MICROTUBULES IN THE SPERMATIDS OF THE DOMESTIC FOWL

Spermiogenesis in chicken has been examined in order to see whether the radical changes observed in cell shape can be related to the presence of cytoplasmic microtubules. A highly ordered array of tubules has been found which surrounds the nucleus as it elongates from a sphere to a slender cylinder. The structure of the array has been determined by following the tubules through 12–14 adjacent serial sections, and it is a left-handed double helix. Faint cross-bridges connect consecutive turns of the two helices. After the change in nuclear shape is complete, the helical system of microtubules disappears and is replaced by a set of almost straight tubules which run parallel to the long axis of the nucleus. These tubules remain while the spermatid nucleus condenses isotropically to its final size. We suggest that the helix is the agent which effects nuclear elongation and that the subsequent system of paraxial tubules determines the curvature of the final sperm head. Evidence for these suggestions is found in the form of spermatids which have failed to develop properly. In an appendix we consider the kinematics of single and multiple helix systems and discuss the revelance of these models to the morphogenesis of chicken spermatids.     

THE ACTIVITY OF PERIPHERALLY STORED NEUROHUMORS IN CATFISHES

1. Adrenalin when mixed with olive oil 1:100 and injected subcutaneously into a catfish will produce a marked pale spot and a general blanching of the whole fish. The general blanching will disappear in about a day. The pale spot may last 3 to 4 weeks. 2. Injections of adrenalin in oil 1:1000 to 1:10,000,000 cause the formation of only pale spots in catfishes. Adrenalin in oil 1:100,000,000 has no effect on the fish''s color. 3. Acetylcholine, though ordinarily more powerful than adrenalin, when mixed with oil is effective only in high concentrations 1:20 to 1:100. It then produces clusters of moderately dark spots. 4. The pale spot on a catfish due to adrenalin in oil may be temporarily obliterated by intermedin. It will return of itself, and this process may be repeated a number of times. The same is true of the dark spots produced by acetylcholine in oil when subjected to adrenalin. These observations indicate the subcutaneous storage of both adrenalin and acetylcholine in oil. 5. In the natural color changes in catfishes the nervous neurohumors, probably also adrenalin and acetylcholine, appear both to be stored in the fish''s lipoids and to serve thus as a means of lenghthening the times of initial color responses till these stores of neurohumors are exhausted.     

SENSORY PROPERTIES AND CONSUMER PERCEPTION OF 'HOME-MADE'AND COMMERCIAL DAIRY ICE CREAM

Sensory properties and consumer perception of 2 'home-made'and 4 commercial dairy ice creams were examined. Conventional profiling by a trained panel found that most samples differed significantly in all attributes, but distinction of 'home-made'from commercial products was limited to few attributes. Principal component analysis separated the 'home-made'products from the commercial ones mainly on the basis of differences in appearance, aroma, creamy flavors and textural attributes. A consumer group (n=105) recorded preconception of 'home-made'ice cream acceptance, then received the product samples, in unlabeled condition, for assessment of degree of liking (DOL) and for identification as 'home-made'or commercial. Internal preference mapping of the DOL ratings showed that consumers were more closely grouped around samples which had higher intensities of certain attributes. Higher 'denseness', 'vanilla'aroma and 'buttery'flavor, were associated with more liking for commercial products. The 'home-made'high fat sample, although liked, tended to be grouped with commercial products. More marked textural attributes of 'ice crystals'and 'breakage'aided identification of the low-fat 'home-made'formulation, which was less liked overall. Overall, differences between the 'home-made'and commercial samples were small but consumer perception of the term 'home-made'was viewed favorably for dairy ice cream.