Warm Objects Research Articles

Perception experiments in a study of ambivalence.

This investigation is concerned with the perception aspects of a larger study on the problem of ambivalence. The over-all goal in the total project is to find specific etiological factors which can be correlated with success or failure in the resolution of ambivalence. These etiological factors deal with the character of the object relations in early life, the opportunities for object relations in general, and, more specifically, the opportunities for warm object relations. Against these etiological factors a set of measurements of the resolution of ambivalence is being worked out. Two of these measurements are presented in this study. One measurement is a structured interview in which we classify our subject material according to degrees of organization or failure in the handling of impulses. The other measurement is a tachistoscopic perceptual test, a measurement of the accuracy of perception and also measurement of the range and breadth of subsequent visual

Observations on the sensory Physiology and Behaviour of larvae of the cattle tick, Boophilus Microplus (Can.) (Ixodidae).

In larval cattle ticks the main sense organs which have been recognized are the eyes, Haller's organs, and the palpal organs; the four pairs of sensilla sagittiformia may also have a sensory function. Larvae were allowed to ascend supports simulating grass stalks and were tested for response to vibration, air currents, interrupted illumination, warm and moist objects, and odours from skin secretions of man and cattle. The strongest questing response was to the odours. Larvae which had been exposed to low humidities collected around and imbibed from drops of water. The main stimulus governing ascent of the grass blades appeared to be positive phototaxis to moderate light intensities. Larvae sheltered from direct sunlight. Larvae in the field were found to be more exposed in the early morning, often being at the tops of grass stalks. Measurements of light, air temperature, and humidity indicated that light intensity might govern this movement. This suggests that larval sampling in the pasture should take place in the first half of the morning. In a single series of observations, larvae which had hatched at the base of straws were observed to ascend them in the late afternoon. In a few experiments isolated larvae ascended artificial supports above the reach of a bovine host but groups were always found at heights within reach.

Studies of the Responses of the FemaleAëdesMosquito. Part III. The Response ofAëdes aegypti(L.) to a Warm Body and its Radiation

1. A warm object is more attractive to the female yellow-fever mosquito than a cooler object, such that the numbers touching a ball warmed to 100° or 110°F. were twice as great as those touching a ball 20°F. cooler. This attractiveness was reversed when the temperature of the warmer ball reached 120°F.2. This response is eliminated by the insertion of an air-tight window of thallium bromoiodide, despite the fact that it allows almost all of the radiation to filter through. It is therefore concluded that heat convection, which is eliminated by the air-tight window, is the factor which makes a warm object attractive to the mosquito.3. The several faces of a warm cube, differing in their radiant emissivity but identical as to surface temperature, exhibited attractancies toAëdeswhich were not significantly different one from another (except in the case of black enamel, which will be explained in a later paper). These results may be interpreted to indicate that radiation plays no part in the attraction of the mosquitos to the warm face.4. It is concluded that the failure of Parker (1948) to obtain a positive response ofAëdesmosquitos to a warm dry object was due to the fact that his apparatus allowed only the radiant heat but not the convective heat to reach the insects.5 Since the response ofAëdes aegyptito heat is eliminated by a window transparent to infra-red radiation, the theory of olfaction proposed by Beck and Miles (1947) evidently has no application to this species of mosquito.

Host Selection and Cannibalism in the Bed Bug Cimex Lectularius L.

In a paper on the tropisms of the bed bug the author (1930), stated that the heat is the only stimulus which attracts the bug to its host—man. Furthermore, he found that every warm object calls forth such reactions, and that these reactions depend upon the difference between the temperature of the object and that of the immediate environment of the bed bug. If this is true, one would expect that any warm-blooded animal would equally attract this creature, and that it would readily feed upon any host without discrimination. The discussions in the literature dealing with this subject tend to support this view for we find long lists of animals and birds upon which the bed bugs have been found feeding. According to Martini (1923), the following hosts have been recorded: Mamalia: Bat, cat, calf, dog, guina pig, hare, mouse, rat, monkey and rabbit. Aves: Duck, goose, hen, pigeon, sparrow, starling and swallow. Several authors believe, however, that these animals or birds are attacked only in emergency—when human blood is not obtainable, and should a human being be available, the, bugs would attack man rather than animal. If this assumption is correct, the theory advanced in the beginning regarding thermotropism is false—for then one would expect that some other stimulus present in man and lacking in other animals is the alluring agent. In an attempt to throw light upon this subject the author made a study, the results of which are given herewith: