. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CATCH IN SEA URCHIN SPINES 121. Figure 1. The spine-test articulation of Eucidaris. In this Chlorox- digested preparation a small area ofligament remains, maintaining the ball-and-socket arrangement. • 18 defied contemporary evidence, because the latter tissue had been studied by 19th century microscopists (Prouho. 1887; Hamann, 1887) and was recognized by them as being primarily a connective tissue. Takahaslu's mutable connective tissue The problem of catch in echinoderm spines was studied again in the 1960s by Takahashi (1
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CATCH IN SEA URCHIN SPINES 121. Figure 1. The spine-test articulation of Eucidaris. In this Chlorox- digested preparation a small area ofligament remains, maintaining the ball-and-socket arrangement. • 18 defied contemporary evidence, because the latter tissue had been studied by 19th century microscopists (Prouho. 1887; Hamann, 1887) and was recognized by them as being primarily a connective tissue. Takahaslu's mutable connective tissue The problem of catch in echinoderm spines was studied again in the 1960s by Takahashi (1966, 1967a, b, c), who confirmed von Uexkiill's results while disagreeing with him on the nature of the ligament. In the discussion of his landmark paper (1967b) on "Responses to stimuli," Takahashi gave an account of the experimental results that led him to propose a new hypothesis to explain catch. Because at that time the ligament was still regarded as a muscle, Takahashi first attempted to record its contrac- tion following the application of chemical or electrical stimuli. He was not successful. Yet Takahashi was greatly impressed by the effects of the same chemical stimuli on the rate of elongation of ligaments subjected to a constant load (isotonic recording; creep test). In his words "the effects were clear, sometimes even dramatic, and they varied according to the kind of drug ; Lengthening was retarded by acetylcholine. while adrenaline exerted an accelerating effect. These observations led Takahashi to seek the identity of the structural element responsible for the ligament ex- tension under constant load, and he saw a plausible can- didate in the collagen. He accounted for his results on the premise that the mechanical consistency of collagen can switch reversibly between two extreme conditions or states: one pliant and extensible and the other stiff and inextensible. This hypothesis was attractive because it ex- plained a variety of ex
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
