SYSTEMATICS OF ISOPTERA FROM CHINA——2. DESCRIPTIONS OF THREE NEW SPECIES OF TERMITIDAE

The present paper deals with 3 new "Capritermes typus" termites belonging toMirocapritermes, Procapritermes and Homallotermes respectively. Holotypes, morphotypes,paratypes and thier duplications are deposited in Huanan Tropical Crops College, Tan-hsien, Hainan Is., China.     

I. THE EXPRESSION OF INSTABILITY IN N. TABACUM × N. PLUMBAGINIFOLIA

Moav , Rom (Hebrew U., Jerusalem), and D. R. Cameron . Genetic instability in Nicotiana hybrids. I. The expression of instability in N. tabacum × N. plumbaginifolia. Amer. Jour. Bot. 47(2): 87—93. 1960.—N. tabacum (n = 24) and N. plumbaginifolia (n=10) are distantly related species both from morphological and cytological points of view. Hybrids of these species with various genome dosages have exhibited somatic variegation when plumbaginifolia dominant characters were superimposed on an appropriate tabacum genetic background. Five loci were studied in this respect: Wh and Tg—for flower coloration; Ws—for chlorophyll production; Kl—for pollen abortion and Bs—for black shank resistance. All 5 were found to be unstable. Backcross progenies of the sesquidiploid hybrid (tbc-tbc-pbg) to tabacum showed a marked increase in intensity of variegation. This has been attributed to the breaking up of the plumbaginifolia genome into individual chromosomes. The evidence indicates that variegation was due to somatic chromosomal aberrations which probably characterized all the plumbaginifolia chromosomes. An hypothesis regarding the heterogeneity of F₁ hybrids of distantly related homozygous species is outlined and the occurrence of instability due to hybridization in other Nicotiana hybrids is discussed.     

CYTOGENETIC STUDIES ON THE ORIGIN OF TAGETES PATULA. I. MEIOSIS AND MORPHOLOGY OF DIPLOID AND ALLOTETRAPLOID T. ERECTA × T. TENUIFOLIA

Towner , Joseph W. (U. California, Los Angeles.) Cytogenetic studies on the origin of Tagetes patula. I. Meiosis and morphology of diploid and allotetraploid T. erecta × T. tenuifolia. Amer. Jour. Bot. 48 (9): 743–751. Illus. 1961.—Cytological and morphological evidence is presented to show that Tagetes patula L. is an allotetraploid species (2n = 48) which probably originated by hybridization between the diploids T. erecta L. and T. tenuifolia Cav., or species closely related to them. The putative parent species are separated by strong reproductive isolation barriers, and controlled crosses between them yielded very few good seed. Most of the hybrid seedlings died before reproductive age, and the few survivors were sterile and extremely weak. At meiosis in the diploid hybrid, bivalent frequency per cell was 0–11 and averaged 4.4. Although 43.6% of the quartet stage consisted of restitution dyads, pollen was essentially all non-viable and seed set was less than 1%. A true-breeding, fertile, allotetraploid T. erecta-tenuifolia was synthesized by colchicine-doubling of the chromosome number of the F₁ hybrid. In the synthetic allotetraploid, average chromosomal association was 23.97 bivalents plus 0.05 univalents, and 97.4% of MI cells had 24 bivalents; there were no multivalents, bridges, or fragments. Tagetes erecta-tenuifolia showed a striking morphological similarity to T. patula. Both the natural and synthetic allotetraploids were intermediate between T. erecta and T. tenuifolia for nearly every character. Of 10 species of Tagetes whose chromosome numbers are known, 5 are tetraploid (2n = 48).     

THE RHEOLOGY OF THE BLOOD : IV. THE FLUIDITY OF WHOLE BLOOD AT 37°C.

In the preceding paper (1b) a formula was developed for the lowering of the fluidity of a medium by a mixture of proteins, given the volume concentration of each and its fluidity-lowering constant. Whole blood is now shown to follow an essentially similar formula, except that the hemoglobin content is taken from the literature as the best available measure of the volume of the blood cells Δ Φ = 0.24H, assuming the fluidity of the medium to be 53 rhes. Age, sex, diet, barometric pressure affect the hemoglobin content of the blood, but the formula may apply to any healthy human blood to about 3 per cent. The shape, number, and size of the blood cells, if known, might help to explain discrepancies as well as the state of oxidation of the blood. In disease the discrepancy becomes much greater, suggesting the possible use of rheology in diagnosis.     

METAMORPHOSIS OF THE LARVA OF THE POLYCHAETE ARENICOLA CRISTATA. MORPHOLOGY OF THE ‘HOUR-GLASS’ STAGE

The constricted ‘waist’ of the metamorphosing larva of the polychaete Arenicola cristata is described, using light and electron microscopy. The constriction is shown to be the consequence of the discharge and collapse of a post-trochal ring of epithelial cells which remain as functional components of the post-metamorphic juvenile. Morphological differentiation of neuro-effector and interneuronal contacts is initiated at this time. Muscular and neural changes are discussed in terms of their role in effecting metamorphosis.