But many lower organisms, especially insects, regard chickens with reverential fear. The classification schemes of the three taxonomists serve to define the position of the Geophilomorpha and will be of historical as well as systematic importance. With the exception of the front and rear limbs of the animal, the body is a repetition of almost identical segments.
There is a single elongate testis in the male and paired seminal vesicles, which communicate into the single genital opening located ventrally on the penultimate segment. In the higher insects the ganglia of adjacent segments are so concentrated that they cannot be distinguished as individual entities. Since sensory neurons are located in the epidermis, the neurons involved in the central nervous system are either motor or interneuronal in nature and are usually unipolar.
There is no correlation between the inability to see with a qualitative hypoplasia of the central nervous system. The subesophageal ganglion communicates with the supraesophageal ganglion through the circumesophageal junctions, which surround the esophagus.
ACKNOWLEDGMENTS
REVIEW OF THE LITERATURE
I40tem establishes a connection with the stomatogastric or "sympathetic", this establishes a connection with the stomatogastric or "sympathetic".
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 7
The main ganglia and nerves of Lithobiisforficatus, Scolopendra cingidata and the geophilomorph from Japan, Scolioplanes® hirsutipes, were described and clearly illustrated. Since the current study concerns the geophilic Arenophilus bipuncticeps (Wood), a brief summary of the taxonomy of this organism is provided. Crabill (1955) collected specimens of this species from three Missouri counties and eight sites in and around St.
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 9
MATERIAL AND METHODS
HISTOLOGICAL PROCEDURE
10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 in a plastic funnel placed above the microtome blade and object carrier
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO II
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 Hansen's iron trioxyhematein
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO I3
RECONSTRUCTION TECHNIQUES
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40
OBSERVATIONS
GROSS ANATOMY OF THE CEPHALIC NERVOUS SYSTEM The cephalic nervous system of hipuncticeps is a small mass di-
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO
NNIM
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 17 posterior ganglion is more ventrally situated than the anterior one
4 THE CENTIPEDE NERVOUS SYSTEM — LORENZO 17posterior ganglion is more ventral than the anterior. It is located at the point where the imaginary transverse and sagittal midlines intersect on the dorsum of the cephalic plate (Figure i). Conventionally (according to the terminology of Viallanes, 1887), the supraesophageal ganglion is divided into three parts: protocerebrum, deutocerebrum, and tritocerebrum.
As these neuromeres are fused into a single mass in the brain of bipitncticeps, it is impossible to delineate their extent in whole mounts. In centipedes with well-developed eyes, i.e. Scutigeromorpha and some of the Lithobiomorpha, this region is large and clearly demarcated from the underlying deutocerebrum and tritocerebrum (Fig. 4, A and B). The term "protocerebrum" will nevertheless be used to refer to the posterodorsal part of the brain.
The two antennal lobes are clearly separated in the brains of the other orders of millipedes (Fig. 4, A, B, C), but in the geophilomorphs they are fused at the midline (Fig. 4, D). The poorly developed tritocerebral lobes begin anteriorly as a fused central mass but diverge at their posterior extensions as continuations of the circumesophageal connections.
CEPHALIC NERVES
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 19
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 to develop a new terminology for the cephalic nerves of bipuncticeps,
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 21
The recurrent nerve dorsal to and runs between the levator pharyngis muscles which insert on the pharynx (pi. These three nerves and a pair of tracheoles emerge simultaneously from the ventral surface and form a "kind of tuft." This expression was used by Saint Remy ( 1887) in the description of the same place in. The recurrent nerve continues caudad for about 100 microns and bends sharply dorsal to the esophagus (fig. 3).
Nerves of the suesophageal ganglion.- Three pairs of nerves arise from the lateroventral aspect of the suesophageal ganglion. The three nerves are sensory to the receptors and motor to the internal muscles of the mouth parts.
HISTOLOGY OF THE CEPHALIC NERVOUS SYSTEM
Neurilemma and neuroglia. — The neurilemma is composed of an
The majority of the cells in the cerebral cortex are association neurons. In certain parts of the brain, especially in the posterior cortex, these cells are so packed that their nuclear membranes appear to touch each other. Typical neurosecretory neurons were not observed in the frontal lobes or in any other part of the supraesophageal ganglion with the stains used.
Neuropile.— The histology of the neuropile is more revealing in the present study than that of the cortex. The three brain neuromeres of bipuncticeps are readily homologized to these entities as they are non-arthropod exposed by a study of the neuropil. The protocerebrum is identifiable by the presence of "frontal lobes". These lobes are weak, lateral projections of the neuropil (pis. 3 and 4).
