynx of the adult. 1. THE STRUCTURE OF THE HEAD. The general appearance and outline of the head of a worker bee are shown from before and behind by figure 9, A and B. In facial view the head is triangular, with the apex below. The side angles THE HEAD OF THE BEE AND ITS APPENDAGES. 27 are rounded and capped by the large compound eyes (#’). In the opposite direction the head is very much flattened, the greatest diame- ter being crosswise through the middle of the eyes. The face is con- vex, while the posterior surface is somewhat hollowed out and fits snugly upon the anterior end of the thorax. The large lateral eyes (fig. 9 A, 2) are called the compound eyes, because each is composed of a large number of separate eye elements forming the little hexagonal facets visible on the surface. All of these facets together constitute the cornea, or the transparent outer surface of the eye, which in the bee is densely clothed with long hairs. The dark color of the eye is located in the deeper parts, but these will be described in the section dealing with the nervous system. On the Bi) =_A — < BE , Zz 2 =~ PrbFs = =, y es : C Z . = ZB Ee . —A = AR 3X = Ss = E=_— sy Md a——>—_ ——S SS ae’. | aS / SS t —S => weSS5 ( ———rw ||\\\ \ —— HA\\\} \ =) {\\\\) \ = f\\\\ mS =) \\\\\ “Mx Plp AA i | 7 AVA) Fig. 9.—A, front view of head of worker bee with mouth parts (Prb) cut off a short distance from their bases; B, corresponding view of posterior surface of head. top of the head between the compound eyes are the three simple eyes, or ocelli (O), arranged in a triangle with the median ocellus in front. Between the lower halves of the large eyes and near the center of the face arise the antenne (Anz), each of which is inserted into a small, circular, membranous socket of the head wall, and consists of a long, basal, 1-segmented stalk carrying a terminal 11-jointed arm movably articulated to the stalk and generally hanging downward from it. (In the drone the terminal arm consists of 12 joints.) The mouth parts are attached at the lower part of the head, and consist of the mandibles (Md) laterally and the maxille (Mz) and labium (Lb) mesially. The latter two include the set of elongate bladelike organs surrounding the protrusible “ tongue,” which to- gether constitute what is commonly known as the proboscis (Prb). 28 THE ANATOMY OF THE HONEY BER. When not in use the parts of the proboscis are bent back beneath the head. By referring to figure 9B, giving a posterior view of the head, it will be seen that the basal parts of both the maxille (Sf) and the labium (J/¢) are suspended in a large hollow on the back of the cranium. This may be called the cavity or fossa of the proboscis (PrbFs). Between the mandibles on the front of the head (fig. 9A) is a transverse movable flap, the labrum (Lm), attached to the lower edge of the front wall of the head and constituting the upper lip. The mouth (J/th) hes behind the labrum and the mandibles close beneath it. Below the antennal sockets is a transverse, slightly arched suture (a) which turns downward on each side and extends to the inner angles of the bases of the mandibles. The area bounded by this suture is the clypeus (Clp) and the suture itself may be called the clypeal suture. | On the posterior surface of the head (fig. 9B) is seen the pen- tagonal foramen magnum (for) by means of which the cavity of the head communicates with that of the thorax and through which > pass the nerves, cesophagus, blood vessel, and tracheal tubes. A small rod (ten) inside the head arches transversely over the fora- men magnum, cutting it into a dorsal and a ventral half. At each side of the foramen is a large pit (¢) which marks the base of an internal chitinous beam of the head known as the mesocephalic pillar. The opposite end of this pillar unites with the front wall of the head on the clypeal suture below the antennz, where it produces another smaller pit (0). Below the foramen magnum and separated from it by a wide trans- verse bridge of the cranial wall is seen the large fossa of the proboscis — (fig. 9B, PrbF's) having the shape of an inverted U. The side walls of this cavity are chitinous and from their upper edges are suspended the maxille, while the base of the labium is contained in the mem- branous floor of the fossa. The base of the labium projects from the head beneath or behind the mouth opening and its dorsal surface forms the floor of a preoral cavity surrounded by the bases of the mouth parts and jabrum. It will be seen from the above description that the head wall of the bee contains no suture except that bounding the clypeus and the one which separates the labrum from the latter. Many of the higher insects have the head wall completely continuous, showing no diyision at all into sclerites, but, in such forms as a grasshopper or cockroach, and, in fact, most of the lower insects, the head as well as the other parts of the body is made up of a number of plates. Hence this may be regarded as the primitive condition, and it is presumed that the head of the bee has been produced from one whose wall was divided by sutures into a number of distinct parts. Therefore the different THE HEAD OF THE BEE AND ITS APPENDAGES. 29 regions of the bee’s head may be named according to the sclerites with which they correspond in other insects. Thus, the part of the face above the clypeus and between the compound eyes may be called the front (fig. 9A, Ft), the parts below the compound eyes the genw (Ge), and the top of the head the vertex (Va). The area on the back of the head around the foramen magnum may likewise be termed the occzpital region (fig. 9B, Oc) and the parts be- hind the gene and the lower halves ef the compound eyes the postgene (Pge). The worker, queen, and drone differ conspicuously in the shape and size of the head, as will be seen by comparing A, B, and C of figure 10. In these drawings the front has been removed in order to show various internal parts, which will be described later. While the head of the worker (A) is triangular in facial view, that of the queen (B) is more rounded and wider in proportion to its length. The head of the drone (C) is much larger than that of the female and is nearly cir- cular in outline. In shape the head of the queen is intermediate between that of the worker and that of the drone, but in size it is somewhat smaller than the head of the worker. The eyes (#) of the worker and queen are about equal, but those of the drone are enormously enlarged and are broadly contiguous on the vertex and the upper part of the front. On this account the ocelli (OQ) of the drone are crowded down on the front nearer the bases of the antenne and the frent itself is very much narrowed above. The antenne of the drone consist of 13 segments, while those of the females Fig. 10.—A, anterior view of head of worker, with front, antenne, and proboscis removed; B, correspond- ing view of head of queen; C, same of drone. have but 12 segments. The mandibles are largest proportionately in the queen and are very small in the drone. Those of the worker have a smooth terminal edge, while this edge is notched in the queen and the drone. The parts of the proboscis are much longer in the worker 30 THE ANATOMY OF THE HONEY BEE. and capable of much more action than in the queen and drone, which are almost entirely dependent upon the workers for their food. The internal structure of the cranium may be studied best in a longi- tudinal section of the head (fig. 11). In order to prepare a section for this purpose imbed the head in paraffin and then carefully slice off one side with a sharp knife or razor just outside of the bases of the mandible and antenna. Holding the remainder in the block of paraffin or fastening the whole in a dish of water or alcohol, care- fully dissect away the soft parts from the head cavity so as to expose Eps = Fic. 11.—A, longitudinal section through head of worker between the median plane and outer edges of mandibles (Md) and antenne (Ant) of left side, all internal soft parts removed; B, corresponding section through head of drone, except that the pharynx (Phy) and csophagus (dG) are not removed. the internal chitinous parts shown in figure 11 A and B. These figures, however, represent a slice of the head taken from between the median plane and the outer edges of the antennal and mandibular bases of the left side. Thus only the parts on one side of the mid- line are shown. Figure A is from a worker and Figure B from a drone. In the latter the pharynx and esophagus are retained and the neck is not removed. Figure 20 shows the head cut open from above and the mouth parts removed. A specimen so cut and bviled a short time in caustic soda or potash to remove the soft parts will be found a valuable adjunct to this study. _—_ THE HEAD OF THE BEE AND ITS APPENDAGES. 31 The principal parts of the internal skeleton of the head, or eato- cranium, consist of two large, oblique, strongly chitinous bars form- ing a brace between the anterior and the posterior walls of the head (fig. 11 A and B, Zen, showing the parts on the left side only, and fig. 19, Ten). ‘These bars have been named by Macloskie (1881) the mesocephalic pillars. As already pointed out the base of each is marked externally by a conspicuous pit (fig. 9 B, c) laterad of the foramen magnum, and its facial end by a smaller pit (fig. 9 A, 0) in the clypeal suture near the upper end of each side of the latter. The bases of these pillars are connected by the slender bar (fig. 11 A, ten), already noticed, arching over the foramen magnum (fig. 9 B, ten). This bar and the two pillars represent what is called in other insects the tentorium. In the embryo the tentorium is formed from tubular ingrowths of the head wall which unite internally and assume different shapes in different insects. Since the air tubes of the body also first appear as tubular ingrowths of the body wall, some entomologists have supposed that the hollow tentorial in- erowths of the head represent the spiracular tubes of the head which are, otherwise, lacking. However, there is not sufficient ev1- dence to support such a view as this, and there is no reason why the tentorium should not have been originally designed simply to give greater rigidity to the walls of the head where the latter support the appendages. The usual form of the tentorium in the lower insects is that of an X, with a large central body, situated like a brace across the lower part of the head, having two of the arms directed anteriorly and laterally and two directed posteriorly and laterally, and while the former are said to be ingrowths from the mandibular segment, there is some difference of opinion concerning the segment to which the latter belong. Riley states that they are formed in the labial seg- ment of the cockroach and Carriere and Burger describe the same thing for the mason bee. Other authors have ascribed them to the maxillary segment, but they may, in later stages, he in this segment and thus appear to belong to it, while they originated in the one following, having moved forward on account of the condensation of the back part of the head. The tentorium of the honey bee, consisting as it does of the two great mesocephalic pillars (fig. 11 A and B, Zen) and the small arched bar (ten) is so highly modified that it is hard to see just how its parts are to be homologized with the parts of an X-shaped tentorium. Probably the two pillars repre- sent the separated halves of the X, while the slender arch is an addi- tional structure. In any case we have not enough evidence to war- rant us in regarding the tentorial invaginations as modified trachee, or their external pits as rudimentary spiracles. Similar processes extend inward from the walls of the thorax to strengthen it or to give attachment of muscles. Such processes in general form the 32 THE ANATOMY OF THE HONEY BEE. - entoskeleton and are individually called apodemes. Those of the head constitute the entocranium, those of the thorax the entothoraz. The side walls of the fossa of the proboscis form two high, thin, vertical plates, as seen from the interior of the head (fig. 11), in front of the mesocephalic pillars. The posterior edge (d) of each of these plates is so much thicker than the rest of it in the worker that it appears at first sight to be a separate rod. Its upper end projects above the body of the plate as a free arm (e) to which is articulated the basal piece of the maxilla (Cd). It thus constitutes the mawillary suspensorium. (Macloskie includes under this term both the arm of the cranial wall and the cardo of the maxilla.) The head of the drone (fig. 11 B) presents, besides the parts de- scribed, a thin plate (f) depending from the vertex of the cranium along the line between the compound eyes. Besides these apodemes of the cranial wall itself there are others which project into the head.cavity from the bases of the appendages to afford points of insertion for their muscles. These are specially developed in connection with the mandibles and will be described in the discussion of these organs. Still other internal chitinizations are developed in the walls of the pharynx, but these hkewise will be described later. 2. THE ANTENNZ AND THEIR SENSE ORGANS. The antennee of the bee are the two slender, jointed appendages movably attached to the center of the face, where each is inserted into a circular membranous area or socket just above the upper part of the clypeal suture. Their general shape and position are shown by figures 9 A, 11 A, and 19, Ant. Each is seen to consist of two parts, forming a prominent elbow with each other, and usually so held that the first or proximal part extends outward and upward from its frontal attachment and carries the other in a pendent posi- tion from its distal end. The first part thus forms a basal stalk, called the scape (figs. 9 A; 19, Sep), consisting of a single joint inserted into the arttennal socket of the front by a prominent basal — condyle bent toward the face. This articular knob is attached to © the rim of the socket by a circle of membrane, but it is also pivoted on a slender peglike process projecting upward from the lower edge of the socket. Hence, while the flexible membrane allows each antenna to revolve freely in any direction, the latter is at the same time held firmly in position by the pivot. The antennz are moved by special sets of muscles inserted upon their bases within the head. The second or distal division of the antenna is cylindrical and longer than the first, forming a flexible fagellum (fig. 9 A; 19, FZ) hanging downward from the distal end of the scape. It is composed of 11 THE HEAD OF THE BEE AND ITS APPENDAGES. ae small joints in the worker and queen and of 12 in the drone. The male antenna thus consists of 13 joints in all, while that of the female has but 12. The first joint of the flagellum is freely articulated to the scape, but the others do not have much play upon one another, though they give flexibility to the flagellum as a whole. Each antenna is a hollow tube containing the large antennal nerve, minute extensions of the tracheal system, and the small muscles which move the segments upon one another. Popularly the antenne of insects are known as the “ feelers,” be- cause they are constantly moved about in all directions with a nervous kind of motion as if the creature were feeling its way along by means of them. In fact “feelers” is a better name for these appendages than the scientific term, for there can be no doubt that the sense of touch is very highly developed in them and that by means of them insects acquire a great deal of information concerning their surround- ings and their companions. Moreover, a large mass of evidence derived from experiments shows unquestionably that the organs of smell also are located upon the antenne in a great many if not all insects, while some investigators believe that in some species they carry in addition the organs of hearing. The study of the senses of insects is a most elusive subject, and becomes more so the more we ponder on the results of experiments. In the first place, 1t is manifestly impossible for us to acquire any real knowledge of an insect’s sensations, for what is to us an odor, a taste, a color, or a sound may be something quite different to such a differently organized creature. We can, however, by experiments determine that some things which give us the sensation of an odor are perceived also by insects when placed near them. Also it can be shown that some of them distinguish substances of different taste in- their food, and hkewise that they perceive movement and distinguish the colors and in a vague way the outlines of objects. Furthermore, it is known that some of their perceptions are more delicate than ours, and that some insects at least see color where we see none. They may even possess senses of which we have no conception. Hence, while it can be positively stated that insects perceive differ- ences of touch, taste, smell, sound, and light, and act accordingly, we can not say what the sensations they acquire are lke. In fact we do not know that they have conscious sensations at all. What looks hke an action due to intelligent perception may be purely a reflex one, unaccompanied by any sensation. This of course involves the ques- tion as to whether such creatures or insects are possessed of conscious- ness or not—a question which can not be answered one way or the other. Understanding, then, that our knowledge of insect senses amounts only to this, that what gives us the sensation of light, sound, taste, 22181—No. 18—i10——3 84 THE ANATOMY OF THE HONEY BEE. touch, or smell makes also some sort of an impression on the insect and varies in degree and kind much as it does in us, we may go on to a study of the senses located on the antenne. Here, again, however, we are confronted by a difficulty, for while, at first thought, it seems very easy to hold some strong-smelling sub- stance near the antenne of a beetle, ant, or bee and observe the evident displeasure with which the creature turns away, yet we may be en- tirely wrong if we conclude that the insect “smells” the substance that repels it. Strong-smelling, volatile liquids may simply produce pain in some of the delicate nerve endings of the antenne. Some other kind of a being, experimenting on our senses, might close up our nose and mouth and prove that we smell by means of our eyes on observing the blinking we should perform when strong formalin or ammonia was held close to the face. Furthermore, irritant gases and volatile liquids affect the mucous membranes of our noses and throats in a way quite independent from the odor that we perceive, — and there is no reason why the same may not be true of insects. As pointed out by Forel, experiments on the sense of smell should be made with odorous substances that the insect meets with in a state of nature, which would be principally the materials it feeds on. In- sects are indifferent to almost every mildly odorous substance not used as food, which, however, does not prove that they do not smell them. Again, in many cases, it would be difficult to decide whether the re- sults of an experiment should be accredited to smell or sight. For example, every bee keeper knows that hungry bees are attracted to honey a long distance from their hives, and it would seem almost self- evident that they are guided by a sense of smell. Yet one might con- tend that they find the honey by sight, as, indeed, is claimed by a number of entomologists who have made experiments on the olfactory powers of bees. This question has been decided in some other insects by painting the eyes with some opaque substance or by removing the antennze, but the evidence is not conclusive on either side in the case of bees. Experiments made by a large number of competent investigators, including Lubbock, Schiemenz, and Forel, have proved conclusively that the organs of the sense of smell in insects are located principally on the antenne. The most interesting of these experiments are per- haps those which Forel (1903) made on carrion-feeding beetles. He found the dead and putrid bodies of a hedgehog and a rat infested by a swarm of these beetles belonging to several genera. He collected more than 40 specimens from the carcasses and removed their an- tenne. Then he placed them all at one place in the grass and moved the dead bodies to a distance of 28 paces from the beetles where he concealed them in a tangle of weeds. Examination the next day bisects THE HEAD OF THE BEE AND ITS APPENDAGES. 