It is argued that Tertullian's relatively lengthy description of a chameleon in his De pallio serves as a metaphor not so much for the convert to a philosophical way of life in general but for the convert to Christianity in particular. The argument rests on the unusual emphases within this description which recall different features of Christianity or popular beliefs about the same.

Neurons containing catecholamine, indoleamine, and gamma-aminobutyric acid (GABA) were identified by immunohistochemistry in the chameleon retina. Tyrosine hydroxylase (TH) and serotonin (5HT) were observed mostly in two subtypes of orthotopic amacrine cells differing in their soma size and process distribution within the IPL. Some labelled cells were displaced either to the IPL (5HT) or to the GCL (TH and 5HT). A multiplicity of retinal cell types contained GABA including cones, horizontal, amacrine, and ganglion cells. Our results confirmed those obtained in the retinas of other lizards except for the presence of interstitial and displaced amacrine cells containing TH or 5HT of which this is the first report.

Spontaneous eye movements as well as visual, vestibular, and proprioceptive cervical reflexes which contribute to gaze stabilization were investigated in the chameleon using the magnetic search-coil technique. The oculomotor range of each eye was very large (180 deg horizontally × 80 deg vertically). Spontaneous ocular saccades were independent in the two eyes and could have very large amplitudes. The fast phases of nystagmus during the stabilization reflexes were also independent in the eyes. In the head-restrained condition, optokinetic nystagmus (OKN) had a low gain in both horizontal and vertical planes (0.35 at 5 deg/s) and showed little binocular interaction. The vestibulo-ocular reflex (VOR) exhibited a low gain (0.2–0.3 from 0.05–1 Hz) and a high-phase lead at low frequency (140 deg at 0.05 Hz). Rotation of the animal in the presence of a visible surround increased the overall gain of gaze stabilization to 0.4–0.5 (P < 0.01) and considerably reduced the phase lead (38 deg at 0.05 Hz). In the head-free condition, head and eye reflexes were active simultaneously during both optokinetic and vestibular stimulation, but nystagmic head movements appeared only occasionally with a rather loose eye-head coordination. During optokinetic stimulation, eye movements contributed more than head movements to gaze stabilization, whereas, during vestibular or visuo-vestibular stimulation, the relative contribution of eye and head responses varied with stimulus frequency. When the head was freed, overall gain for gaze stabilization increased from 0.35 to 0.45 (P < 0.05) for optokinetic stimulation at 5 deg/s and from 0.2–0.3 to 0.4–0.75 (P < 0.001) for vestibular stimulation at 0.05–1 Hz. Optimal gaze stabilization (gain of 0.8) was only obtained with combined visual and vestibular stimulation in the free-head condition. Cervical stimulation provoked a compensatory cervico-ocular reflex (COR) with a gain of 0.2–0.4 as well as ocular saccades, which were especially numerous in the presence of a visual surround. The direction of these saccades alternated between compensatory and anti-compensatory.

The cervico-ocular reflex (COR) was investigated in the chameleon. Two kinds of responses were observed by oscillating the body (sine-wave stimuli) in the fixed-head animal: a "smooth response" of very low gain (around 0.08) and a saccadic response composed of 1–12 saccades per cycle of stimulation (depending on the stimulation frequency). Both responses were elicited in the compensatory direction (same direction as the stimulation) and exhibited a frequency dependence with low-pass properties. The saccadic response was especially developed and displayed a higher gain (up to 0.4) than the smooth response. In darkness, the saccades were triggered near the zero point (head-body alignment), whereas in the presence of a fixed visual surround they were elicited more regularly throughout the stimulation cycle. The amplitude of saccades was increased in the light. Consequently, the gain and the phase lag of the saccadic reponse were enhanced by the visual input. No visuo-cervical interaction was observed for the smooth response. Oscillating the body at a constant velocity (seesaw or ramp stimuli) revealed a frequency effect on the number of saccades (during a cycle of stimulation), but not on the gain of the response. Increasing the amplitude of oscillations augmented only very slightly the amplitude of saccades and consequently decreased the gain. Hence, the best working range of the saccadic response corresponds to body or head movements of low amplitude (up to ±20 deg) and low frequency (up to 0.25 Hz), and is improved by a visual input. These properties are discussed on a comparative point of view. It is proposed that, in chameleons, the saccadic response could contribute to gaze stabilization and add to the vestibulo-ocular and the optokinetic responses.