If it is assumed that the supraesophageal ganglion of this centipede is homologous with that of Thcreuopoda, whose tracts were studied by Fahlander, then some order may be found in the neuropils of the geophilic brain. If one imagines that the ventral part of the brain of the scutigeromorph is moved posteriorly and the dorsal part anteriorly, and the relocated structures. The antennal glomeruli in hipuncticeps do not have the scalloped appearance of the antennal glomeruli in the higher arthro-.
Nevertheless, it is most likely that some fibers cross the opposite side of the small commissure located dorsoposteriorly in the protocerebrum (pi. The first anterior continuity of the neuropil in the median plane occurs in the anterior half of the tritocerebrum. The strongly stained fibers connect the frontal lobes, deutocerebral lobes, and bases of tritocerebral lobes.
The majority of the fibers crossing the greater commissure in the anterior part originate from the lateral part of the frontal lobes (pi). This morphological observation identifies the anterior part of the canal as the “great protocerebral commissure” of other authors. of the circumesophageal connections" is the only radical displacement of commissural elements in the bipuncticeps brain.
DISCUSSION THE GANGLIA
4 NERVOUS SYSTEM OF A HIGH SPOT — LORENZO 29 with about 90 microanterior to the caudal of the brain, crossing about 90 microanterior to the caudal of the brain, this transverse fillet extends almost to the posterior border of the ganglion. This large commissure is obviously the most important association area in the brain of bipuncticeps. Although connections with fibers originating from the three neuromeres are made at each level, there is a pattern that can be resolved by the postulated shift of commissures (fig. 5).
The absence of light receptors and of the organ of Tomos results in a reduction in the size and number of neural components in this area of the brain. The majority of the fibers associated with the deutocerebral lobes originate from the sensory neurons in the antennae and association neurons of the cortex. The frontal ganglion and its connections and the stomatogastric ganglion in the Scutigeromorpha are separated and lined with their own neurilemma.
THE CEPHALIC NERVES
In bipuncticeps, these elements are incorporated into the central neural mass in such a way that they are imperceptible. Motor fibers were identified in N7 and traced to the same nucleus of origin as the fibers of N9 and Nn, and then to the extrinsic antennal musculature. Fahlander may have confused the fibers of one of the intrinsic motor nerves with those of.
Saint Remy (1887) could not demonstrate it in Necrophloeophagus longicornis and said that its absence was well explained by the concentration of the tritocerebral ganglion. Fahlander admitted that he found no continuity between the N20 on one side and that on the opposite side, but he still had "no doubt that the Geophilomorpha correspond in this respect to the other genera of juveniles." His effort to homologize the four orders of centipedes prevented him from admitting that the free tritocerebral commissure he showed in the other three orders might not be present in geophilomorphs. It is customary to consider a dorsal motor and a ventral sensory root in a typical arthropod ganglion (Wigglesworth, 1953).
Experimental studies of nerve degeneration and chromatolysis such as those performed by Vowles (1955) would probably indicate that the ventral surface of the subesophageal ganglion is a motor area. The nerves innervating the mouthparts of hipuncticeps arise from the subesophageal ganglion and generally agree with the arrangement in Strigamia hirsutipes.
32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 CELL TYPES
NERVE TRACTS
THE FAHLANDER-FERRIS CONTROVERSY
This concept is the starting point from which Henry undertook the study of "Nervous System and Segmentation in Annulata," which appeared under that title in five articles. She interpreted the segmentation of the chilopod head and the extension of the cephalic nerves in the light of her investigations into the nervous systems of Polychaeta, Onychophora and Crustacea. Applegarth (1952) continued the program with a study of the cephalic musculature and innervation of the same lithobiomorph.
A comparison of the various controversial areas revealed the following discrepancies: i) Fahlander described a short, thin motor nerve (ug) that innervates and originates from part of the levator pharyngis muscle.
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 Ferris failed to emphasize that Fahlander was describing the nerve
It becomes immediately clear to one who has studied both articles that the interpretation given by Ferris to Fahlander's descriptions does not seem to be accurate. On the contrary, the reliability of Fahlander's work has been strengthened by the study of the points of disagreement revealed by his antagonist.
CONCLUDING COMMENTS
SUMMARY
The cephalic nerves arise from the three neuromeres of the brain and the subesophageal ganglion and are homologous to those of other chilopods. The nerves supplying the intrinsic and extrinsic musculature of the antennae were traced to their nuclei of origin located ventrally in the deutocerebrum.
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 37 emerges from a stomatogastric bridge which is poorly developed and
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 Hess, A
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 4I
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 140
EXPLANATION OF PLATES
NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 43 Plate 5