35 revealed the fact that not one of the mutilated beetles had found the carcasses. Repeated experiments gave the same results—no beetle without its antenne was ever found on the dead animals, although at each examination new individuals of the several species were present. It might be supposed that the mutilation itself distracted the beetles to such an extent that they did not care to eat. In order to test this point Forel next cut off all the feet on one side of the body from a dozen intact beetles and changed the location of the dead bodies again. The next day five of this lot were found on the carcasses. The same results have been obtained from experiments on other insects. Ants distinguish between their comrades and enemies by means of their antennal sense organs. Males of the silkworm moth and many other moths and butterflies perceive the presence of the females and are guided to them by an evident sense of smell located on the antenne, for they fail completely te find them when these appendages are removed, although one immediately recognizes a female when placed in contact with her. Similar experiments have been made on the bee, testing the ability of the workers to find honey hidden from their sight. The results, according to Forel, seem, curiously enough, to indicate that bees can perceive odors but a very short distance from their heads. Forel found that hungry bees in a cage would pass and repass hundreds of times within a few millimeters of some honey concealed from their sight by a lattice without discovering it. They ate it greedily, how- ever, when the lattice was removed, though it had been perfectly accessible to them all the time. Forel believes that “* bees guide them- selves almost exclusively by vision,” and Lubbock holds the same opinion. At the same time it would probably be a very difficult mat- ter to convince many practical bee keepers that bees do not * smell ” from long distances. It is a well-known fact that at times when nec- tar is scarce bees are attracted in large numbers to the houses of an apiary where honey is stored, though, when the natural flow is suf- ficient, they pay no attention to it. Tests of the olfactory sense should undoubtedly be made under natural conditions. Bees inclosed in a box with some honey concealed from their sight might not be able to locate it in such close quarters though they might be smelling it all the time. An odor in a room may so fill the air that it does not seem to come from any particular direction and we ourselves would have to exert our intelligence to discover its source. While, then, it does not seem probable that bees have such limited olfactory powers as some investigators claim their experiments indi- cate, it may be accepted as proved that the organs of smell are located principally on the antenne. It has already been stated that the sense of touch also is very highly developed on these organs, although in a less sensitive degree it is distributed over most of the other parts of 86 THE ANATOMY OF THE HONEY BEE. the body. It is again specially developed on the palpuslike append- ages of the sting. (See figs. 36 and 37, StnPlp.) Sections of a bee’s | antenna show that there are on its surface a great number of minute structures of sev- eral ditierent kinds, though all apparently are to be re garded as modified hairs, which are undoubtedly the sense organs. Now the diffi- culty arises of deciding which of these to assign to the sense of touch and which to the sense of smell. Different au- thors have made such differ- ent interpretations of the sense organs of insects that the student attempting to get information on the subject from books must soon be dis- couraged by their conflicting statements. But- it must be realized that only intelhgent guessing is possible where several senses are located on the same part. In the case of the bee some authors have ascribed even a third sense, that of hearing, to the an- tenne, but there is little evi- dence that bees possess the ne power of hearing. The senses Fie. 12.—Antennal hairs and sense organs of taste and touch are Pe (after Schiemenz). A, example of antennal sessed by the mouth parts, hairs dtr “netted "cate, (CH) Ot and some entomologists think containing prolongation of special cell (cv); that they contain organs of c, D, sualght and corved tactile Bel °O5 sanell also, ‘Thilg aa (Vv); E, conical hair (Hr) sunken in a pit of sight are apparently the (Pt) of the cuticle, probably an _ olfactory only ones that can not be con- organ; F, closed sac shut in by thin disc ; (Ar) on surface of antenna and containing a fused with some other sense. nection NOS en merwe Sy hie, Chest aces antennal sense organs of the bee is that of Schiemenz (1883), whose drawings are here reproduced (fig. 12) and whose text is the basis of the following descriptions. The organs consist, as before stated, of modified hairs and their basal Hr. il-cx * ” tad ad io THE HEAD OF THE BEE AND ITS APPENDAGES. SW insertions which are connected with the ends of nerve fibers. Some of them stand exposed on the surface of the cuticle while others are sunken into, or entirely concealed within, pits of the integument. In addition to these, there are two other kinds of special hairs on the antenne which have no nerve connections, while, finally, the ordi- nary hairs, such as are found on all parts of the body, occur also on them, especially on the scape. The special hairs not provided with nerve endings are of two sorts. One is a solid curved or hooked hair (fig. 12 A, Hr) which is simply articulated into a socket of the cuticle (C7/), while the other (B) is hollow and is situated over a channel through the cuticle, and contains a prolongation of a specially enlarged epithelial cell (Cl) lying beneath it. These hairs can not be regarded as sensory, since they have no communication with the central nervous system, and it is not clear just what purpose they do serve. The simplest sensory organ is a short, hollow, conical hair (C, Hr) arising directly from the surface of the cuticle, over a wide opening through the latter, and containing the end of a sensory cell (Cl) connected with a nerve fiber (Vv), which goes into the main trunk of the axial antennal nerve. A modified form of this organ consists of a curved hair (D, H7) set into a small depression over the cuticular channel. Such hairs are probably tactile in function; that is to say, by means of them the bee can perceive that its antenne are in contact with some surface. The general integument is too thick and dense to allow of any sort of delicate touch sensation being communicated through it, but if one of these movable hairs brushes against an object the nerve within it must be at once stimulated. Tactile or touch hairs are distributed especially over the outer sur- face of the antenne and at its apex, but occur also scattered over the other parts of the body and on the mouth parts. Microscopic sections of the antenne reveal still other organs which are not so apparent on the surface as the hairs just described. One of these is shown at EI of figure 12. It consists of a small pit (Pt) in the integument, widened basally, and having a small papilla on its floor, in whose summit is the opening of a still deeper cavity which also expands toward its deeper end. This inner cavity is almost filled up by a conical plug (777) which arises from its floor and ends just below the aperture into the outer pit. The plug con- tains a thick nerve ending which arises from a ganglion cell con- nected with the antennal nerve by a nerve fiber. Ten or more of these sense organs occur on the terminal and the first three segments of the flagellum. It is evident that each is simply a sensory hair which has been doubly sunken into a cavity of the integument. woo THE ANATOMY OF THE HONEY BEE. As before stated, it has been conclusively proved by several investi- gators that bees perceive odors, and it is said that if the antenne are covered with shellac, bees can distinguish between distasteful substances only by means of the proboscis. Schiemenz and most other writers on the subject therefore conclude that the sunken cones are the organs of smell, since, being below the surface, they could not be organs of touch. Some other authors, however, among whom are Cheshire, regard these inclosed cones as hearing organs. They sup- pose that the sound waves of the air enter the pit, as into an ear cavity, and these set up a vibration in the cone which stimulates the attached nerve ending. However, the appearance of one of these cones would suggest that it is too stable a structure to be affected by sound waves, so the olfactory theory seems much more probable. Finally, Schiemenz describes the most specialized of all the anten- nal sense organs as a closed cavity (P#) in the cuticle (C77) extend- ing into the hollow of the antenna as a long, curved, tapering sac. This is shown at F of figure 12. A nerve (Vv) enters the lower extremity of the pouch, expands slightly into a nucleated ganghon cell (CZ), and then extends toward the top as a delicate spindle drawn out into a fine tapering point. The surface covering of the pit is a thin layer of chitin presenting several concentric light and dark rings surrounding a central disc (Av). Sections show that this appearance of rings is due to circular thickenings of the membrane, and Schiemenz points out that the central disc is probably a modi- fied hair, while the whole structure is to be regarded simply as a modification of a tactile organ such as that shown at D with the nerve-ending and its ganglion inclosed in a sac. These organs are most abundant on the antennxze of the drones, where they are situ- ated, especially on the under surface, so close together that but little space is left between them for the tactile hairs, while in the workers and queens they are farther apart and are interspaced with many tactile hairs. Hence, whatever sense they accommodate must be much more highly developed in the males than in the females. Schiemenz described these organs, as well as the sunken cones, as organs of smell. He ascribed only the senses of touch and smell to the antenne, and both Cheshire and Cowan concur in his view of the closed pits. Arnhart (1906), however, argues that an organ of smell must be open to the air in order to permit the ingress of odor par- ticles. Such an organ is constituted by the sunken cones, but the closed pits have nothing to recommend them for an olfactory fune- tion. Arnhart then further points out that the buried sacs, inclosing a delicately poised nerve-ending and covered by an external tym- panum, have all the mechanical elements of an organ of hearing. He finally argues that bees must hear, since they produce special sounds such as the piping of the queens, and that, since no possible THE HEAD OF THE BEE AND ITS APPENDAGES. 39 organs of hearing have been discovered on any other part of the body, some of the antennal sense organs must be auditory in function. His conclusion from these premises is, of course, inevitable that the closed sacs on the antenne are the hearing organs of the bee. What invalidates the argument, however, is the fact that no one has yet produced any actual evidence that bees perceive sound. The following, then, may be stated as a general summary of the evidence concerning the antennal senses and their sense organs in the bee: (1) The antenne are highly sensitive to touch and are the seat of the sense of smell. (2) They are covered by several kinds of minute structures which are modified hairs containing special nerve-endings. (3) By inference, it would seem certain that these are the sense organs, but we can only form an opinion, based upon their structure, as to which are tactile and which olfactory. (4) One set of organs does not appear to belong to either of these categories and their structure suggests an auditory function, but, in the absence of evidence that bees hear, the purpose of these organs must be re- garded as problematical. 3. THE MANDIBLES AND THEIR GLANDS. The mandibles (fig. 9 A, J/d) are the dark, strongly chitinous appendages of the head, commonly called the jaws, situated at each side of the mouth, anterior to the base of the proboscis. In all in- | sects with biting mouth parts the jaws work sidewise, each being attached to the head by an anterior and a posterior articulation. They can thus swing in and out on a longitudinal axis in such insects, as the bee, that carry the head with the mouth directed downward, or in the same way on a vertical axis in those that carry the head with the mouth forward. Both mandibular articulations are of the ball-and-socket type, although in the bee the socket is a very shallow one, the anterior consisting of a condyle on the outer angle of the clypeus fitting against a facet on the mandible, and the position of a facet on the lower edge of the postgena receiving a condyle from the mandible. The motion of the mandible is thus reduced to a hinge-joint move- ment, and, on this account, insects can only bite and crush their food; they can not truly chew it, since their jaws are incapable of a grinding motion. Each mandible is, of course, as pointed out in the introduction, really suspended -from the head by a continuous membrane between its base and the cranium, being simply a modified saclike outgrowth of the head wall. The two articulations are pro- ductions of the chitin on the outside of this membrane. Figure 9 A shows the location and shape of the mandibles (J/d) of the worker as seen in a facial view of the head. Figure 11 A AO THE ANATOMY OF THE HONEY BER. shows the appearance of the left mandible in side view, while the right one 1s shown detached from the head in figure 13 A. The mandibles differ conspicuously in size and shape in the three forms of the bee as already described and as shown in figure 10 A, B, and C. That of the worker is hollowed out somewhat on the distal half of its inner face (fig. 18 A, J/d) forming a spoon-shaped organ, the edge of which is smooth and rounded. The mandibles of both the queen (fig. 10 B) and the drone (C), however, are pointed at the apex and have a conspicuous subapical notch. Those of the drone are smaller than those of either form of the female, but appear to be especially small on account of the great size of the drone’s head. The mandible of the worker is undoubtedly to be regarded as the special- ized form, since the notched mandible of the drone and queen is of the ordinary Hymenopteran type. Both the drone and the queen are, under normal circum- stances, fed almost entirely by the workers, and they probably never have any use for their Jaws as feed- ing organs. The queen needs her large, sharp- pointed mandibles for bit- Fig. 13.—A, right mandible of worker, anterior view, with extensor and flexor muscles (H#Mcl Mg her way out of the and RMcl) and mandibular glands. (14M@dG1) at- thick wax cell in which tached; B, corresponding view of mandible of : drone, with muscles cut off a short distance from she IS reared, but the Bhetr bases. drone, on the other hand, being reared in an ordinary cell resembling that of a worker, except in size, is easily able to cut through the thin cell cap with his com- paratively weak jaws. The workers, however, have numerous uses for their mandibles, such as biting through the cell caps, eating pollen, and modeling wax. The last is the especial function of the worker mandible, and probably it is to accommodate this pur- pose that it has acquired its specialized spoonlike shape. : Each mandible is moved by two sets of muscles within the head. The outer one constitutes the extensor muscle (fig. 13 A, HJfcl) and the inner the flexor muscle (RMcl). The latter is the stronger of A THE HEAD OF THE BEE AND ITS APPENDAGES. 41 the two, since all the work of the mandible falls upon it. the extensor being used simply to open the jaw. While these muscles have their origins on the walls of the head, they are not inserted directly upon the mandibles, but on large apodemes (fig. 138 A, HAp and RAp) attached to the edges of the mandible. A gland opens at the inner margin of each mandible between the anterior articulation and the base of the apodeme of the flexor muscle (fig. 13 A and B, 7J/dG/). In the worker it consists of a large sac covered with secreting cells lying within the front part of the head between the clypeus and the compound eye (fig. 10 A, 1IMdGl). These mandibular glands may be most easily studied by removing the front as shown in figure 10 A, B, and C. In order to do this, pull the head from the thorax and allow the prothoracic legs, which will usually come off with the head, to remain attached to it. Next melt a small hole in the bottom of a paraffin dish with a heated needle and fasten the head face upward into this, the attached legs helping to anchor the head in the paraffin. Cover the specimen with weak alcohol and by means of sharp needles remove the part of the front on either side between the ¢lypeus and the lower half of the compound eye in the worker and drone and the entire front of the queen. In figure 10 the whole front is removed in all three forms in order to expose other internal parts of the head. The mandibular gland (7J/dG7) is of greatest size in the queen (fig. 10 B), though it is large in the worker (fig. 10 A and fig. 13 A), but it is reduced in the drone (fig. 13 B) to a very small oval sae, which is hidden by another gland (2G/) in front (fig. 10 C). It was first described by Wolff (1875) as an olfactory mucous gland (Piech- schleimdriisse) and was supposed by him to secrete a liquid which was poured upon the roof of the mouth in order to keep this surface, on which Wolff thought the olfactory organs were located, in a moist condition capable of absorbing odor particles. There is absolutely no evidence, however. of the presence of organs of smell in the mouth, and furthermore, as pointed out by Schiemenz (1883), the gland varies in the three forms of the honey bee according to the size of the mandible, which is proportionately largest in the queen and smallest inthe drone. Of the three, we should expect the drone or the worker to have the sense of smell most highly developed, and hence, even if we did not know that the sense of smell is located in the antenna, it would seem more reasonable to suppose that the glands of the mandibles are connected in some way with the functions of these organs themselves. The mandibles, as already stated. are used for eating pollen and as tools for manipulating and modeling wax. Therefore, according to Arnhart (1906). since the queen does not eat raw pollen, the product if 49 THE ANATOMY OF THE HONEY BEE. of the mandibular glands must be intended for softening the wax when it is worked in the jaws. The secretion of the glands is said to be very volatile and strong smelling and to have an acid reaction. It is probably entirely possible that it may have a solvent effect upon the wax, or even, when mixed with it, change somewhat the chemical composition of this substance; in fact, some investigators claim that the wax of the comb ditfers chemically from that freshly taken from the wax plates. Even this explanation, however, does not seem en- tirely satisfactory, for the only occasions on which the queen has any- thing to do with wax is when she gnaws her way out of her cell after hatching or bites her way into the cells of young queens in order to sting them. However, these occasional uses by the queen of her mandibles appear to be important enough to maintain the large size of these organs in the queen, and it may be reasonable to assume that the demand upon their glands is likewise a large one when it does occur. Yet the mandibles of the queen are toothed and _ sharp pointed, which should provide her with sufficient cutting power both to emerge from her own cell and to enter the cells of other queens, and so, on the whole, the opinion of Schiemenz that the secretion of the mandibular glands is merely sal- vary in function would seem to be Fic. 14.