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The speed of snakes moving by lateral undulation was measured on a smooth board studded with equally spaced pegs arranged in a hexagonal pattern. For some snakes speed was drastically reduced (by as much as 50%) as the ratio of body length to peg spacing was reduced from values as high as twelve to values near or below three. Speed is also influenced by the relative orientation of the pegs contacted by the moving snake. Snakes which can sidewind use this ability to maintain a constant speed when the number of contact points available is insufficient for continuous lateral undulation."

The variance test and log likelihood ratio test are both well known in examining a series of n discrete observations for agreement with an assumed common Poisson distribution. This paper compares the tests in small samples with the corresponding x2 significance levels, and also the small sample power under several Poisson-type alternatives.

If retrieval in short-term memory can be either from a pre-perceptual sensory store or from a post-perceptual memory then recall should vary as a function of input into sensory store. To test this possibility two experiments with paired associates compared visual and auditory presentation under conditions as comparable as possible. In both experiments modality interacted with retention interval: more recency with auditory but, in Experiment I, more primacy with visual. The interaction was taken as support for the hypothesis. An alternative hypothesis (that storage is post-perceptual but not a-historical) was discussed and weak negative evidence presented.

1. The removal of the thyroid gland prevents metamorphosis in amphibians.

Current views on causation of sexual perversion.An alternative to these, based on the relationship of the pervert with others, is put forward.Sexual perversions and psychoneuroses are not positive and negative aspects of infantile sexual components.Verbatim extracts from the analysis of a patient with sexual perversion are given to illustrate and support the following views: (a) The emotional relationship between the pervert and others is an essential element in the condition. (b) The physical aspects of the perversion are of secondary importance to the mental. (c) The perversion indicates a failure in personal and social integration; and an effort is made to alter this by means of aggressiveness, adopted child-like conduct, and perversions. (d) The perversions were manifold in type but uniform in purpose. (e) The policy of the illness was to regain a satisfying personal and social life. (f) The same policy is found in the psychoneuroses.

This article describes the state of knowledge about insect sound production and hearing with special reference to Drosophila and some larger insects.

This paper deals with the problem of the interpretation of response latencies in short-term memory. A paired-associate study using a probe technique was conducted with the main experimental variation the length of the recall interval (1, 2, or 4 sec.). While shortening the interval had a statistically significant effect on recall probability the interaction between recall interval and probe position was negligible. While traditionally response latency is considered a measure of associative strength, such an interpretation seems inappropriate here. As an alternative, latencies may reflect more criterion values than sensitivity as these measures are interpreted in signal-detection theory.

1. Gamma irradiation doses of 10,000 r, 20,000 r, 30,000 r and 60,000 r were given to recently metamorphosed Bufo boreas halophilus. Toads receiving the two lower dosages were killed at the end of twenty-four hours and at six days. Those receiving the two higher dosages were all killed at twenty-four hours. Cell destruction was found in the inner nuclear and ganglionic layer of the retina but none was found in the outer nuclear layer nor in the rods and cones.2. Destruction increased as the dosage increased. At doses of 10,000 r and 20,000 r, pyknotic nuclei were most abundant near the marginal portion of the retina, where the cells had been formed more recently than in the central portion. In animals that were given 60,000 r, pyknosis of retinal nerve cells was general and almost complete.3. Divided daily doses of 10,000 r given six times, 20,000 r three times, and 30,000 r two times produced as much destruction as a single dose of 60,000 r. The amount of edema in these cases was never as great as that which was caused by a single dose of 60,000 r.4. At the ora serrata where structural differentiation was not yet evident, cells interpreted as prospective nerve cells were destroyed while there was no destruction of prospective sensory cells of the outer nuclear layer.