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This study assessed the effects of variation in the relative spatial orientation of figures on tactual pattern recognition. Metric figures at two levels of complexity, 4 × 4 and 6 × 6, were used. Ss were required to determine which of two choice figures was identical to a previously presented target (identity indicator response) or, if neither of the two choice figures was identical to the target (non-identity indicator response). Two orientation conditions were employed: (1) all figures were oriented in the same direction and (2) choice figures were oriented in different directions relative to the target and to each other. In general, differential orientation degraded both the accuracy and speed of recognition. The negative effects of differential orientation were dependent upon figure complexity and the type of indicator response when perceptual performance was measured in terms of accuracy but not when a speed index was used. Patterns at the low level of complexity were recognized more rapidly than high complexity patterns when a non-identity indicator response was required; no differences between complexity levels were noted with the identity indicator response.

A chymotryptic-like fragment of the rat proinsulin connecting peptide (C-peptide) has been isolated from whole rat pancreas. Amino acid analysis and partial sequence determination showed the fragment to contain the NH2-terminal 22 residues of C-peptide I. A radioactive fragment of similar electrophoretic mobility was also isolated from rat pancreatic islets which had been incubated with [3H]-leucine. Stepwise Edman degradation of the radioactive fragment showed the positions of its leucine residues to be identical with those of the unlabeled material. Homogenization of [3H]leucine-labeled rat C-peptide with whole pancreas and extraction under conditions used for the isolation of the fragment did not result in cleavage of the C-peptide to the fragment. Furthermore, the fractional ratio of fragment to C-peptide (normally about 0.2) did not increase when rat islets were incubated with [3H]leucine for 1 hour and then incubated with unlabeled leucine for 1, 2, or 3 hours. Treatment of a mixture of [3H]leucine-labeled proinsulin and proinsulin intermediates with high amounts of trypsin resulted in the release of the C-peptide fragment as well as desglutamine (residue 31) C-peptide. It is concluded that a chymotrypsin-like cleavage in the C-peptide region of proinsulin or in one of its intermediates occurs normally during the conversion of proinsulin to insulin in the rat.

Experimental approaches for selecting hormone-dependent cells, hybrid cells, and haploid cells are discussed. Experiments are described for isolating mammary tumour cells which are dependent on the presence of prolactin and insulin for growth.

An advertisement for the writing talent test devised by Palmer Writers School is presented.