—Internal mandibular gland the simplest explanation and the (2MdGl1) of worker, lying against inner : wall of postgena (P96) and opening 00st. losieal one = ioweveeeas te agh SER eens ee end actual test should certainly be made to determine whether the worker’s manipulation of the wax with her mandibles produces any change in it, and to discover whether the queen simply bites her way mechan- ically through the wall of the cell or at the same time softens the wax by a secretion from her mouth. The male in any case has little use for his mandibles, and the glands are so small that they must certainly be functioniess. A second mandibular gland (fig. 14, 24/dG@7) is present in the worker. It consists of a delicate, flattened, racemose mass lying against the internal face of the wall of the fossa of the proboscis. whose duct opens into the mouth cavity at the posterior inner edge of the mandible. This gland was first described by Bordas (1895) as the internal mandibular glaid. According to him, it corresponds with a similar gland in the Bombidz (bumblebees) and in the Ves- pide (yellow jackets) and to the maxillary glands of other Hy- menoptera. Nothing is known of its secretion. 7 7 THE HEAD OF THE BEE AND ITS APPENDAGES. 43 4. THE PROBOSCIS. The conspicuous group of mouth appendages in the honey bee, forming what is commonly known as the proboscis (fig. 9 A, Prb), is © ” + ! SS — Z SS fier Sas ; . with the maxille and the labium of insects that feed on solid oa ak 44 THE ANATOMY OF THE HONEY BEE. food alone. By separating the parts of the proboscis a little (fig. 9 B) it will be seen that, while there are five terminal pieces present, three of them arise from one median basal sclerite (J/¢), the two wider lateral appendages (J/x) being carried each by a separate lat- eral basal piece (S7). The median group constitutes the dabzwm and the separate lateral parts the maville. If the reader will now turn again to figure 3 C (p. 17), which may represent any generalized insect labium, and compare with it the drawing of the bee labium, forming the median series of parts in fig. 15 D, he will at once be able to identify the parts of the latter. The principal elongate median basal plate is the mentum (J/t), the small triangular plate at its base is the submentum (Smt), and the two jointed lateral appendages of the mentum are the labial palpi (LbPlp), each carried by a basal palpiger (Pilg). It is only the parts of the bee’s labium that le between the palpi which are actually different from those in the generalized diagram where they consist of the four lobes of the ligula (Gls and Pgl). But even here it will be seen that the two small lobes (Pg/) in the bee’s labium, partly con- cealed within the bases of the palpi, correspond with the paraglosse. Hence we have only the long median appendage to account for and it is unquestionably the representative of the glossw (Gls) which are here fused together and drawn out into this flexible tonguelike organ. In fact, a comparison with the mouth parts of other Hymenoptera in which the elements are much less modified leaves no doubt of this being the true interpretation of the bee’s labium. It is simply an example of how nature constantly prefers to modify an already exist- ing part to serve some new purpose rather than to create a new organ. If, then, we bear in mind that the slender median appendage of the bee’s labium represents the gloss of other insects, we may for convenience call it the “tongue,” as it is popularly termed, or, since it is a single organ, there is probably no grammatical objection to calling it the glossa. The word “tongue,” however, to use it prop- erly, should be appled to the true lingua or hypopharyna (fig. 3 C and D, Zphy) which arises from the upper surface of the labium. Many of the older entomologists, adopting the notion from Kirby and Spence, who defined the term in 1826, regarded the glossa of the bee as the homologue of the lingua in other orders. Even Pack- ard in his Text-book of Entomology calls the glossa the “ hypo- pharynx.” Cheshire named it the “ligula,” and his mistake has been perpetuated by several other writers on bee anatomy, including Cook and Cowan. The term /igula properly includes both the glossa and the paraglossee, or should signify the basal piece from which these four lobes arise (fig. 3 C, Zyg), so that it can not be applied to the glossa alone. e 7 - os THE HEAD OF THE BEE AND ITS APPENDAGES., 45 The derivation of anatomical names counts for nothing in their application—this must be determined by scientific usage and priority. Thus, glossa is the Greek word for “ tongue,” but it was first applied in entomology to the median lobes of the labium; Jingua is its equiva- lent in Latin and was first given to the true tongue or hypopharynx in insects; ligula is a diminutive derivative from “ lingua” and has come to be apphed collectively to the terminal parts of the labium beyond the mentum but not including the palpi. Hence, all these words mean the same thing by thei origins, but their anatomical applications should be carefully distinguished. In this paper there- fore the slender median appendage (Gls) of the labium will be called the glossa, or, for convenience, the tongue, but with the strict understanding that the organ in question is not the true tongue. This latter should be called the “ hypopharynx,” but, as will be shown later, it is absent in the bee. The glossa of the bee (figs. 9 B; 11 A and B, and 15 D, F, and G, Gls) is covered with long hairs which increase in length toward the end. The tip is formed of a small spoon-shaped lobe, the /abellum or bouton (Lb/), which is covered by short delicate processes branched at their ends (fig. 15 A and B, Zd/). The long hairs of the glossa are arranged in circles and the transverse rows of hair bases give the tongue a multiarticulate appearance. Surrounding the dorsal side of the base of the labella and forming two short subterminal rows on the ventral side of the glossa are a number of stiff, out- wardly curved, spinelike hairs (#7). These hairs have been de- scribed as taste organs, but their appearance would suggest that they are simply protective spines guarding the delicate tip of the tongue. Between the two ventral rows of these spines is the termination of a groove (A, %) which extends along the midline of the under sur- face of the glossa (D, /) to its base (fig. 9 B,%). The cleft of this eroove is covered by two fringes of converging hairs whose ttps are inclined also toward the tip of the tongue. Let us now return to a study of figure 15 D. The series of lateral pieces as already explained are the maxille. A comparison with figure 3 B representing a generalized maxilla will show that these organs in the bee have suffered a greater modification than has the labium, but the parts can yet be quite easily made out. The main basal plate (St) is the combined stipes, subgalea, and palpifer, the basal stalk is the cardo (Cd), and the httle peglike process (J/vPlp) at the outer end of the stipes is the greatly reduced maxillary palpus. Hence, we have left only the terminal bladelike lobe (J/a) to account for, and it is evident that it must be either the galea or the lacinia (see fig. 3 B, Ga and Zc) or these two lobes combined. Here again a comparative knowledge of the mouth parts of Hymenoptera comes AG THE ANATOMY OF THE HONEY BEE. to our aid and shows clearly that the part in question is the outer — lobe or galea, for the inner one becomes smaller and smaller in the higher members of the order and finally disappears. The base of the submentum is connected in the bee with the upper ends of the cardines by a flexible, widely V-shaped band, the Jorwm (Lr). The posterior angle of the submentum rests in the apex of the lorum, while the tips of the loral arms are movably articulated with the distal ends of the cardines. The name “lora” was given to this structure by Kirby and Spence, but “lorum” is more correct, since this is the Latin form of the word (meaning a thong or lash). Some recent entomologists have spoken of the structure as consisting of two rods, thus making the word do duty as a plural, but the thing itself is all one piece. Cheshire and some others have incorrectly applied the name to the submentum. The lorum is peculiar to the Hymenoptera, and the reason for it is clear when we examine the attachments of the parts of the proboscis to the head. As already stated, the maxille and labium are sus- pended in a large cavity on the back of the head which may be called the fossa of the proboscis (fig. 9 B, PrbF’s). The maxille are articu- lated by their cardines (Cd) to the maxillary suspensoria (fig. 11 A, e) at the upper edges of the side walls of the fossa. The labium, on the other hand, is not attached to the solid walls of the cranium but is suspended in the membranous floor of the fossa. This is to afford it freedom of movement during feeding, but, in order to give it more substantial support and to make the regulation of its motions possible, the submentum is slung to the ends of the cardines by the lorum. The terminal lobes of the labium and mawille when not in use are ordinarily folded down beneath the head against the mentum and stipites (fig. 19). When, however, the bee wishes to imbibe a thick liquid such as honey or sirup in large quantity, these parts are straightened out and held close together so as to form a tube between them leading into the mouth, the terminal joints of the labial palpi alone diverging from the rest (fig. 11 A). The action of the mouth parts while feeding may be observed quite easily if some bees are given a small amount of honey and then watched through a lens while they are eating. A most convenient method is to put a few workers in a small screen-covered cage, such as are used for queen nurseries, spread a small drop of honey on the wire, and then place the cage under a simple microscope. It will be seen that the maxille are held almost stationary but that the base of the labium slides back and forth between the maxillary bases with a very regular to-and-fro movement as if the honey were being either pumped or sucked up into the mouth. It is probable that there is a sucking force exerted by the pharynx (fig. 11 B, Phy) but not THE HEAD OF THE BEE AND ITS APPENDAGES. 47 by the honey stomach (fig. 44, MS), which latter, as Cheshire re- marks, could no more suck honey through the cesophagus than a balloon could suck gas from a pipe. The liquid undoubtedly runs up the temporary tube between the blades of the mouth parts first by capillary attraction, but it must be greatly assisted along its way to the mouth by the retraction of the labium. The load brought up when this is pulled back is then sucked into the mouth by the pharynx while the labium immediately goes out again after more. It acts thus as a sort of mechanical feeder and this function is prob- ably derived from the lapping motion of the under lip in wasps and hornets. The mentum (fig. 15 D and G, J/t) is hinged freely upon the submentum (Smt), the latter, as already described, is set into the socketlike angle of the lorum, while, finally, the arms of the lorum are articulated to the distal ends of the cardines of the maxille. Now, when the labium is retracted by means of muscles attached to the mentum, the submentum turns in the loral socket and assumes a position at right angles to the mentum while the lorum itself turns somewhat on its articulations with the cardines. This great freedom of motion is permitted by the loose membrane of the fossa in which both the maxille and the labium are suspended. The observer, however, can not fail to note that beside this motion of the entire labium the tongue itself, or glossa (@/s), performs a conspicuous independent movement of its own. It is by far the most active member of the mouth parts during feeding, being actively thrust out and retracted while its tip is constantly moved about in a way suggestive of its being delicately perceptive of taste or touch or perhaps to both of these senses. So great is the retractile power of the tongue that its tip, which normally extends far beyond the end segments of the labial palpi, can be drawn back entirely within the latter. This contractile activity appears at first sight to be due to elasticity, but a closer examination will show that the entire ligula, 1. e., the paraglosse (Pg/) as well as the glossa (Gls), moves back and forth and that the action is due to a retraction of the base of the heula (fig. 15 F, Zg) into the anterior end of the mentum (.J/?). The ligula is supported on a membranous cone at the end of the mentum whose walls are strengthened by three thin chitinous plates, two above (F,°p) and one below (D, 0). By the contraction of muscles situated within the mentum (fig. 16, 7?J/c7) and inserted upon the base of the ligula the latter is pulled into the end of this cone whose walls, including the chitinous plates, simply turn inward. But the tongue does possess also a contractile power of its own by means of which it actually shortens its length. A flexible rod arising from the median ventral supporting plate (fig. 15 D, 0) of the ligula extends throughout its length. The base of this rod is curved down- AS THE ANATOMY OF THE HONEY BEE. ward and has two muscles attached to it. This is shown by figure 15 H, where the rod (7) is torn from the glossa (@/s) basally so as to show the muscles (2f.i/c/) inserted upon it and its connection with the plate (0). By the contraction of the muscles the rod bends at its base and is drawn back into the mentum. The glossa thus shortens and becomes bushy just as does a squirrel’s tail when one attempts to pull the bone out of its base. The protrusion of the parts is due to the pressure of blood driven into the ligula from the mentum, while probably the glossa extends also by the straightening of its rod as the muscles relax. Wolff described a protractor muscle at the base of the ligula. The rod of the tongue is certainly not in itself contractile, as supposed by Cheshire, who looked for evidence of muscular striation in it. It has mostly a transparent and cartilaginous appearance, but is presumably chitinous. The mouth parts, their action in feeding, and the muscular mech- anism by which they are moved have been elaborately described and illustrated by Wolff (1875) in his monograph on the organs of smell in bees. Most unfortunately, however, Wolff’s paper was written to show that the seat of the sense of smell is in the mouth, a most erroneous notion, and the title of his paper based on this notion has caused little attention to be paid to this work on the mouth parts of the bee, which is one of the best anatomical treatises ever produced on the mouth parts of any insect. It still remains for us to describe the details of the glossa and its particular function in feeding. The tongue is not a solid appendage nor yet is it truly tubular. A compromise is effected by the longi- tudinal groove (fig. 15 A and D, 7) on its ventral surface which expands within the tongue into a large cavity occupying half of its interior (E, Zum). The glossal rod (7), which has already been mentioned, lies in the dorsal wall of this channel and is, hence, really not an internal but an external structure. The rod is itself erooved along its entire ventral length (E, 7) and this eroove again is converted into a tube by two rows of short hairs which converge from its margins. The lips of the ventral groove of the glossa are so deeply infolded that its cavity is almost divided along the midline. Hence, the glossa might be described as containing three channels— a small median dorsal one (27) and two large latero-ventral ones (Lum). The glossal rod (fig. 15 C, 7) is very flexible but not contractile, as already stated, and is mostly clear and cartilaginous in appearance, its ventral groove (7) alone being lined by a deposit of dark chitin (fig. 15 C and E). Its shape in section is sufficiently shown by the figures. The walls of the large channels of the proboscis consist of | a delicate membrane (C and E, g) covered with very small hairs. — * 2 s Pte THE HEAD OF THE BEE AND ITS APPENDAGES. 