Many of Madagascar's endemic chameleon species have restricted ranges and require relatively intact forest for survival but information on their response to habitat degradation is generally lacking, especially in western deciduous forests. We assessed the abundance and density of endemic chameleons from nocturnal surveys of roosting animals in Parc National Tsingy de Bemaraha in western Madagascar. We found 444 Brookesia brygooi, 192 B. perarmata, 98 B. exarmata, 22 Furcifer nicosiai and two F. cf. petteri. The highest pooled density was for B. brygooi (53.2 ha-1), followed by B. perarmata (29.2 ha-1) and B. exarmata (18.7 ha-1). B. brygooi was ubiquitous, with the highest density and abundance in the disturbed Ankazomanga forest outside the Park, where the similarly sized B. perarmata was absent. B. perarmata, a species endemic to the Park, was abundant in three of the five survey sites, especially where there was a well-developed leaf litter and understorey. B. exarmata, a species endemic to the Bemaraha plateau, was associated with an open understorey and small protrusions of limestone karst. Spatial variation in the density of B. perarmata is an important consideration when interpreting monitoring data and this species is a conservation priority because of its restricted distribution and apparent sensitivity to forest degradation.

We quantified habitat associations and evaluated the conservation status of a recently identified, undescribed species of dwarf chameleon, Bradypodion sp. nov. Dhlinza, endemic to scarp forest remnants in KwaZulu-Natal Province, South Africa. At the microhabitat scale the Dhlinza dwarf chameleon was found more often in forest gaps and near paths than highly disturbed edges or forest interior. Chameleon presence was not explained by forest physiognomic variables such as vine cover, shrub and tree density, or canopy cover. Presence near gaps may be better explained by the combined effects of the thermal microenvironment and food availability. The species is moderately common where it occurs, with estimated densities of 4.7, 8.7 and 29.7 individuals per ha within forest interior, edges and gaps respectively. At the landscape scale, the chameleon occurs only in three remnant forests: the Dhlinza, Entumeni and Ongoye Forests. The species' extent of occurrence was estimated to be 88 km2 and its area of occupancy 49 km2. Based on the small area of remaining suitable habitat, this species meets the requirements for categorization as Endangered according to IUCN Red List criteria.

The chameleon genus Brookesia, with 26 species, is endemic to Madagascar. The main threats to Brookesia are habitat destruction and collection for trade. At the CITES Conference of Parties 12, held in Santiago, Chile in 2002, all but one Brookesia species were added to Appendix II, under which trade is controlled in order to avoid utilization being incompatible with species' survival. The Vulnerable B. perarmata was added to Appendix I, under which trade is permitted only in exceptional circumstances. Summary information for Brookesia is presented here, reviewing taxonomy, habitat preferences, available population estimates, relevant legislation, major threats, and trade levels. Brookesia live on or close to the ground, with roost sites mostly <1 m above ground. Density estimates are available for only a few species, with a mean density estimate for four species across sites and seasons of 16 individuals ha−1. A number of species have distinct altitudinal ranges, and a preference for primary forest. Continued deforestation will therefore potentially lead to extirpations. Research on population sizes and seasonal trends of Brookesia is required, without which, combined with data on the impacts of harvesting, the establishment of sustainable trade will not be possible. The apparent reduction and possible cessation of trade in B. perarmata following its listing on CITES indicates that the Convention can succeed in managing global trade in a threatened species.

Malagasy chameleons are threatened by the relentless pace of habitat destruction. Their great popularity amongst herpetoculturalists has also resulted in collection for international animal markets. Most previous fieldwork has focused on the compilation of much needed species inventories, but little attention has been given to estimating chameleon population densities. This lack of information prevents a reliable assessment of the effects ofhabitat loss and direct exploitation on wild populations. A simple and repeatable methodology for the monitoring of chameleon populations is therefore urgently required. The present study developed survey techniques based on distance sampling within an area of relatively undisturbed rain forest at Ranomafana National Park. In total 394 individuals from six species were recorded and population densities (± SE) of 27.2 ± 5.4/ha Brookesia spp. and 21.4±4.0/ha Calumma spp. were estimated using the computer program DISTANCE. The authors propose that monitoring of chameleons in areas subject to different threats should begin immediately using the methods outlined in this paper.