49 The entire ventral cavity (Lum) with the rod (7) can be evaginated through the ventral cleft (4) by blood pressure from within. As Cheshire points out, this permits of the channels being cleaned in case of clogging by pollen or any foreign matter. It is supposed that these glossal tubes are of especial service to ihe bee by enabling it to take up the smallest drops of nectar—-quantities that would be lost in the clumsy tube formed between the parts of the jabium and the maxille. The suction must be in large part A o capillary attraction, but here again the shortening of the glossa by the retraction of its rod must squeeze the contained nectar out of the upper ends of the channels where it is received upon the ventral flaps of the paraglosse (fig. 15 F, Pgl), from which it runs around the _base of the tongue (Gls) within the paraglosse to the dorsal side of the mentum (J/t) and so on to the mouth. - The maxille and labium of both the queen and the drone (fig. 11 B) are smaller and weaker than those of the worker, and neither of these two forms is capable of feeding itself to any extent. Ifa hungry queen be given some honey she attempts to eat it and does imbibe a small quantity, but at the same time = gets it very much smeared over her head and thorax. The mouth is hard to define in insects; practically it is the space surrounded by the bases of the mouth parts, but strictly speaking it is the anterior opening of the alimentary canal situated behind the bases of the mouth parts (fig. 19, 17th). Yet the enlargement of the alimentary canal (Phy) immediately following this opening is never spoken of as the mouth cavity but is called the pharynx. On the © other hand the so-called epipharynx (phy) and hypopharynx (absent in the bee) are located in front of this opening and are con- sequently not in the pharynx at all, the former being attached to the under surface of the labrum and clypeus, while the latter is situated on the upper surface of the base of the labium. These and numerous other inconsistencies in the nomenclature of insect morphology have to be endured because the parts were originally named for descrip- tive purposes by entomologists who were not familiar with scientific anatomy. In this paper the term mouth will be applied to the true oral opening (fig. 19, J/th). The space in front of it between the bases of the mouth parts may be called the preoral cavity. The duct of the salivary glands of insects in general opens upon the base of the labium in front of the hypopharynx. In the honey bee the salivary opening is on the dorsal side of the base of the ligula between the paraglosse (fig. 15 F, SalDO). This alone would show that the glossa is not the hypopharynx of the bee, as many authors have supposed, for otherwise the opening of the salivary duct should be ventrad to the base of the glossa. Im fact, this makes it clear that ootee No. 1810-4 50 THE ANATOMY OF THE HONEY BEE. the bee does not possess a hypopharynx. There is, however, a con- spicuous chitinous plate located on the anterior part of the floor of the pharynx (fig. 19, s) having two terminal points hanging downward over the lower lip of the oral aperture, but, although this plate is truly hypopharyngeal in position, it is not the homologue of the organ called the hypopharynx in other insects. It is variously developed in all. Hymenoptera, being simply a chitinization of the floor of the pharynx, and should be called the pharyngeal plate (Schlundbein of Wolff). It will be more fully described in connection with the ali- mentary canal. Ifa hypopharynx were present it should be situated on the upper side of the labium (see fig. 3 D, Hphy) but there is here present only a plain arched membranous surface in the honey bee and other typical Hymenoptera. The external location of the salivary opening enables the caligd to be mixed with the food before the latter enters the mouth. This is necessary in insects since the Jaws are also on the outside of the SalDO Fic. 16.—Median section through distal half of mentum (Mt) and base of ligula (Lg) of worker, showing opening of salivary duct (SalDO), and muscles connected with ligula and the “salivary syringe’”’ (@). mouth, and whatever chewing or crushing the food receives from them is consequently done in the preoral cavity. In some insects the saliva is used for other purposes than diges- tion. For example, the saliva of some predaceous insects with piere- ing mouth parts belonging to the order Hemiptera is poisonous, and when one of these insects “ bites,’ the saliva is injected into the wound by a special pump. The bite of the mosquito is made painful likewise by an irritant secretion from a part of the salivary glands. Bees appear to have the power of letting their saliva run down the tongue when necessary to dissolve a hard substance like sugar and render it capable of being taken up in solution, for they do not eat sugar with their mandibles. Moreover, there is even a sort of pump or so-called “salivary syringe” at the termination of the salivary duct in the ligula, by means of which the secretion can be forcibly ejected from the opening. The salivary opening on the base of the ligula (fig. 15 F, SalDO) leads into a deep transverse pit with collapsible cartilage-lke walls having its deepest part turned horizontally toward the base of the P- a THE HEAD OF THE BEE AND ITS APPENDAGES. 5 labium (fig. 16, ¢). The salivary duct (Sal?) bends downward in the anterior part of the mentum (J/¢) and opens into the posterior end of the pit (¢). When the retractor muscles (1?J/cl) of the ligula pull the latter back into the mentum the lps of the salivary pit must necessarily be closed. The simultaneous contraction of the elevator muscle (w) attached to the roof of the horizontal part of the pit must expand the latter and suck the saliva from the salivary duct. When, finally, these muscles relax and the hgula is driven out by blood pressure in the mentum, probably produced in part by the contraction of its dorsal transverse muscles (7J/cl), the saliva in the temporarily formed bulb must be squirted out upon the base of the tongue. Wolff (1875) calls each dorsal longitudinal muscle of the mentum (//J/cl)—the two inserted upon the basal hooks (7) of the glossa (fig. 15 H and fig. 16)—the retractor lingue longus. The large ventral retractor muscle of each side (2RJ/cl) he ealls the retractor lingue biceps since its anterior end divides into two parts, one of which is inserted by a tendonous prolongation upon the base of the glossal rod (fig. 15 H and fig. 16, 7) and the other upon the base of the hgula. The use of the word “ lingua” in these names is objectionable because, as already explained (page 45), the lingua is properly the true tongue or hypopharynx. “ Ligule ” should be sub- stituted for “ lingue.” The dilator muscle (fig. 16, w) of the salivary pit (¢) is termed the protractor lingue by Wolff because, as he sup- poses, when the ligula is pulled back into the mentum the position of this muscle is reversed, so that a contraction of its fibers would help to evert the ligula. The glands that furnish the saliva he within the head and the thorax and will be described later in connection with the alimentary canal and the process of digestion. Fic. 17.—Epipharynx (Ephy) and labrum (im) of worker: A, ventral view; B, anterior view. 5. THE EPIPHARYNX. The epipharynx of insects in general may be described as a dorsal tongue, it being a median Jobe developed on the roof of the preoral cavity from the under surface of the clypeus or labrum and situated opposite the hypopharynx. 59 THE ANATOMY OF THE HONEY BEE, The epipharynx of the bee is a large three-lobed appendage de- pending from the roof of the preoral cavity just in front of the mouth (fig. 19, Bphy). Seen from below it is triangular (fig. 17 A) with the apex forward. Its median lobe has the form of a i < with a pit in the summit bearing a small hair (fig. 18). These are regarded as organs of taste. Wolff (1875) made a most thorough study of the epipharynx, which he called the “ palate sail” (Gauwmensegel) on account of the high median crest. His drawing is the standard illustration of the organ found in nearly all books on the anatomy of the honey bee & a-m zs ? . Ng Gls hi : it ~~ \ ie AAT pf \ - LbPlo Fic. 19.—Median longitudinal section of head of worker, but with entire labium attached, showing internal organs except muscles and brain. and in most works on general insect anatomy and the sense organs. Wolff, however, regarded the sensory cones as having an olfactory function, and this led him to erroneous conclusions regarding the functions of several other organs. For .example, he thought that the mandibular glands poured a liquid upon the surface of the THE THORAX AND ITS APPENDAGES. 58 epipharynx which kept it moist and capable of absorbing odor particles, while he ex- plained the inhalation of the latter into the preoral cavity as brought about through the contraction of the air sacs situated about the .mouth. Wolff's anatomical researches are without doubt some of the best ever made on the bee, and it is due to his mis- taken idea of the loca- tion of the sense of smell, which, as al- ready explained, is on the antenne, that we have received from him a most excellent account and detailed drawings not only of the epipharynx but of the mandibular glands, the mouth parts, the salivary “ pump,” and the respiratory organs. IV. THE THORAX AND ITS APPENDAGES. 1. THE STRUCTURE OF THE THORAX. The apparent thorax of the bee (fig. 20, Y,-IT, and fig. 21) and of most other Hymenoptera is not exactly the equivalent of the thorax in other insects. The middle division of the body, SO conspicuous in this LATE HUA ¥ Iw We = EE 4 IS 20.—Dorsal view of ventral walls and internal skele- ton of body of worker. order, consists not only of the three leg-bearing segments, which alone 54 THE ANATOMY OF THE HONEY BEE. constitute the thorax of all other insects, but also of the first ab- dominal segment. The conspicuous necklike constriction posterior to the base of the hind legs (fig. 21, Pd) is, therefore, between the first and the second abdominal segments (fig. 1, 77 and J/7'). The thorax of the honey bee at first sight looks entirely different in structure from that of all other insects except related Hymenoptera, in the higher families of which group it is more highly modified than in any other order of the whole series of insects. When, however, we examine the thorax of one of the lowest members of the Hymenop- tera, such as a sawfly, we are surprised to find that, in each segment, the structure agrees very closely with our ideal diagram of a general- ized thoracic segment (fig. 4). The three seg- ments are per- fectly distinct, and the first abdominal seg- ment, while it may be clearly separated from the rest of the abdomen, is not fused into the thorax so as to appear to be a part of 1. now, we exam- ine representa- tives of several Fic. 21.—Thorax of worker, left side, with intersegmental lines ae 2 somewhat exaggerated, showing prothorax (Ti, Eps, C21), families inter- mesothorax (Ts, Epse, Epm2, Ss, C#2), metathorax (T3, Pls, mediate between plz, Cz#;) and propodeum or first abdominal segment (JT). 2 the sawflies and the bees, the line of specialization that has produced the bee thorax becomes perfectly evident. The principal features in these modifi- cations are the following: (1) The lateral and ventral parts of the prothorax (figs. 20 and 21, Eps, and S,) are suspended loosely in a large membranous area which is continuous anteriorly as the neck. They thus form a sort of suspensorium for the front legs, which appears detached from the rest of the thorax. (2) The protergum (77) is solidly attached to the anterior edge of the mesothorax and its lateral parts extend downward till they meet on the venter behind the prosternum (figs. 20 and 21). (3) The postnotum (postscutellum) of the mesothorax (figs. 22, PN; 23 A, PN.) is entirely invaginated into the cavity of the thorax and is reduced to the form of two lateral arms of the large THE THORAX AND ITS APPENDAGES. 55 internal pos.phragma (Pph) which has no median tergal connection at all. (4) The metatergum (figs. 21 and 23 A, 7.) consists of a single narrow plate. (5) The metapleurum (fig. 21, Pl, and -pl,) shows no trace of a division into episternum and epimerum, but is divided into an upper (/7/,) and a lower (pl,) pleural plate. (6) The first abdominal tergum (fig. 21, 77’) is solidly attached to the metathorax and forms an intimate part of the thoracic mass. We shall now proceed with a more detailed account of the thorax. and the reader should occasionally turn back to figure 4 (p. 19) in order to keep clearly in mind the parts that make up a generalized thoracic segment. The parts of the prothorax are so separated from each other that they appear to belong to different segments. The protergum (fig. 21, 7,) forms a collar completely encircling the front of the mesothorax. On each side a large lobe (w) projects posteriorly as far as the base of the front wing and constitutes a protective shield over the first thoracic spiracle. The tergum presents a median transverse groove, dividing it into an anterior and a posterior part, which parts may be called the scutum (fig. 23 A, 7,, Sct) and scutellum (Scl). The propleurum (figs. 20, 21, H'ps,) consists of a large plate presenting both a lateral surface (fig. 21) and a ventral surface (fig. 20). On account of the position of the coxal articulation (fig. 21) this plate would seem to be the anterior pleural plate alone (see fig. 4), which is the episternum. In some Hymenoptera the epimerum is repre- sented by a very small plate on the rear edge of the episternum. The anterior ends of the two episterna form knobs which loosely articulate with the occipital region of the head (figs. 11 B, 20, and 21). lying just ventrad of each is a slender cervical sclerite (fig. 21, mi). The prosternum (S,) is shown by figure 20. It carries a large entosternum (/’~,), forming a bridge over the nervous system behind the prothoracic ganglion (fig. 52). The mesotergum, as seen in its natural position (fig. 21, 7’,), consists of a large anterior scutum (Sc¢,) and of a smaller but very prominent posterior scutellum (Scl,), separated by a very distinct suture (wv). The scutellum has two latero-anterior areas partially separated from the median area by sutures. When the mesotergum is detached from the rest of the thorax (fig. 22) it is discovered that there is attached laterally to the scutellum a large posterior internal part, which does not show on the surface at all. This is the representative of the postscutellum (Pscl) and its phragma (Pp/) constituting the post- notum (PV) of our diagrammatic segment (fig. 4). The proof of this, again, is to be derived from a study of the lower Hymenopteran families. In some of the horntails (Siricide) the postnotum or postscutellum is a prominent plate on the surface of the dorsum be- hind the seutellum. In Sivex (Siricide) this plate is sunken below 56 THE ANATOMY OF THE HONEY BEE. the general surface and mostly concealed between the mesothorax and the metathorax. In higher families such as the Pompilidez the postnotum of the mesotergum is entirely concealed by invaginaticn, but it still carries a very large phragma. When, now, we come to the highest members of the order we find that the median part of the postnotum in the mesothorax is gone entirely and that it is repre- sented only by the lateral arms (figs. 22, PV; 23 A, PN.) carrying the large, purely internal postphragma (Pph). 7 The mesopleurum is large and consists principally of the episternum (fig. 21, Hps,), which, however, is continuously fused with the meso- sternum (figs. 20 and 21, S,). The pleural suture (fig. 21, PS.) is short and sinuous and does not reach more than half way from the wing process to the base of the middle leg. The epimerum is reduced to a small double plate lying above the episternum and posterior to the wing process (figs. 21, Hpm., and 24 A, Xpm and Hpm). The pleural ridge (fig. 24 B, PR) is weak, but the wing process (WP) is well braced by a num- ber of accessory internal ridges. One preparapterum (2P) and one postparapterum (3P) are present. Lying behind the postparapterum is another larger sclerite (fig. 24 A and B, pn), whose anterior end is Fic. 22.—Lateral view of mesotergum of worker, removed from the rest cf thorax to show large internal postscutellum (post- notum, PN) and its phragma (Pph) not visible normally in the bee from exterior. articulated to the edge of the epimerum and whose posterior tapering end is loosely asso- ciated with the terminal arms of the postnotum (fig. 22, PV and pn). This sclerite might be regarded as the fourth parapterum, but it is much more probably the representative of a small terminal bar of the postnotum present in other Hymenoptera, such as Pepsis, which connects this tergal plate with the epimerum, though in this genus it is not detached from the main postnotal sclerite. Both the mesosternum (fig. 20, S,) and the metasternum (S.) con- tribute to the formation of a large entosternum (/'v,..), which forms a protecting bridge over the combined mesothoracic and metathoracic | ganglia (fig. 52) and affords attachment for the ventral longitudinal muscles of the thorax (fig. 27, /mc/). The metathorax consists of a very narrow series of plates (fig. 21, T,, Pl,, and pl,) compressed between the mesothorax and the first abdominal tergum (J7). Its back plate is a single, narrow, transverse sclerite (figs. 21 and 23A, 7,) widening on the sides, where it carries the wings by the two wing processes (fig. 23 A, dVP and PVP). The THE THORAX AND ITS APPENDAGES. 57 ordinary tergal divisions seem to be entirely obliterated. The meta- pleurum consists of a dorsal plate (fig. 21, P/,) supporting the hind wing and of a ventral plate (p/,) carrying the hind leg. These two functions certainly identify these two plates as constituting together the metapleurum, but there 1s absoluteiy no trace of a division into an episternum and.an epimerum. Once more, therefore, we have to go back to the generalized Hymenoptera to find out what has happened. Sct Ne iy IT Nyy: ee | ill) Hy | HF H Bai \ il| é \\\ . i\ i \\\ 1h \) , \ \ 4 MiLp 7 Fig. 23.—A, thoracic terga of worker separated from one another, showing protergum (T,), mesotergum (7';) and its internal postscutellum (postnotum PNs) and phragma (Pphe), metatergum (Ts) and propodeum or first abdominal tergum (J7); B, ventral view of principal or notal plate of mesotergum. The answer is simple. Sirexv has a typical metapleurum consisting of an episternum and epimerum separated by a complete pleural suture. In the higher forms this suture simply disappears, and consequently the pleurum shows no traces of its original component plates. The division into a wing-bearing and a leg-bearing plate is, therefore, a purely secondary one. None of the Hymenoptera has separate trochantinal sclerites (see fig. 4, 77), but, since the coxe are articulated ventrally to knobs 58 THE ANATOMY OF THE HONEY BER. (figs. 20 and 21, 2) apparently belonging to the sterna, it might be supposed that the trochantins have fused with the latter plates. The posterior part of the thoracic mass (fig. 21) consists of the first abdominal tergum (/7’), which fits into the deeply concave pos- terior edges of the metathorax and forms the peduncle (Pd) that carries the rest of the abdomen (fig. 32). It consists of a single large, strongly convex sclerite (figs. 21 and 23 A, 77) bearing the first abdominal spiracles laterally (JSp) and having its surface divided into several areas by incomplete sutures. . Many entomologists find it difficult to believe that this plate, which so apparently belongs to the thorax, is really derived from the abdo- men. But the proof is forthcoming from a number of sources. In the first place, the thorax is complete without-it and the abdomen is incomplete without it, the latter having otherwise only nine seg- ments. Again, if the plate is reckoned as a part of the thorax we WP, oP / => 3P -2P Za al tes je Epm 4 \) eon . Wy pm \) \\ Ny iy = = 1 y => ==} = Eps e — ia Fig. 24.—A, upper part of left mesopleurum of worker, external; B, inner view of same. should have the anomaly of a thorax with three pairs of spiracles— there being the normal two on each side situated, as they always are, between the true thoracic segments. Furthermore, comparative anat- omy shows us that in some of the sawflies (Tenthredinide) the first abdominal tergum, while separated by a wide membranous space from the second, is not at all incorporated into the thorax. In a horn- tail such as Sivex (Siricide) the entire first abdominal segment is fused to the posterior edge of the metathorax and is only loosely joined to the next abdominal segment by membrane. This insect affords, therefore, a most complete demonstration of the transference of this segment from the rest of the abdomen to the thorax. Finally, we have absolute proof of its abdominal origin based on a knowledge of development, for it has been shown by Packard from a study of the bumblebee that the first abdominal segment of the larva is trans- ferred during the pupal metamorphosis to the thorax and forms the ak ; THE THORAX AND ITS APPENDAGES. 59 part under discussion. We hence see that not only the first abdom1- nal tergum but the entire segment has undergone transposition, though the ventral part has disappeared in all the higher families. This transferred part has been named both the median segment and the propodeum by writers who recognize it as belonging to the abdo- men and not to the thorax. The names current among systematists for the back plates of Hymenoptera afford an excellent example of the errors that ento- mologists may be led into through an ignorance of the comparative anatomy of insects. They recognize the protergum as such and then, knowing that there are yet two segments to be accounted for, they call the mesoscutum the “mesonotum,”’ the mesoscutellum the “scutellum,” the metatergum the “ postscutellum” (being unaware that the true postscutellum is deeply concealed within the thorax), while the first abdominal tergum is called the metathorax. Such a nomenclature assigns both pairs of wings to the mesothorax. Too many systematists working in only one order of insects do not care whether their names are applied with anatomical consistency or not. 2. THE WINGS AND THEIR ARTICULATION. in the study of insects the wings always form a most interesting subject because by them insects are endowed with that most coveted function—the power of flight. It has already been stated that the wings are not primary embryonic appendages, but are secondary out- erowths of the body wall from the second and third thoracic seg- ments. Therefore it is most probable that the early progenitors of insects were wingless, yet for millions of years back in geological time they have possessed these organs in a pretty well developed condition. Nearly all of the insect orders have some characteristic modifica- tion of the wing-veins and their branches. None of them, however, departs nearly so far from the normal type as do the Hymenoptera, even the lowest members of this group possessing a highly specialized venation. Before beginning a study of the Hymenopteran series which leads up to the bee the student should first turn back to figure 6 (p. 22) and again familiarize himself with the generalized condi- tion of the veins and the articular elements of the wing. By com- paring, now, with this diagram the basal parts of the wing of a sawfly (ltycorsia discolor, fig. 26 A) it will be easy to identify the parts of the latter. Vein @ has two little nodules (C, C) cut off from its basal end which lie free in the axillary membrane. Vein Se articu- lates by an enlarged and contorted base (Sc) with the first axillary (1A), while vein 7 is continuous with the second (2A). The next two veins that come to the base and unite with each other are appar- ently not the media and cubitus but the first and third anals (7A and 60 THE ANATOMY OF THE HONEY BEE. 3A), since they are associated with the third axillary (34z). In this species the subcosta (Sc) is entirely normal, but in the related horntail (Sirex flavicornis, fig. 26 B) the enlarged basal part of the subcosta is almost separated from the shaft of the vein, while the latter (fig. 25.A, Se) is short and weak. ~ oo o— Ss —_ Co a. te o> ies os AntL - WY HW -AntNv 2Br FtCom SceGne¢ ~~ Fig. 53.—Brain and subcsophageal ganglion of worker and their principal nerves, anterior view. The subcesophageal ganglion consists of at most four ganglia which innervate the mandibles, the hypopharynx, the first maxille, and the labium or second maxille. In adult insects the body ganglia also very commonly fuse with one another in varying combinations, for the number present is always less than the number of segments, vary- ing from eleven to one. The brain of the bee (fig. 53, Br) is distinctly composed of two parts, the protocerebrum (/&7), carrying the large optic lobes (OpL), and the deutocerebrum (287), which consists principally of the con- 126 THE ANATOMY OF THE HONEY BEE. spicuous antennal lobes (AntZ) that give off the large antennal nerves (AntNv). The tritocerebrum is not present as a distinct brain division, and its nerves, the labral (Zmv) and the frontal (FtCom), appear to arise from the deutocerebrum at the base of the antennal lobes. The frontal ganglion (/t@ng), formed at the union of the two frontal nerves, gives off a very small, anterior, median nerve and a much larger, posterior, stomatogastric trunk (StgNVv, represented in the drawing as cut off a short distance behind the frontal ganglion) which goes backward on the dorsal side of the pharynx beneath the brain. Behind the latter, and just where the pharynx contracts to the tubular cesophagus, the stomatogastric nerve bears a pair of small ganglia which are connected by short nerves with the brain, and then it breaks up into branches that go posteriorly along the cesopha- gus but have not been traced. The circumcesophageal commissures are so short in the bee that the subcesophageal ganglion appears to be attached directly to the lower ends of the brain, while the cesophagus appears to penetrate the latter between the antennal lobes. The three principal pairs of nerves from the lower ganglion (J/dNv, MaNv, and LbNv) go to the mouth parts. A most thorough study of the internal structure of the brain of the bee has been made by Kenyon (1896), to whose paper the reader is referred if interested in this subject. Kenyon’s descriptions have never been verified, but his work has an appearance of thoroughness and carefulness. He applies the term “ brain” to both of the nerve masses of the head, distinguishing the upper as the “ dorsocerebrum ” and the lower as the “ ventrocerebrum,” being led to do this from physiological considerations, the separation of the two being merely incidental to the passage of the cesophagus. In the thorax of the bee (figs. 1 and 52) there are two large ganglia (1Gng and 2G@nqg). The first is prothoracic, being situated above the prosternum, in front of the entosternum (fig. 52, /w,), and it innervates the prothorax and the first pair of legs. The second, which is situated in front of the middle legs and is protected above by the arch of the common entosternum of the mesothorax and meta- thorax (fig. 52, #23), is a combination of the mesothoracic and metathoracic ganglia and the first two abdominal gangha. This composite structure is evident from the fact that it innervates both the middle and the hind legs, the bases of both pairs of wings, the mesothorax, the metathorax, the propodeum, and the first abdominal segment behind the constriction (the true second segment). The first and second ganglia of the abdomen (fig. 52, 3@ng and 4G@nq) lie in the first two segments (/7 and ///) behind the constriction, which are the true second and third segments. But since the nerve trunks of these ganglia go, in each case, to the segments behind them, we THE NERVOUS SYSTEM AND THE EYES. roy assume that they really belong to these latter segments, that is, to segments J/7 and JV. The next three ganglia (5@ng, 6@ng, and 7Gng) lie in the segments they innervate (V, VZ, and VZZ) and, hence, belong to the fifth, sixth, and seventh abdominal segments. The last, that is, the seventh ganglion, supphes all of the segments behind it with nerves and is therefore probably a compound of the ganglia originally belonging to the seventh, eighth, ninth, and tenth segments. In connection with the nervous system it is most convenient to give a description of the simple and compound eyes. The other Fig. 54.—Horizontal section of compound eye and optic lobe of worker (after Phillips) : BM, basement membrane; Cor, cornea; fm, fms, fms, outer, middle, and inner fibrillar bodies of optic lobe; inner ch, inner chiasma; Om, ommatidium; OpL, optic lobe; outer ch, outer chiasma. sense organs will be found already described along with the parts on which they are located (see pp. 36 and 52). All the sense organs, to be sure, are of ectodermal formation and are only secondarily connected with the nervous system, but the eyes are so intimately associated with the optic lobes of the brain that their description here seems most appropriate. _ The compound eye of the bee (figs. 9 A, 10, 52, and 53, #) has been specially studied by Phillips (1905) and figures 54 and 55 are re- 4 = produced from his drawings, while the following statements are based on his paper: The convex outer surface or cornea of the eye § Ey 128 THE ANATOMY OF THE HONEY BEE. presents a honeycomb appearance under the microscope, and each httle hexagonal facet is the outer end of an eye tube called an omma- > , * ee, . " AALS AL EATS WADRARUS SNS E7175 7, SEEN OP cy aH ae |.ret.n. Hic. 55.—Histologicai details of compound eye of worker (after Phillips): A, entire ommatidium (somewhat diagrammatic), adult; B, entire ommatidium, as if dissected out, without outer pigment cells (diagrammatic), adult; C, section of entire om- matidium, showing distribution of pigment, adult; D, cross section just proximal to lens, slightly oblique; E, cross section through extreme distal ends of retinule and proximal ends of cones, siightly oblique; F, cross section through retinule, showing relation of outer pigment cells in this region; G, cross section through retinule in region of nuclei; H, cross section through retinule in region of proximal nucleus; I, cross section of eye, cutting basement membrane parallel (the distinctness of nerve fibers of each ommatidium is shown) ; BM, basement membrane; CC, crystalline cone ; CL, crystalline lens ; ¢.-p.c., corneal pigment cell; h.c., hair-cell; l.vet.n., lower retinular nucleus; n.f., nerve fiber; Nv, nerve; o.-p.c., outer pigment cell; ret, retinula; ret.n., retinular nucleus; rhb, rhabdome. tidium, all of which converge toward the internal base of the eye, since each is vertical to the outer surface. Figure 54 is a horizontal THE NERVOUS SYSTEM AND THE EYES. 129 section through the eye and the optic lobe of the brain. The omma- tidia (Om) are seen converging upon the basement membrane (BIL) which is penetrated by the nerve fibers from the optic lobe (OpL). The outer ends of the ommatidia are transparent, forming the facets which together constitute the cornea (Cor) of the eye. The nerve fibers, by a complicated course through the optic lobe, reach the nerve cells of the brain, which are the true seat of sight percep- tion, as of all other sensations, whether conscious or otherwise. The ommatidia (Om), or eye tubes, are separated from one an- other by cells containing a dark coloring matter and known as the pigment cells. Each tube (fig. 55 A) consists of several parts, as fol- lows: First, on the outside, is a clear six-sided, prismatic structure, with convex outer and inner surfaces,.called the crystalline lens (CL), and which forms one of the facets of the cornea. Beneath the lens is a crystalline cone (CC) having its apex directed inward and followed by a crystalline rod or rhabdome (rhb) which extends to the basement membrane (/J/) through the middle of the omma- tidium. (The rhabdome is represented black for the sake of distinct- hess in figure 55 A; its natural appearance is more as shown in B and C.) Surrounding the rod is a circle of eight or nine long re- tinule cells (ret), each containing a conspicuous nucleus (vet. 7) above its middle and continuing basally into an optic nerve fiber (Vv) penetrating the basement membrane. The arrangement of these cells about the rhabdome is shown in cross section at F and G. The inverted apex of the crystalline cone (A, B, and C, CC) is sur- rounded by the corneal pigment cells (c.-p.c.), while the entire omma- tidium below the lens—the base of the cone, the corneal pigment cells, and the retinule—is surrounded by the long outer pigment cells (0.-p. c.), forming a packing between all the ommatidia, as shown in cross section at E. The entire compound eye is simply a modified part of the epidermis (so-called “ hypodermis” of insect histologists) in which the cuticle is transformed into the lenses or cornea, the cones, and the rods, the epithelium into the pigment and retinule cells, and the basement membrane into the floor of the eye perforated by the optic nerve fibers. According to Phillips the ommatidia arise from the ectoderm of the bee larva as groups of epithelial cells which become arranged in the form of spindles surrounded by smaller cells. The cells of the spindles become the retinule, while the surrounding small cells become the pigment cells and the cone cells. The cone cells come to occupy a position external to the retinule by an invagination of the latter, and, through a transformation of most of their protoplasm into a crystalline substance, they form the crystalline cone of the eventual ommatidium. The approximated edges of the retinule cells are 22181—No. 18—10——9 130 THE ANATOMY OF THE HONEY BEE. transformed into the crystalline rod. ‘The cornea is secreted by the corneal pigment cells, which at first lie distal to the cone, and possibly also by the outer pigment cells. The nerve fibers are formed as differentiated parts of the retinule which penetrate through the base- ment membrane (fig. 54, BJ/) and enter the retinular ganglion be- neath it at the outer end of the optic lobe of the brain. Hence the retinule are simply sense end-organs of the skin comparable at an early stage of their development with other sensory epidermal cells, and we thus see how a simple layer of epithelium may be transformed into such an immensely complex organ as the compound eye. There has always been a great deal of discussion as to how insects see by means of the compound eyes. The weight of opinion now favors the theory that they see a part of the object or field of vision with each ommatidium. But it is most certain that, at best, most insects see very indistinctly, and, in fact, it 1s often questioned whether they really see the shape of objects at all or not. A few of them, however, such as dragonflies, appear to have a very acute vision. In the case of the honey bee there is yet much difference of opinion as to whether the workers discover nectar by the bright color of the flowers (1. e., by the sense of sight) or by the sense of smell. The sense of sight in bees and in insects generally, however, may be found elaborately discussed in many books dealing with the senses of insects. The simple eyes or ocelli (figs. 9 A, 10, 52, and 53, O) are con- structed on quite a different plan from that of the compound eyes, each consisting of a lenshke thickening of the cuticle back of which the epithelial cells are specially elongated, and sensitized by nerve connections. The ocelli of the bee, however, have never been care- fully studied. XI. THE REPRODUCTIVE SYSTEM. The reproductive organs are those that produce the cells from -which new individuals are formed. All animals grow from at least — one cell called the egg and almost all from a combination of the egg — with another cell called a spermatozoon. ‘The uniting of these two cells is called the fertilization of the egg. Ina few animals the two different kinds of reproductive cells are formed in the same individ- © ual, but in most of them, including all insects, the sperm and the eggs - are produced in different individuals—the males and the females. In the honey bee the males are called drones, while the females are called queens or workers, according to their functions in the hive. The queens have the egg-producing organs or ovaries greatly devel-— oped, while these organs are rudimentary in the workers. The single active queen in each hive, therefore, normally produces all the eggs — of the colony, while the work of rearing and providing for the brood — hal THE REPRODUCTIVE SYSTEM. 131 falls to the lot of the workers. Most other female insects lay their eggs at some place where the young will be able to find food when they hatch out, and the mother never in any way feeds or protects her offspring; in most cases she dies before her brood emerges from the eggs. But the wasps and bees are different in that nearly all of them make a nest of some sort for the protection of the young larvee when they hatch, in which also they store up food for them to eat. In many species of wild bees all the work of constructing the nest, laying the eggs, and collecting and storing food for the young devolves upon the single female, as it naturally should, since insects do not ordinarily have servants, and the males of most species are utterly irresponsible in such matters. In some of the higher wasps, such as the hornets and yellow jackets, however, the first females that hatch out as adults in the spring help their mother provide for a still larger family by ‘increasing the size of the house and collecting more provisions. Nature designed them for this purpose, moreover, by making them all sterile, allowing them to retain the maternal instincts, but de- priving them of organs capable of producing offspring of their own. Thus there is here a beginning of that division of labor which reaches its highest development in the honey bee, where one form of the fe- male is specialized entirely to produce the young and the other to rear the brood, keep the home in order, gather the food, and ward off enemies. The differences between the queens and the workers are supposed to result from the different diet on which larvee designed to be queens are brought up, but a more thorough investigation of the food given to the different larve of the brood is yet needed before we can decide on the merits of this explanation. The work of numer- ous investigators seems to have demonstrated conclusively that the drone of the honey bee is always produced from an egg cell alone— that is, from an unfertilized egg—while the queens and workers are produced from fertilized eggs. The production of eggs that develop normally without the addition of the male element is called partheno- genesis. In a number of insects, such as some species of scales, a few beetles, and some of the gall-forming Hymenoptera, there are no males known, although the females are extremely abundant. Such cases are often regarded by entomologists as examples of parthenogenesis, and, if they are such, the result of the development of unfertilized eggs is here the formation of females only. A few other insects, such -as some of the plant lice, produce eggs that develop without fertiliza- tion into females or into both males and females, but such cases nearly always occur in a cycle of alternating generations in which, at some stage, all the eggs are fertilized. As far as is known the production of males alone from parthenogenetic eggs is confined to the order Hymenoptera. 132 THE ANATOMY OF THE HONEY BEE. 1. THE MALE ORGANS. The reproductive organs of the drone are shown by figure 56 A. They consist of the testes (Tes), the vasa deferentia (V Def), the vesicule seminales (Ves), the accessory or mucous glands (AcG1), the ductus ejaculatorius (7D), and the penis (Pen). The testes of the bee (7Z’es) are said to be best developed in the pupa, at which stage they form the spermatozoa. ach consists of a large number of small tubules opening into a collecting reservoir at the end of the vas deferens. The spermatozoa pass down through the coiled vas deferens (VDef) and collect in the saclike enlargement of this duct, which constitutes the vesicula seminalis (Ves). In the mature adult drone these elongate sacs are densely packed with the active spermatozoa, while the testes that produced them become rudimentary. The vesicule when freshly dissected appear to be alive, for they bend and twist themselves about like small worms. Each opens by a short duct into the base of the accessory mucous gland (AcG/) of the same side. These organs have the form of two great sacs and are filled with a thick, white, homogeneous, finely granular quid, which is supposed to mix with the spermatozoa as the latter are discharged. The two open at the bases into the single median ejaculatory duct (7D) which opens into the anterior end of the penis (Pen). This last organ, shown in lateral view by figure 56 E, is an unusually large structure in the bee and is deeply invaginated into the cavity of the abdomen from the end of the ninth segment (D, Pen) as already de- scribed (see page 73). While the penis is simply an ectodermal tube, its walls present a number of very curious differentiations. The upper part is enlarged into a bulb (fig. 56 A and E, B and PenB) having two large irregular but symmetrical chitinous plates (¢¢) in its dorsal wall, beneath which is a large gelatinous thickening (B, ss). Near the base of the bulb is a double pinnate lobe (A and E, wv) - projecting from the dorsal wall. Below this, on the ventral side, is a series of close-set, transverse plates (EK, vv), followed again by large dorsal and ventral plates (ww and wxr). The terminal part makes a thin-walled chamber (A and E, yy), from which project backward two very large membranous pouches (zz) ending in blunt points. The whole tube of the penis is capable of being turned inside out, and it is said that copulation is effected by its eversion into the oviduct of the queen, the basal pouches of the penis (22) being forced into corresponding pouches of the oviduct, and the spermatozoa in the bulb placed near the opening of the spermatheca in the vagina. By their own activity probably the spermatozoa now make their way up into this receptacle of the female, the spermatheca, where they remain until ejected upon eggs passing down the oviduct. The spermatozoa received from one drone normally last the queen THE REPRODUCTIVE SYSTEM. 133 Fen AcGl / = W/E 7. VAAN NY \ —— ——— HCA AY THIN Ny MT ARAN wy tet (ite Mai Uy { ‘7 Hid il! (( . veut eh ‘ Ve \f ARN AY \\ if Wy ; tli aS Oem ~ yj H) yy / (ii oa ce ate Hail i \ : Pr, GON Fig. 56.—A, reproductive organs of drone, dorsal view, natural position ; B, inner euriice of dorsal wall of bulb of penis (E, PenB), showing gelatinous thickening (ss); ©, group of spermatozoa and intermixed granules; D, terminal segments of male abdomen, showing the seventh tergum (VJIT) removed from its sternum (VJJS) and the penis (Pen) partly protruded; E, lateral view of penis as invaginated within abdomen, and '—s ejaculatory duct (EjD). 134 THE ANATOMY OF THE HONEY BEE. throughout her life, so that after mating she goes into the hive never again to emerge except with a swarm, and her entire life is devoted to egg laying. The drone, on the other hand, dies immediately after mating, while those that do not mate are driven out of the hive in the fall and left to starve. ; The spermatozoa (fig. 56 C) are minute threadlike cells, capable of a vibratory motion. As found in the vesicule, they are usually bent into closely compressed loops, although many are extended to their entire length. One end is blunt, but not noticeably enlarged, the other is tapering, while the half toward the tapering end seems to be the part chiefly endowed with the power of motion. The sperm threads are contained in a liquid within the vesicule, in which float also a great number of minute granules. The vibrations of the spermatozoa keep these granules in constant motion. 2. THE FEMALE ORGANS: The organs of the female that produce the eggs are called the ovaries (fig. 57, Ov). In insects they consist of a varying number of egea tubules or ovarioles (ov) forming two lateral groups, in each of which the tubules converge at both ends, the anterior ends being drawn out into fine threads whose tips are connected, while the poste- rior ends are widened and open into the anterior end of the oviduct (OvD) on the same side of the body. An egg is simply a very large- cell whose size is due to the great accumulation of yolk in its proto- plasm, which serves as food for the future embryo. The eggs are formed in the terminal threads of the ovarioles and are at first appar- ently ordinary undifferentiated cells, but as they pass downward in the tubule they increase in size at the expense of some of the other ovarian cells. Hence the ovarioles usually have the form of a string of beads arranged in a graded series from very tiny ones at the upper end to others the size of the mature egg at the lower end. The two oviducts converge posteriorly and unite into the common median duct or vagina (Vag) which in most insects opens to the exterior upon the eighth sternum, as already described in the general account of the external anatomy of insects (see page 25), but in the bee and many ~ other insects the eighth sternum is entirely lacking as a distinct sclerite, and the genital opening is therefore behind the seventh ster- num and below the base of the sting. The posterior part of the © vagina is very large, forming a bursa copulatrix (BCpx). In addi-— tion to these parts there is nearly always present in insects a special receptacle for the spermatozoa called the spermatheca (Spm). This, in most insects, opens directly into the vagina as it does in the bee, but in some it opens into the roof of the genital chamber above the eighth sternum, when this is present, by a separate orifice behind that of the 135 THE REPRODUCTIVE SYSTEM. Fic. 57.—Reproductive organs, sting, and poison glands of queen, dorsal view. 1386 THE ANATOMY OF THE HONEY BEE. vagina. In the bee the two poison glands (AG/ and BG) do not open into the vagina but, as already described, into the base of the sting. They are, hence, oe special re having no homo- logues in nonstinging insects. The ovaries of the queen bee form two large gourd-shaped masses (fig. 57, Ov) whose posterior or basal ends are enlarged and whose anterior ends are narrowed, curved, and attached to each other. Since the queen lays eggs continuously during her entire life the ovaries always contain eggs in all stages of growth, and conse- quently do not vary so much in appearance as they do in those insects that ripen only one lot of eggs and deposit these all at one time. The structure of the ovarioles and the formation of the eggs in the bee have been specially studied by Paulcke (1900) and the following is a résumé of his paper: The terminal threads of the ovarioles are covered by a thin tunica propria and are filled with a protoplasmic mass containing transversely elongate nuclei in a single close series, but no cell outlines. Farther down, in the upper end of the ovariole proper, the nuclei become arranged in two rows, while here also the cell boundaries begin to appear; still farther along, where the cells are clearly defined, the latter become differentiated into epithelial cells and germ cells. Next, the germ cells themselves divide into egg cells and food or nurse cells. When first formed the egg cells occur in any part of the diameter of the tube, but they soon become arranged in a row down the middle of the ovariole and are separated by groups of nurse cells. The epithelial cells at this time arrange themselves on the periphery just within the tunica propria, but farther down they form a capsule or follicle about the egg and, less definitely, about the group of nurse cells at its upper end. The upper end of the egg becomes narrowed by a constriction of the epithelial capsule, which, however, does not shut it off from the nurse cells, a connection being retained with the latter in the form of a neck from the egg abutting against them. There are 48 of these nurse cells to each egg, which fact is accounted for by supposing that each original germ cell divides into 4, one of which ceases further divi- sion and becomes the egg cell, while each of the other 8 divides into 16 by four consecutive divisions. The latter are the nurse cells and their function is to nourish the egg cells. They persist down to the time when the egg is fully formed, when they suddenly disappear by being absorbed bodily into its yolk. Toward the end of the growth of the egg the follicle cells become thinner and thinner, so that when the egg is ready to go into the oviduct it has but a thin membrane to break through. The organs of most especial interest to the student of the bee are the spermatheca and the apparatus by means of which the queen is able to dole out the spermatozoa to the eggs as she deposits the latter. THE REPRODUCTIVE SYSTEM. 3% The spermatheca consists of a globular seminal sac (fig. 57, Spm), of a pair of tubular accessory glands (SpmG), and of a duct whose upper end is connected with the sac and receives also the duct of the glands, and whose lower end opens into the anterior part of the dorsal wall of the vagina just caudad of the united bases of the oviducts. The spermatozoa are discharged by the male into the upper end of the vagina, and in some manner they make their way up into the sperm sac through the duct. Cheshire (1885) described the latter as forking toward its lower end into an anterior branch which opens into the vagina and into a posterior branch which turns backward and becomes lost in the lower end of the vaginal wall. This second branch he believes is open in the young queen and is the one through which the spermatozoa enter the sac. Breslau (1906) has shown, how- ‘ever, that Cheshire was entirely wrong in his supposed observation >| a > of the forking of the duct, that the latter is a single tube, and that consequently the spermatozoa must both enter and leave the sac by the same conduit. It used to besupposed that the sperm sac had muscular walls and that it forced the spermatozoa out as from a compressed bulb, but Breslau has shown that this also is a mistaken notion, that the walls of the sac are entirely devoid of muscular fibers, and that the spermatozoa are sucked out by a muscular apparatus in the wall of the duct, which structure he names the sperm pump. Cheshire (1885) had previously described this apparatus in a very imperfect manner without recognizing any pumping function, for he supposed that by the relaxation of certain muscles the spermatozoa simply passed out of the sac and went down the tube. Breslau says, however, that the spermatozoa have not enough energy of their own to come out of the sac and, hence, do not need to be kept in by a special sphincter muscle, as described by Leydig. The upper end of the spermathecal duct makes an S-shaped bend just beyond the opening of the sac, and a number of muscles dis- posed upon this part constitute Breslau’s sperm-pump. Breslau shows that a contraction of certain of these muscles flattens the bend of the S and causes an enlargement of the lumen of the upper end of the loop. This, therefore, sucks into itself a small bundle of sperma- tozoa from the sac. The contraction then of other muscles forces the rest of the sperm-threads back into the mouth of the sac and drives the small bundle thus cut off down through the duct and into the vagina. Moreover, Breslau claims that this explanation is not theory only, for, by preparing histological sections from queens killed at different moments of egg-laying, he procured specimens showing the various stages in the pumping process and in the passage of the sperm through the duct. Cheshire calculated that a normal queen lays 1,500,000 eggs in her lifetime and that the spermatheca 138 THE ANATOMY OF THE HONEY BEE. holds about 4,000,000 spermatozoa, and therefore, allowing for drones, he concludes that there can not be more than four sperm-threads given to each female egg. But Breslau, figuring from the size of the sperm- bundle taken into the duct for each egg, states that each egg is actually given 75 to 100 spermatozoa. We feel that the latter calcula- tion must be much more reliable than that of Cheshire because it is based on an actual observation of the size of the sperm mass de- livered to the egg. Moreover, the myriads and myriads of tiny spermatozoa contained in the spermathecal sac make any attempt at a calculation of the number look absurd, and we can not believe that it is possible to even approximate the number present. Fur- thermore, as Breslau states, 100 spermatozoa make such an excessively small bundle that it requires a most effective and perfect apparatus to deliver even this number with anything like exactness—it is incon- ceivable that a mechanism could be perfect enough to give out only 4 or 5 or even 7 at a time. On the floor of the vagina, opposite the opening of the spermathecal duct, is a free flap provided with muscles, which is so situated that when elevated its end fits into the opening of the duct above. Leuckart (1858) explained this flap as a contrivance for holding the passing egg tight against the upper vaginal wall so that its aperture through which the spermatozoa is received, called the micropyle, would come against the opening of the duct and thus insure fertilization. Breslau, on the other hand, does not think the flap in question has any such function and he regards it as a valve which by fitting into the orifice of the spermathecal duct closes the latter and so prevents the pump from sucking up the contents of the vagina at the same time that it sucks a bundle of spermatozoa out of the sac. Since, however, the flap is on the floor of the vagina and is pressed down by the passing egg it is not clear how it can at such a time act as a valve to close the orifice of the duct in the dorsal wall, smce the pump is supposed to work by reflex action as the egg is entering the vagina, though, of course, it may so function before the egg has gone far enough to intervene between it and the duct opening; but it would certainly seem that a valve to close the latter, if needed at all, would be de- veloped in the dorsal wall of the vagina in connection with the orifice itself. Furthermore, a collapsible tube like the spermathecal duct, even though lined with chitin, should automatically close at its lower end when a suction force is applied at the upper end. Finally, Breslau attributes to the sperm pump not only the func- tion of delivering a definite mass of spermatozoa to each egg, but also that of sucking the spermatozoa up from the vagina of a newly fer- tilized queen into the spermathecal sac. He does not seem now to see in the valve any obstacle to such an action. The spermatozoa are usually supposed to make their way up the duct by their own vibra- tory motion. ea EXPLANATION OF SYMBOLS AND LETTERS. 139 The anatomy of the spermatheca and the muscular apparatus of its duct for delivering the spermatozoa to the egg does not, as Breslau points out, throw any hght on the determination of sex in bees. It isa common notion that all eggs of an unfertilized female develop into drones, but this is by no means proved; in fact, there is just as good reason for believing that, while no females develop, there are also no more than the normal number of drones produced—the eggs that might otherwise have developed into females, if laid by a fertile queen, all dying in'the cells of the comb, from which they are removed by the workers. Modern investigation of the determination of sex shows that there is probably just as much reason in many cases for supposing that sex is established in the egg of the ovary before fertilization, as there is for beleving it to result from fertilization or from subsequent en- vironment of the egg or young embryo. Hence, it is not only very doubtful that the queen determines the sex of her offspring by con- trolling the fertilization of the eggs, but it is also very uncertain that fertilization itself has anything to do with it. Parthenogenesis in the bee may amount simply to this, that the male eggs, predetermined as such in the ovary, are capable of developing without fertilization, while the female eggs are incapable of such a development and die if they are not fertilized. Each unlaid egg of insects in general has a small hole in the upper end of its shell, called the mzcropyle, which admits the spermatozoa to its interior. One or several spermatozoa may enter the egg through this aperture, but the nuclear part of only one unites with the egg nucleus, this constituting the fertilization of the egg. After this the micropyle closes and the egg is deposited in a cell of the comb by the queen. ‘The nucleus and a part of the protoplasm of the egg then begin to split up into a number of small cells which—but this is taking us into the development of the next generation, which is beyond the limits of our subject, and so here we must stop. EXPLANATION OF THE SYMBOLS AND LETTERS USED ON THE ILLUSTRATIONS. _ The writer has made an attempt to work out a set of convenient symbols for all the principal external and internal parts in the anat- omy of an insect. It has been found, however, that entire consistency is incompatible with practicability, especially in making compound abbreviations, and, therefore, the latter has been given first considera- tion in many cases. For example, the symbol Dect suggests the word “duct ” when standing alone much better than simply the letter D, but such combinations as SalDct and OvDct are unnecessarily long and the shortened forms of SalP) and OvD are sufficiently suggestive of “salivary duct” and “ oviduct.” The abbreviation Sc is used in such compound symbols as PsnSe for “ poison sac” and J'raSc 140 THE ANATOMY OF THE HONEY BEE. for “ tracheal sac,” notwithstanding that Sc alone means “ subcosta.” The symbol 7’ is used for “tergum,” and 7,, 7,, etc., and 17, IIT, etc., indicate individual thoracic and abdominal terga, but 7MWcl is used to signify “ transverse muscle.” And so, in several other cases, it has been found expedient to sacrifice strict uniformity to practical considerations. A combination of lower-case letters duplicating one entirely or partly of capitals signifies that the part so designated is a part or sub- division of the other, For example, Zen refers to the principal part. of the tentorium and ¢en to a minor part; P/ and pl are subdivisions of the same pleurum; Zmc/ and /mcl are both longitudinal muscles. The most logical method of referring symbols to any particular segment of the body would be, perhaps, to prefix them with either a Roman or an Arabic numeral corresponding with the number of the seoment. A common objection, however, to both would arise from the fact that entomologists are not at all agreed as to how many seg- ments there are in any region of an insect’s body. Furthermore, Roman numerals prefixed to all the symbols necessarily used on a drawing of the thorax, for example, would occupy entirely too much space. Finally, it is very desirable to have a method of referring to repeated structures without implying any segmental connection, and prefixed Arabic numerals are certainly most convenient and sug- gestive for such a purpose. A system often adopted to indicate the seoment to which a part belongs, especially in the thorax, is the use of one, two, or three accents in connection with the abbreviation. But accented symbols lack artistic unity, and some of the accent marks are too easily lost in the engraving and printing. For these several reasons the writer has adopted the following system: Numerical order of any repeated structure is indicated by an Arabic numeral placed before the abbreviation, and has no segmental significance. Thus 1P, 2P, etc., mean simply “ first parapterum,” second parepeonn etc; 1Gng, 2Gnqg, etc., mean “ first ganglon,” “second ganglion,” etc., without Ses that the ganglion belongs to any particular a Symbols are referred to the prothorax, ie mesothorax, or the meta- thorax, respectively, by the figures 1, 2, and 3 placed below and after them, except on the ies wher neh numbers designate the branches of the veins according to the Comstock-Needham system. The abdominal segments, counting the propodeum as the first, are indicated by the Roman numerals J to XY, and, when any one of these is placed before an abbreviation, it refers the symbol to that indi- vidual segment. The lower-case letters are used, singly and in pairs, to refer to miscellaneous parts having, in most cases, no individual or general anatomical names. A, AcGl, AGI, AGID, An, ANP, ANR, Ant, AntL, AntNv, Ao; Ap, Aph, Ag, Cd, Cer, CL, Cl, Cls, Cla, Clp, Clsp, 1Clsp, 2Clsp, Com, Cor, Ctl, Cu, . EXPLANATION OF SYMBOLS AND LETTERS. 141 1. SYMBOLS. anal vein; 7A, first anal, 2A, second anal, ete. accessory gland of male reproductive organs. acid gland of sting, opening into poison sac (PsnSc). duct of acid gland of sting. anus. anterior wing process of notum. anterior marginal ridge of notum. antenna. antennal lobe of brain. antennal nerve. aorta. apodeme, any internal chitinous process of body-wall. anterior phragma of any tergum, prephragma. the axillaries or articular sclerites of the wing base, designated individually as 1Aa, 2Az, 3A”, and 4A. accessory axillary sclerites of irregular occurrence in connection with the principal axillaries (Az). axillary cord, or ligament-like thickening of posterior edge of basal membrane of wing, attached to posterior angle of scutellum. axillary membrane, the thin membrane of wing base, containing the axillary sclerites and forming in some cases the lobes called alulee. bulb (bulb of penis or of sheath of sting). body-cavity. any particular part of body cavity such as that prolonged into the mouth parts, legs or pieces of the sting. bursa copulatrix. alkaline gland of sting. basement membrane. brain. protocerebrum. deutocerebrum. tritocerebrum. barb. body-wall. costa, first vein of wing. pollen basket or corbiculum on hind tibia of worker. crystalline cone of compound eye. eardo. cercus. erystalline lens of compound eye. cell, cells. claw. elypeus. clasping lobes of ninth segment of male, perhaps equivalent to the four gonapophyses of ninth segment of female. upper or outer clasper. lower or inner clasper. commissure (of either nervous or tracheal system). cornea. cuticle, the chitinous layer of the epidermis. cubitus, fifth vein of generalized wing. 142 Cv, Cz, CHP. Det, DDph, Dph, DphCls, Dphmb, DphMcl, H, HAp, EjD, Em, EMcl, Emp, Enz, Ep, Ephy, Epm, Eps, Epth, F, FI, For, Ft, FtCom, FtGng, FtNv, Fu, HS, gee ht, HtCls, AtTraSc, Int, EF. THE ANATOMY OF THE HONEY BEE. cross-vein. coxa. . pleural coxal process. duct. dorsal diaphragm. diaphragm. diaphragm cells. membrane of diaphragm. muscle fibers of diaphragm. compound eye. apodeme of extensor muscle. ejaculatory duct. lateral emargination of notum. extensor muscle. empodium. digestive vesicles formed by ventricular epithelium. epicranium. epipharynx. epimerum. cpisternum. epithelium. femur. flagellum. foramen magnum. front. frontal commissure. frontal ganglion. frontal nerve. furca or median entosternal apodeme of thoracic sterna. gonapophysis. 3 galea. gena. gland. large pharyngeal gland in anterior part of head of worker. salivary gland in posterior part of head. thoracic salivary gland. small median gland below pharyngeal plate (s). glossa. ganglion. gula. head. hooks on front edge of hind wing. hypopharynx. hair. surface disk of “auditory” organ of antenna, probably modified base of sensory hair. honey stomach. heart. individual chamber of heart. pericardial cells. pericardial tracheal sac. intima, the chitinous lining of any internal organ. tergum of first abdominal segment, the median scgment, or pro- podeum, incorporated into thorax. L, LO, LOl, LON», LbPlyp, HG, T7Cé, Lg, LGl1, Lin, Lm, LMcl, Imel, LmNv, Lr, LTra, Lum, AM, m, Mal, Ab, mob, m-CUu, MD, Md, IMdGI1, 2MdGl, MdNv, Mes, Met, EXPLANATION OF SYMBOLS AND LETTERS. 143 leg. labium. labellum. labial nerve. labial palpus. lacinia. lancet of sting, equivalent to first gonapophysis (1G). ligula. ‘‘ lubricating ” gland of sting (not shown in figures). median lobe of lingua or hypopharynx. labrum. longitudinal muscles. ventral longitudinal muscles of thorax. labral nerve. lorum. trachea of leg. lumen, the cavity of any hollow organ, whether the glossa, sting, alimentary canal, or gland. media, fourth vein of wing. media. median plate or plates of wing base. Malpighian tubules. intersegmental membrane. membrane. medio-cubital cross-vein. disclike muscle apodeme. mandible. outer saclike mandibular gland. inner racemose mandibular gland. mandibular nerve. metathorax, designated by figure 3 placed after and below any thoracic symbol. mnetathorax, designated by figure 3 placed after and below any thoracic symbol. the chitinous plates of the neck collectively, the ‘‘ microthorax,” individually designated mi. cervical (microthoracic) sclerites. median cross-vein. mouth parts or trophi. mentum. mouth. maxilla. maxillary palpus. maxillary nerve. notum. nucleus. nerve. ocellus. oblong plate. occiput. cesophagus. circumesophageal commissures. ommatidium. optic lobe. M et e first to fourth branches of pn, PNP, PNR, Pph, Pi; Prob, ProFs, eS. Ps: PSE: P sel. EST, Psn, PsnSc, THE ANATOMY OF THE HONEY BEE. ostium or lateral aperture of heart. ovary. ovariole, individual ovarian tube. oviduct. opening of vagina or median oviduct. paraptera, small pleural plates below base of wing, typically two episternal paraptera or preparaptera (iP and 2P)before pleural wing process (WP), and two epimeral paraptera or postparap- tera (3P and 4P) behind wing process. episternal paraptera, preparaptera. epimeral paraptera, postparaptera. arm of pleural ridge. postclypeus. muscle dise of episternal paraptera, giving insertion to pronator muscle (not present in the bee). peduncle. penis. bulb of penis. preepisternum. postgena. paraglossa. pregula. phragma. pharnyx. pleurum. Subdivision of pleurum. palpifer, palpus-carrying lobe of maxilla. palpiger, palpus-carrying lobe of labium. palpus. peritrophic membrane. pronator muscle. posthnotum or pseudonotum, the second or postalar tergal plate of the wing-bearing segments of most insects, the ‘* postscutellum ” of higher orders. small rod connecting postscutellum (postnotum PN) with upper edge of epimerum, probably a detached piece of the former (see figs. 22 and 24). posterior notal wing process. posterior marginal ridge of notum. posterior phragma or postphragma of any tergum, carried by the second notal plate or postnotum (PN), the * postscutellum ” of higher forms. internal pleural ridge, the entopleurum, marked externally by pleural suture (PS). proboscis. fossa of proboscis. pleural suture, external line separating episternum and epimerum, marking site of internal pleural ridge. presternum. prescutum. postscutellum (postnotum). poststernellum. poison canal of sting. poison sac of sting into which opens the acid gland (AG/17). Py, Pir, Pvent, Pvent Viv, Qd, R, RAp, Rd, Rect, RG1, r-m, RAfcl, 1RMcl, 2RMecl, Rs, ‘s, SalD, SalDO, Sc, Scl, Sep, Sct, Sga, Sh, ShA, SAB, SAS, Sint, S12, Slin, Smt, SeGng, Sp, Spm, SpmGl, St, StgNv, Stn, SinPlp, EXPLANATION OF SYMBOLS AND LETTERS. 145 sensory pit. peritreme, spiracle-bearing sclerite. proventriculus. proventricular tube or valve in ventriculus. quadrate plate of sting. radius, third vein of generalized wing. R.—Rs, first to fifth branches of radius. Rs, radial sector. apodeme of fiexor muscle. posterior extension or reduplication of any tergal or sternal plate overlapping plate following it. rectum, the large intestine of insects. rectal glands. radio-medial cross-vein. flexor muscle of mandible or wing. dorsal retractor muscle of ligula. ventral retractor muscle of ligula. radial sector, or second branch of radius at first forking. sternum. salivary duct. external opening of salivary duct. subcosta, second vein of generalized wing. scutellum. scape. scutum. subgalea. sheath of sting, equivalent to the second gonapophyses (2G) or middle pair on ninth abdominal segment. basal arm of sheath of sting. bulb of sheath of sting or ovipositor. shaft of sheath of sting. small intestine. sternellum. superlingua, embryonic lateral lobes of hypopharynx, true append- ages of fifth head segment. submentum, Subcesophageal ganglion. spiracle. spermatheca. spermathecal gland. stipes. stomatogastric nerve. sting. palpuslike appendages of the sting, equivalent to the third gona- pophyses (3G) or the outer pair on ninth abdominal segment. tergum. ) first abdominal tergum, the propodeum, incorporated into thorax. second abdominal tergum. tarsus. tibia. large tentorial arms of head, the mesocephalic pillars. slender tentorial arch over foramen magnum, testes. tegula. 22181—No. 18—10——10 146 T Mel. Tn, Tn, Tr, Tra, TraCom, TraSe, Tri, Vag, VDef, VDph, Vent, VentVlv, Ves, Vl, VMel, VNR, Va, W, WN V, W,N Vv, WP, Vv; W, THE ANATOMY OF THE HONEY BEE. transverse muscle. trochantin (not separated from sternum in bee). coxal condyle of trochantin. : trochanter. trachea. transverse ventral tracheal commissures of abdomen. tracheal sae. triangular plate of sting. vagina. vas deferens. ventral diaphragm. ventriculus. ventricular fold or valve in small intestine. vesicula seminalis. valve of sting carried by lancet. large vertical muscles of thorax. internal, median V-shaped notal ridge, the “ entodorsum.” vertex. wing. mesothoraciec wing nerve. metathoracic wing nerve. wing process of pleurum. 2. ALPHABETICAL LETTERING. clypeal suture. anterior tentorial pit, in clypeal suture. posterior tentorial pit, in occiput beside foramen magnum. thickened posterior edge cf lateral wall of fossa of proboscis. process at upper end of d articulating with cardo of maxilla and forming maxillary Ssuspensorium. internal median keel of vertex in cranium of drone. suspensorial ligaments of anterior end of cesophagus. pharyngeal rod. convolutions of dorsal blood vessel. anterior articular knob of mandible. ventral groove of glossa. ventral groove of maxillary rod. median plates of wing base. basal hooks of glossa. median ventral plate of ligula. dorsal plates of anterior end of mentum, supporting ligula. inner wall of canal of glossa. chitinous rod of glossa. pharyngeal plate, on anterior part of floor of pharynx. salivary pouch opening on dorsal side of base of ligula, receiving common duct of salivary glands (SalD). oblique muscles inserted upon dorsal side of salivary pouch of ligula. transverse or V-shaped suture on surface of mesonotum or metano- tum, formed by the internal V-shaped ridge or ‘‘ entodorsum ” (VNR). lateral lobe of pronotum projecting posteriorly over the first spiracle. bb, CC, dd, ee, tf, 99, hh, ii, iE kk, Il, mn, nn, 00, PD, qq, TT, SS, tt, uu, vv, ww, LL, UY, 225 EXPLANATION OF SYMBOLS AND LETTERS. 147 thoracic plate lying laterad of anterior part of sternum, often regarded as a part of presternum. accessory sclerite of fourth axillary (44%) of front wing, affording insertion for slender muscle (fig. 28, cc) attached below to common apodeme of mesosternum and metasternum. coxal condyles of mesothoracic and metathoracic sterna, probably really the coxal condyles of trochantins (fig. 4, 7nC) fused en- tirely with the sterna and episterna in each segment. muscle arising from inner wall of mesothoracic pleurum and in- serted upon outer end of corresponding scutellum, probably ac- cessory in function to the great vertical muscles (fig. 27, VMWcl) between the mesothoracic sternum and scutum. coxo-axillary muscle, extending from upper end of coxa to third parapterum (3P). muscle inserted upon accessory sclerite (y) of fourth axillary (4Az) from common entosternum of mesothorax and meta- thorax. notch of antenna cleaner on first tarsal joint (17ar) of front leg. spine of antenna cleaner situated on distal end of tibia (7'b). so-called ‘“ wax shears” or “wax pincers.” transverse chitinous band of empodium (Hmp), which compresses its two lobes when not in use and spread out by muscular effort. dorsal plate supporting empodium. ventral plate supporting empodium. dorsal groove of lancet interlocking with ventral ridge of sheath of sting. sting ¢hamber within end of seventh abdominal segment, lodging sting whose accessory plates are derived from eighth and ninth segments. reservoir of thoracic salivary gland. receptacular chitinous pouches on ventral side of pharyngeal plate (s) receiving ducts of large lateral pharyngeal glands of head (1Gl1). “ stomach-mouth ” at summit of proventricular projection within honey stomach (AS). pores on lancets (fig. 40 E) and shaft of. sting sheath (F) open- ing to exterior from prolongation of body-cavity (bc) contained in each. gelatinous layer secreted upon inner surface of ventricular epi- thelium. food contents of alimentary canal. cells of ventricular epithelium apparently forming the internal gelatinous layer. cartilaginous mass on inner surface of dorsal wall of bulb of penis (fig. 56 HE, PenB). dorsal plates of bulb of penis. fimbriated dorsal lobes of penis at base of bulb. ventral scalariform row of plates on tube of penis. dorsal basal plates of penis. ventral basal plates of penis. basal pouch of penis. copulatory sacs of penis. 148 THE ANATOMY OF THE HONEY BEE. . BIBLIOGRAPHY. ABONYI, SANDOR. 1903. Morphologische und physiologische Beschreibung des Darmkanals der Honigbiene (Apis mellifica). Ablatt Kézlem., II, pp. 137-168, pls. XI-XIV. ARNHART, LUDWIG. 1906. Anatomie und Physiologie der Honigbiene, 99 pp., 4 pls., 53 figs. Wien, 1906. [Extract from “ Allgemeines Lehrbuch der Bienenzucht” by Alois Alfonsus. ] Borpas, L. 1894. Anatomie du tube digestif des Hyménoptéres. Comptes Rendus de PAcad. des Sci., Paris, CX VIII, pp. 1423-1425. 1894. Glandes salivaires des Apine (Apis mellifica ¢ et 8%). Compte- rendu de la Soc. Phil. de Paris, 1894, No. 4, pp. 12-14. 1894. Glandes salivaires des Apine (Apis mellifica % et ¢). Bul. de la Soc. Phil. de Paris, 8 ser., VII, 1894-1895, pp. 9-26, 9 figs. 1895. Appareil génital male des Hyménoptéres. Ann. Sci. Nat., X-X, 7 ser., 1895, pp. 103-181. BREITHAUPT, PAUL FRANZ. 1886. Ueber die Anatomie und die Functionen der Bienenzunge. Arch. f. Naturg., LIII, pp. 47-112, pls. IV-V. [Brief summary in Journ. Roy. Micr. Soe., VII, Pt. I, 1887, pp. 224-225. ] . BRESLAU, ERNST. 1905. Die Samenblasengang der Bienenkoénigin. Zool. Anz., XXIX, 1905— 1906, pp. 299-323, 7 figs. BEranr, TP J. 1884. On the anatomy and functions of the tongue of the honey bee (worker). Journ. Linn. Soc. London, Zool., pp. 408-417, Pls. VEL OLX. CARLET, G. 1884. Sur les muscles de ’labdomen de l’abeille. Comptes Rendus de l’Acad. des Sci. de Paris, XCVIII, pp. 758, 759. 1884. Sur le venin des Hyménoptéres et ses organes sécréteurs. Comptes Rendus de l’Acad. des Sci. de Paris, XCVIII, pp. 1550, 1551. 1890. Mémoir sur le venin et l’aiguillon de l’abeille. Ann. des Sci. Nat., Zool., 7 ser., IX, pp. 1-17, pl. 1. 1890. Sur les organes sécréteurs et la sécrétion de la cire chez labeille. Comptes Rendus de l’Acad. des Sci. de Paris, CX, pp. 361-363. CHESHIRE, FRANK R. 1885. The apparatus for differentiating the sexes in bees and wasps. An anatomical investigation into the structure of the receptaculum seminis and adjacent parts. Journ. Roy. Micr. Soc., ser. 2, V, pp. yes) Bye Sl (awe (oe BO 1886. Bees and bee keeping, 2 vols., London. (Vol. I devoted mostly to anatomy of the bee.) CLERICI, F. 1875. L’Ape sua anatomia—suoi memici. Milan. [80 colored plates drawn from anatomical preparations by G. Barto.] Cook; A, J; 1904. The bee keeper’s guide, 18th ed., Chicago. COPELAND, MANTON, and MARK, E. L. 1907. Some stages in the spermatogenesis of the honey bee. Proc. Amer. Acad. Art. and Sci., XLII, pp. 103-111, 1 pl. BIBLIOGRAPHY. TAG Cowan, T. W. 1904. The honey bee, 2d ed., London. DJATHCHENKO, SOPHIE. 1906. Zur Frage der Athumsorgane der Biene. Ann. de I]’Inst. agron. de Moscou, XII, pp. 1-14, 9 figs. DREYLING, L. 1903. Ueber die wachsbereitenden Organe der Honigbiene. Zool Anz., XXVI, pp. 710-715, 2 figs. FOREL, AUGUSTE. 1907. The senses of insects. English ed., translated by Macleod Yearsley, London. GIRARD, MAURICE. 1878. Les abeilles. Paris. GIRDWOYN, MICHEL. 1876. Anatomie et physiologie de l’abeille. Mem. de la Soc. Polonaise des Sci. Exac., VI, 39 pp., 12 pls., Paris. [Also published separately. ] HoMMELL, R. 1904, 1905. Anatomie et physiologie de labeille domestique. Le Microg. Prep. oot, pp. 49-60; pis: XXVIII, XXVIII; XII, pp. 15-25; 60-67. 1906. Apiculture (Encyclopédie Agricole). Anatomie de l’abeille, pp. 20— 103, Paris. HUBER, FRANCOIS. 1814. Nouvelles observations sur les abeilles, 2 vols. 2d ed., Paris and Geneva. KENYON, F. C. 1896. The brain of the bee. Journ. Comp. Neurol., VI, pp. 1383-210, pls. XIV—-XXIT. 1897. The optic lobes of the bee’s brain in the light of recent neurological methods. Amer. Nat., XXXI, pp. 369-376, pl. IX. KOSCHEVNIKOV, G. A. 1900. Ueber den Fettkorper und die Ginocyten der Honigbiene (Apis melli- fera L.). Zool. Anz., XXIII, pp. 337-353. KRAEPELIN, K. 1873. Untersuchungen tiber den Bau, Mechanismus und Entwickelung des Stachels der bienenartigen Tiere. Zeit. f. wiss. Zool., XXIII, pp. ‘289-330, pls. XV, XVI. Lupwic, AUGUST. 1906. Unsere Bienen. Die Anatomie, pp. 34-112, Berlin. MACLOSKIE, GEORGE. 1881. The endocranium and maxillary suspensorium of the bee. Amer. Nat., XV, pp. 353-362, 6 figs. _ Marx, E. L., and CopELaNnD, MANTON. 1907. Some stages in the spermatogenesis of the honey bee. Proc. Amer. Acad. Art. and Sci., XLII, pp. 108-111, 1 pl. MEVES, FRIEDRICH. 1908. Ueber Richtungskérperbildung im Hoden von Hymenopteren. Anat. Anz., XXIV, pp. 29-382, 8 figs. 1907. Die Spermatocytenteilungen bei der Honigbiene (Apis mellifica L.), nebst Bemerkungen tiber Chromatinreduction. Arch. f. Microsk. Anat. und Entwick., LXX, pp. 414-491, 5 figs. pls, XXII-XXVI. 150 THE ANATOMY OF THE HONEY BEE. MICHAELIS, GEORG. _ + 1900. Bau und Entwickelung des minnlichen Begattungsapparates der Ho- e nigbiene. Zeit. f. wiss. Zool., LXVII, pp. 439-460, pl. XXVI. PAULCKE, WILHELM. 1900. Ueber die Differenzirung der Zellelemente im Ovarium der Bienen- — konigin (Apis mellifica). Zool. Jahrb., Anat. und Ontog., XIV, 1900, 1901, pp. 177-202, pls. 12-13a. PHILLIPS, EVERETT FRANKLIN. 1905. Structure and development of the compound eye of the honey bee. Proc. Acad. Nat. Sci. Phila., LVII, pp. 123-157, 7 figs., pls. VI-VEE PISSAREW, W. J. 1898. Das Herz der Biene (Apis mellifica). Zool. Anz., XXI, pp. 282, 283, feito? PRANTA; “AQ iVON: 1888 and 1889. Ueber den Futtersaft der Biene. Zeit. f. Physio. Chemie, XII, 1888, pp. 827-3854; XIII, 1889, pp. 552-561. PLATEAU, FELIX. 1874. Recherches sur les phénoménes de la digestion chez les insectes. Mém. de Acad. Roy. des Sci., des Let. et des Beaux-arts de Belgique, XLI, pp. 3-124, pls. I-III. Roor, A. 1.,-and. Reot, ©: Rh. 1908. The A B C and X Y Z of Bee Culture, Medina, Ohio. SAMUELSON, J., and Hicks, J. B. 1860. The honey bee. London. SCHIEMENZ, PAULUS. 1883. Ueber des Herkommen des Futtersaftes und die Speicheldriisen der Bienen, nebst einem Anhange tiber das Riechorgan. Zeit. f. wiss. Zool., XXXVIII, pp. 71-135, pls. V—VII. ScuMiIp, A., and KLEINE, G. 1861. Umrisse zur Anatomie und Physiologie der Bienen. Die Bienen- zeitung, I, pp. 498-525, pls. I-VII. SCHONFELD, PASTOR. | 1886. Die physiologische Bedeutung des Magenmundes der Honigbiene. Arch. f. Anat. und Physiol., Physiol. Abth., pp. 451-458. SEADEN. EF. W.. Li: 1901. A scent-producing organ in the abdomen of the bee. Gleanings in Bee Culture, X XIX, August, pp. 639, 640, 1 fig. 1902. A scent-producing organ in the abdomen of the worker of Apis mellifica. Ent. Mag. Lond., XXXVIII, pp. 208-211, 1 fig. Wor, O..5. 3B; 1875. Das Riechorgan der Biene. Nova Acta der Ksl. Leop.-Carol. Deut. Akad. der Naturf., XX XVIII, pp. 1-251, pls. I-VIII. ZANDER, ENOCH. 1899. Beitrige zur Morphologie des Stachelapparates der Hymenopteren. Zeit. f. wiss. Zool., LXVI, pp.. 288-333, pls. XVIII, XIX. 1900. Beitriige zur Morphologie der minnlichen Geschlichtsorgaine der Hymenopteren. Zeit. f. wiss. Zool., LXVII, pp. 461-489, 9 figs., DL-ceALY El. INDEX. Page. 2. DL ERRSDS SSPE! ea i Se alee ae gee i nent ae re at a are Pep See eee 13-14 REC eS ee SY 2 fe Os eS Bled ee wa es 2 85 24-26 EINE AEG et res rie eee sos st 2 eid eo eos gues ete 69-71 SEES TSE FES pe sa i ae cla sine tes ee ve teen ieee 118-119 maxeolannds aN SHE. 552: 62 Seas 5s eee sy SoS 69-83 wae DET SNE. oes Goce See Eee glee gpg aoe 104-105 mecessory sternal plate in seneralized thorax. _ .--.:.-.-.-..----------.-2-2-- 24 SueINNRPOR ONE ME ATMA kent So oe 9S wk See geet eee a SR RE 79 RBIRn PEN REM MC DE a eS eee een ia oe Re ee ST eo Pee RSL 90 STOTT ae SS Si I gee ay rg ey ee 84-106 meine oe rited een et ee ed ee Sek ee eel ee ss 79 ene Repeat eters ered eet Se Selo be os bas SoS ein Se ee ees be hh 383 86 elles CIN OL PONE T NIZE Wie 2 1S bse seeds sleet yee ete) eee bees 22 igen geet sas 2 So eo ate. oP Sk aes bos be SS 4: 59 EvMM EN PENT C AT OLAMGS tte a 22 Dae bo 8 Sonos esse dee oS Se bse 92 ESE STD EN pia See ea 15 op TEER 2 Ee es ee a a ee ae 66 peineein: ister aor Celine OrAems S25 sk 2 od ose ee Se ve Se ee 32-39 preety eee pens pe Any oo ae Le le eee 16 aie TAL tar re a ae es Ce) wos, hee E Le cee 27, 32-33 Bilas atic ies eee aa ee ee a ee ae it ae 36-39 PEERS UR SE SS a ee 125 Pn erioOrsopal wie mrecess, Gelmed 2.2. 2.2.52... 5.2.2 .22.2 22222 e eee e le. 19 pL_Merotinorax Of honey bees. 22_ = 25 522. 2225. 62 metainorax OL honey bee. .<. - =... 22-25 2522 56 PEM Mra Alar MACOS 9 ooo 2 se sn 2 ee See eee 92 MULES Mee Sees te ep eo Oe OE eee Poke eae ee 78 Of ie se Sas SS Ee aaa are re 108-109 SPNIDN, SEP E EE iN iste oS So AS ee ee So on ee ese oe Soe 32 TD EEE SED ge a cee 12-13 SENN abnrEr IRS e arse fe eo) gh Sa) deel bie eee Pe se et eS 84-87 en ii aOR aE 1a tet tage ee 6 Gs sae’: Se Sak See ee ae Miewamr termrm Honey bees 2220.8 ps Sos Sk Sole. 2 62 mugewiur OF BOneCY bee. 37522 oS sesh 2k. 23 et ener 62 2 Se ee ae Oi ease Re See A aS 59-62 Mn RINE Ee eae he ere ae oe = 1s oh ade dle Pea ede paced C2 19 GENERA WADE 2.5 55 5 Se oe eae ne ot pee Mos CL SEE ERLE 23 MINCE Seah eee Po oat pe RE ee aR Se 62 mpimeat- eee PCneralized Wink 22. 2 225.2222. S220 8S. Le ete le 23 RETA Sed Sel WE ee Ors ey ee Ee 61 Basal ligament of wing. (See Axillary cord.) aE SED ESS a ag ee esi Bees Sees hay 129 LD ESEMTELE TUTE PES ie 2 | a a eR a 18 EEE tee She es ns Ss PL ee ek wo a ante Bids eee 107 EAE IIIs sere SS yt eS ee a es cu Sah eae 14-15 152 THE ANATOMY OF THE HONEY BER. Bombs, pharyngeal elands. 2 e.. sys 7 oe oe ca Bouton. 02 S.°. 2 Pc es Brain, general descriptiot._ 2.2.32 SS Ase eee 124 of honey bées. 2 Js sas2e5 Soon cba ee 125-126 Brood fod: 29.25. 4 See Ba Se ee eee Pe ares 92-94 production of, and summary of facts known concerning it ......... 98-101 Bursa copulatrixs.- Coss 2 24h es We oes a ee 134 M@arnohy crates 2-2: ese eee wii ie 8&9 Cardo, defined . 22.7.2 22.2 2. 6k eee ~ aa ol honey be@s. oo. eee eo a ee 45 GCells:of body,.defined ... 2020.9 .2 sn ee ace ee 84-86 wane: defined.02.- 2a) er. Abe be Ae eee tree Pp > a Gerci,, defined 2.2203 se. 8205208 (ge ee ee eee 24 COLVICUR: seo. Sot men ee Se ee ae 13 Se hnaemia-anWer Se 5 oe ee ee ee ae ee ae ee pp ete 12% OULED 2 ot. ee se Soe Se ey Se eee se eee ee ig ee@hiyle” coco. hot, Pa oe eo ge Se 101 “stomach”. 22.251 ls pate ee ee ee 90 ERULYV IMC” ee 2 Sia, te ee Shh 2 ee eee ae ee 101 Circulation of the blood: ..2 4. 2235 Seat eee eee 107-111 Circulatory system. 222 ac oe ae ae ee 107-111 Cireumcesophageal commissures, defined: _. 2. ...02.-2.22. 124 in-honey bee. .22. 2.5.24 2s ee eee 126 Claspine organs, defineds. s2...2 042580 25, le Se ee 24 Of GORE. = 5 is fsa eeinn es axe doo bs ea eee \ 72 Slaws OL tarsus: o2.: «1.565 cis Ge Bee ee * Ol 22, 68-69 Clypeal suture). : =. oso. 2 - sees ee Ro ee ee ee ae Ciypeus, detined > 23s... 22. 62. saee hes hee ee ke 15 of honey -be@es...2 562 32 cee eee ee eee 28 Gockroach,. Blatia, development, ob head =... 324235. 5a ee ee eee 18 Sonminiiscurés. 0 oS So Res eh as ee ee 7 124 Pompound eyes... .5oehe0 bec ea ee 27 detailed structure-<20225) 23728 ee 127-130 Benacephalius, OVIPOSiWer . 05. =. 02 oo, ea ok VR A ee 25 Morbicwls . 3.5. <2. 00s. eS ee ae Ls ee ee eee eee 66-68 Rorne ss i oe Se oe, oe A a 27, 127-129 Gorteal pisment eels. oc. 3 eo ee ee Oe 129 Cpsta of generalized wings: ..2s cass. os ee ee ee eee ee 22 Hymenopterac....0 04: 4.3 Po sce sa eee ot ee ee 59 Coxa, defined =.%.2 22. 22521205 28 beeen ded oe a ee ee eee 20, 22 of honey beé. 25.2.2 2g .05 on be Se ee eee 67° Coxo-axillary. muscle of wing of honey bee ......-:.-:.i..2. 2 s25e ese ee 66 Goxostermpm. 2.0540 2 oes ee ao oe a eens Poe ees BE ee ee eee 21 Granium, internal structure. =... 2.6. 2) ie) ee. sie ee ee 30-32 Cricket, Gryllus pennsylvanicus, mouth parts. <: 2. . 2.222220 0s =e = ee 16-18 bxop, defined: --- 22 coon 5 eos eh oe ee ee ee 90 of honey bee-(honey stomach) - 2-4 :242--2224: 22: 2o552 2-5 See oes 94-95 Gross veins of generalized wing..-2-./.....22 1 2.3.22 ke ee ee 22-23 Crystalline cones s2..025-220 Sess Pe ee Po ee 2 129 lensgi si 23 os beds s bad sec Se ae eee 129 GOO. 2 ron ub pene s 8 ee ee eee 129 Cubitie gemoneralized wing ioic: 660 yes eee eee 2, +5 e ee 22 60 Hymenoptera: 200.2225. adn obs ds bot oe Le eee INDEX. | 153 Darts. (See Lancets.) Page. ME MMEGNG PS) o STCCIMGLETNUMI 6222 5zcbus 556 vi ae. SSS ee he 20 enn an manelcs a: wil or NOney DEC 2.222528 2.222. s ooh et le Le 64 Pe ceummetenorces ia nomey ees. 22) 22 ole 22.5 Se ck el pete eee loll el 2 139 o EULUPO BEDE SESE Ss PEC Tae ae gn a 124 AME ICEMAN tas cs ies Sen oes ave Meme eI Ee OF 125-126 Seean iri cine tr ere te ete a Sd ee i OS ee es 11-12 eeapcemmmeetinerr rrr ee Mie ee. eo eG et ote lee ee ole eee Tee 110 Periqeeires ta nde caret pee ON ee ee oe le eh one eee: 107-108 Saran eee eins. Ln ae eres Le a ee eee! 109-110 PSLES NEENIE ce iy ea oR a ag RE Ae ere ear ioe ga 109 ec eae eren eee ee ee ee ene JS ee ae ae eee 86, 89 assimilation, and excretion, general physiology.:..-.-....../...--:- 84-87 Mees aaa a ere eee are Ye nian a oes tek eee HS Se 109-110 STV Sag 3 5 eee re et TP rae 107-108, 111 Seer cen TAMA eee Oe ane et oe sien SAL Set ee ek ae ee tata ee 126 Meee nee oe! es el wet a. Whe Se NS SAS 18 we DDC USELESS a ane pt er eat a 2 TRS Mert ee eenra orien eta eS eal ae a Se tae SE ne 132 rn HE ete oe ere ee ee MOORS SLES ST eR LE Se oases 130 Pertti NoMa er se ae Re Pee Seri oh eid aa Soe. : 137, 138, 139 PSEA LION Moye hte ae 8 ie aes Sa SSS Le SRT Pines RNR NL a eens 136 Pea iprm mniscies ai wane of honeybee: “5.222.520.2224 25l5. i leo 22a... 64 ReMGER ONE ees OA ear es Ree Pe FS ofS Se oe Pa eee 12-14 Mmbrvontc Gevelopmcnh denned. 50. 252 j25. 22. ee ets ee eee ee ee 12 PeNNGa eMC dae: tobe ek ee) ee Se Ee a es ole - 20 ; PisOnEV eee es eee ten eae D8 or Re ee ee es 68, 69 Sipeegh ascii Peer eee ay NY Phe etek OS Se eee holes oe bee ar bea) Semmienuiunend amide 5 eee ope a rah el Sek beens 08 19 PRE IIN i e EEIEM fe tae hn She Pe Ss Se Tee Se eee 19 of mesothorax of honey bee. (See Pleural ridge.) LUPE BEES USCVGE, G2) 027 7s C001 610 lala ea age a ng 21 Bearnie GiMMOney OCR. 8 2. ee 55 mesothorax and metathorax of honey bee..............-. 56. LPS RLIL eS STA 5 SAO Saga ee el get a PE ene IO) 19 net eMC ede ie th Se en deo eee eb eee ae, een errs rameter cut fee Pa ne. Ws ns Soo oe ee Bae oe be 87 0) DETER REL (ERE 2 beeline 16 Peers paramiera postparaptera), defined:.....-....-.-.-.-.0./225....--.-- 20 of mesopleurum of honey bee-.:-...-..-- 56 EL. LE SEL SS cc gee, SaaS ge Reet ag gee ey 8 ee a 19 Mem mneiram: oLhoney bees. 22208225. 7k eC ee PEL 56 mum Mena Tamir nae tae) FS its bee RI Soe es 16 TLE EECEE ED Ts EB oS air Nd A a ey ae gg NE A ge 51-53 ; sence Orraits: 2! 222.0. Ser ee a Spelt Se) ieee eee gi PE 8 TEED Eg ESBS e TS ERE aa a i a see le RN ly ec ea cae age 24 Perera Haraptera (preparaptera), defined....:-.2........52..-..:--.---..-- 20 of mesopleurum of honey bee...-...--.-..-- 56 el LEE ELE Ta Si ie sete ork 5 Ree og in ie Oe ee age 19 MmemecmmCurniton None y DEO lls. See tie te ee So 22S 56 rth sees a 2 Tot ne So ae ag ite eo ea er ne Raa 84-87 Secnsor muscle of mandible of honey bee..............:..-...-----.-------- 40 eternal venital organs of drone honey bée....................---.-.-------- 72-73 154 THE ANATOMY OF THE HONEY BEE. External mandibular slands>... 2222: 922 ec 2 ee Eye, compound... =... 652 5 ee ee ee SIMple. 2. du. Shoe Sek ee oe eg ee Faeets of compound eye: :. 5.222.252 5 ee ee ee ee Wat body =~ 2.250555. Woe es Soe ee 119, 120 and weno yles. 25.2202 bass a ee oe 119-121 Female organs of reproduction. .- - 2.22... 2s Pee 134-139 Femur; defined ._...- 22.5 3023220 ek oe Le ee eee eee 22 ot honey bee. 2. 2... Seek ee ee ee ee 67 Hertilization of cog, detined 2 (- tas S ae Ce ee eee ee > ood a Gee 130 of honey bee... 25... 2.22: po eam Ee eS. 137-139 First abdominal segment (propodeum))—......0-. 225 sos ee 58-59 Migsel him 2.02 22325 222 ee ee ee 32-33 Flexor muscle of mandible of honey bee... 22... .2) 2 Se eee 40 wing 01 honey beé.. 2.02.2 eS 65 Kood of adult honey ees: < 3-22-02. ee ee ieee 89 larve. (See Brood food and Royal jelly.) Foramen magnum, defined .. 22.222 ss oo 22 ie 5 bee ee eee 15 ot head of henéy beei2: 22610 se ae so eee 28 essa Obs PrOUDOSCIS 282 3002 5 2) i ee ee ee eee ieeeretae rama oe 28, 46 Hrontal eanehon.« 2.02255 Shik ee ee oe 125 Rront, defined 2 o/o8 es ono Sta he ss oe cree 15 of head: of honey ‘bee... ) 2.4236: Ho a Eee ee 29 Furca (entosternum) ; defined): ._ 2.2.05. SA eee 21 of prothorax. of honey bee!. 222... =. eee 55 mesothorax and metathorax of honey bee...........-.-. 56 Galen, defined) 2.2. Jo 2 Ses Ce a ee ee a 17 of maxilla of honey bee.) 2.222202) 2 eee 46 (aanelia, defined :. 3... 22.00 se ede ee ee ee 124 ‘“(Gqaumensepel 222 i bone ees ee et et 52 Genz.. defined 5) oo csc Soe ee ee ee ee 15 of. head of honey bee-..2-% 2. ee ee ee 29 General physiology of digestion, assimilation, and excretion...........-------- 84-87 Galls, ‘defined «4. .= 9.2252 ic.o2 fn So oe a 112 Glands. external-mandibular._.. 22-02... 2 2 ee ee eee 4] internal mandibular. 2:2. 0.29.25. eh eo eee 42 lateral pharyneeal... v.22... eee Se eee eee 91, 92 median pharyneeal.. 2. 222. sh) se ae ee 91 mucous glands of male orpans...-.-.5.22.-5.25<: 522 4-26. 132 of Nassanoff.2.22 2 222 cel ek ee ee ee eee 83 SHING. 5 oc ie ent ets aes 1 Ee ee ee 78-80 MONE oo of Sk a eb ete ON a ee Se 78-79 alkalivies: 2.02222 ba oo ei ee ee 79 ‘lubricating 7) oi tee 22 ce ee El as Ve en 78 posteerebrale: 2.05. se. she es oss oes a ee 87-88 rectal 2.55.5 eon ites ce ee Sah ee 90, 106 salivary, ofcheadeie 0 oes cee oo ce ee ee ele 87-88 thorax” = 0.252023 2 Sa ee 88-89 siiblingtual. 55 vcis2s oocss doe ee ee ees eee 91 supracebebral. 22205000. ago ant sso ee Se 91 Gloesa defined... Axio US ea) ee Seiad oo ence 5S ae 45 details; im worker.of lonéy hees2.2. sect ee ee “SSA eae 48 Gloss, defined... . 530 scet 82 See Pee ee ee 17 of labium ef generalized insect... 222-5. 22.234. $ase53 eee ie ee INDEX. 155 Page. i PEE Lig ee SBS eee a ee eee 48 Ree RE CMe emer s A eae eS Soe we ac lee ee Sts 2 He = 24 of ovipositor of longhorned grasshopper.......-...-.---------- 25 Spe O MUN GHERD Nera fe 88 tote oS oe 76 Grasshopper, longhorned (Conocephalus), ovipositor........--....------------- 25 SP wemminaneel tata ee, Oe SO Sk. ee bed Soe, tees 2 11 no Senna w Manis mIeNIA) Parts. <..2.2 0. 2 so ee eee ee See 16-18 RRM ers Sa HEae ae Sr eee eS eo Ss et Set ee ee 16 Head, defined ....-. Ree tae ey Neto LAD ee Pin. VS es 15 Be One nee Ala ai AppenGares..2 2.65 5. Sse eo ee 26-53 Rie RMA ANCTAERE en pone KS Ba ee a ed Oe 26-30 EEE Chm?" ETS ERTLG 1p or Se eee ace pe elles a ap Pie eee 30-32 worker, queen and drone, compared -.-..-.-..-.-.------ 29-30 Pear) chambers: oc. 20.22 8-22 eS LE A TIO POE Re ee gee EOF. 108 Pee eager CEIEb Halen) ore 2 Rt ay nh Se EO et 2 NE oa 108 SEE LESEVER SCS Se Ae oe ae ee de are ee oe mera oe 109 TILEY LE ROUTES oS TS 2 5 eo eager 90, 94-95 Bormiail, Sirer flavicornis; first. abdominal segment ..:....-......-.. 222.25. 58 Te ATT eee ee se ee 57 PTD RRR CAEIR -co sae eee 56 Rostgena, denned. 2:2. ess. 2 2 ve ke ee ees Sk gee ne eee 16 of head of honey: bee. 2s. Seo ues Pe th eee ee ee 29 Pestnotim (pseudonotum)-detined..205.5. 2222.22. 2st. ee ee 19 of mesotergum of honey bees>.- 32-2625 eee 55-56 Restparaptera, defined:<. 22... 2.25.22. 2n te 2 ee 20 : of mesopleurum of honeybee. - = 22222 = 9 eee 56 Postscutellum, defined: ....2. 722 25 ea ee 19 oF mesotermum of honey bee =>. == ‘iced os 1a eee 55 Poststernellum, defined. ..-22 25 2202222 is ee eee 21 Preepisternum, defined... v2.2.2. 5.22 .- eens a eee 19-20 Ereoral cavity 202s i242 eh ee ee 49 Ee parapLerd, CeCmmed ett: acta ee “Lops it eh nt a Stee a ae 20 of mesopleurum of honey bee. 222. 222 s5-25 2 ee 56 Prescutum, defined... 0502-22326 5252 34 ee ee 19 Presternum, detined:. 20. 522-2. a Se ee ee ee 20 ProOWOSCIB: 2. of .Sais Sa Vegan SSO Re 27, 43-51 Pronator apparatus of wine... 25.522 022.2 2S 2ne5 2 ee ee eee 65 Rrepodeu mgs o3 jo os cae et ee es eee poe a te oleae age 58-59 Proteids: ..024 2.2 22 lek SS Ae ey a 89 iprotworax; detined’ 25.) J int pias i etek eed GOVE tees cS of honeybee: 22. 2 ee 55 Protocerebrum, defined. : 2.5.52. 02 4 ek eed 3 ene le eee ne ee 124 in honey bee... 25 kek Jee SE See ee eee 125 Protoplasm. ...- ogee ah eels eS OS is BE eek a cae ee 86 “’ Protractor linguse’’. 2.2.2.2. 5.2 22:22 ee ee 51 Proventricular valve we. 2533 2.4 Tee kde ke oe ee SA” een W ce” 97 Proventriculus; defined. (2 2.22052 50 Si oa a eae ee 90 of honey bee’... <= 2...25 ve4ses. ee oe ore eae 95-98 Pseudondtum, defined: ..-.2. 3. tar ed ine eee ee 19 Psithyrus, pharyngeal glands..2-. 22...) 2.325 5 is hs see aie ebe ee re 92 INDEX. 159 : Page. MII ME er fame cee ene eee secs SLL estos eect. sans see 22 LPS Lc STE ee eee ee a ee Se Se at ann 2s a 12 Popal stage, defined. .-..22.--.:-- oR Wate pa nos a te eg ee ae seer he ge 12 MauMnrreaniaic er cine OL money bers. 25 iy seo-/ 8.2 2S. clea. lee: See 76 REED T(E SS Pe os Ss BR ts eh ea a ea 130 ORME TNE RIUM Cre as a bi DS A SoS tie eset sl sok. 130-131 ere medial Cross get GCnned: 222... bale oS oe onde eles eee ee. 23 emer Nel ener cee wart os er. 8 82 ee ee 22 SNAILS TTC OTE Se Aon Mga eS le cy Oe 59-62 Dee ee MMP r een Meco Go a Ss LE oe 90 pie eede Ce oe eee en ss yd ik Ge ke Uk ENS ass 106 cee Oe nee nn tae esp et 8 ee ee Sa us Ln eere e fe 90 BERD ED EES See ee eC eer ee Sn a nena ape al | Perueeseeiaa emir etin: oe geet ee a es oe ee Se See el eek 130-139 RegeetOl Meee ney tere = he Se TL ae Eo Oa ee 132-134 TUTE STIS OTe: i tes Reae ae RR i Se ae de Sp a y ee e 134-139 Peers ath Wi VeMmiemts Co < = 5 5. 2-2. eek Sb aes oe ee 8 ee eae t ssl 118 PETES SSS SS Ee Te ee rs A a gt a nn aa eg gt 118-119 Fane a att ee ae A eed OE Sage ee ess Soe eee dace l oo: 112-114 ESTE EERE SS i a gna, an 112-119 ens a ye eee nn eee ey) a SN Reet. oe Pes ede See ae 129 (LEE SRE ess 2 oS OS Ea a oe er a gs 51 Gouna yg Uae ee es pO eho, SS. oe alee Sa 51 Beinnoimern on conipoluiiiroyes-.. _ 22. Joes 8s 25 S823. 2s Lee beset eee 129 Subeeetebte OnICUMICMN Ee 2. foe as ee Ae a be eee. oad She bs oo Se - 4] (2 DTPEL ATE RSE eS i OO Rh ne ga a SE en ergo 92-94 Semen RM PU IU eer Oct 8 2 ee ok ee ee Dees See See eh otek 87-89 aril Cera rse Si ie ee tes oe nS ee ee 87-88 paeaneee rs eee A Sil es Se oer els ae eae ie 88-89 pe meinen ete Se 2 So Paes ee etl EE 49 ee 8 ie ES Sete eee a Se a obs es So 50 Pane Hear Orscnlors, WHE VEINS: / 22.2... 2-2 nc eis ee eee esiiet eee 59-61 Dees De Ses a ae ie ee merrier 32 0 EL SST 2 ay 5 Re eae et eee 50 ne DeNPRENE Wee rie ey Cr SE 2 3 es ew a =o. Lae ee re Se 14 Siete Rewrie a he te Se es oo SE 2 PSS LSS Se hake 19 mnprmresrumare: Loney bees +52: =. 20 os goss Vee ee le 58s 55 MME PMMA ae a A es Boe eee ee oo sos Se a See 19 PiemneremeeEE DIONE Y DCs. 2 0222. yl 2 esos g et ee 55 ELLE EES ELT 2) le gee en ee ee ne ee ee 17 Ie te rk rege oe 8k ia gd 2 SOO edn oes eS Sd ee ee 75 farts eee aS) oe SOR oe at ee eee eee ee 75 | emer ers ete hay ee Sk ee Se oe a ee ee 75 eS eR Ue erie ee ee ey Oa i era ee 75 I ee tte TN oe a os oe ele Sh De oe ee 27, 130 0 EEE RINT 27 Speen’ 2 Sige ta aa ear ey oe 107 PeLmecieormis sts; 2bnonunal segment. -..--.- +... ---2--2-2- se nee---ces 58 > - TUNE cr no Fo 02 ep ey Le ee. Bed VS 57 | COREE ST ELIT ee eipecre te DO aera ey Opry ek aoe Rll Noa og 60-62 ENNIS idee eS a ele 90° ; EDULE EE PSS Se eee ee Opie RTE NEC GR ie ie eget ee ED 105 IG EEO EMR se So eke a oe es eee eS: 33-39 / 160 THE ANATOMY OF THE HONEY BEE. : Page Somites, defined... -.. s: 284 22.2 F428 to ee 12 Spermatheea, defined -< 2.2. (225.05 2. a ee ee 134-135 ptructure in queen.c25 95.02 See a, 136-137 Spermatozoa, defined .....2.2. 22.5 sc eee oe 130 of honeybee: =. sa as eee f captrS oan Se Aes eee ee 134, 137-138 Sperm pump of spermathees.... 220022 ga. 22 5 ee ee re 136-138 spiracles, defined 2.2.28) 4.22 5. 22 oes A 26; 13 or. honey bee. ¢. cvs sea oe ae ee 115-116 piernal laterale, defined 2: .. F< 2.222 S222 ka eee 21 prernellum, denied... 2.252.524.0242. ata oe ee 21 Srermiutes, defined. 2% 00.85i 25) So ae ee ee ee 14 sternum, defined . 22422 .20.bes3 ee oes ee ey ee ee 14 of generalized Insect: