Blood Sporozoans from East African Amphibia*

SYNOPSIS. Haemogregarines are described from the peripheral blood and in some instances from internal organs of 4 species of frogs from East Africa. The parasites from Hyperolius puncticulatus and from Rana wittei have not been reported previously. The haemogregarine from R. mascareniensis is possibly a young stage of a form previously inadequately described. R. angolensis was parasitized by Haemogregarina theileri and also by an organism of uncertain affinity found mainly in the lung capillaries.     

Blood Parasites of Some Reptiles of the Pacific Northwest

SYNOPSIS. Three hundred and fifty-seven reptiles belonging to 15 species (11 genera, 7 families) from the Pacific Northwest were examined for haematozoa. Twenty-six (7.3%) had parasites. Eleven (3.1%) were infected with haemogregarines, 6 (1.7%) with microfilariae and 9 (2.5%) with unidentified organisms. Four species of snakes and 4 of lizards were positive. Several forms of haemogregarine from the Pacific gopher snake ( Pituophis melanoleucus catenifer ) are described.     

Ultrastructural Study of Promastigotes of Leishmania from Reptiles*

SYNOPSIS. The ultrastructure of promastigotes of 4 reptilian isolates of Leishmania grown in culture, is described. One mammalian isolate of Leishmania is also examined for comparison. No differences in the basic ultrastructure of these strains are apparent; neither is there any significant digression from the organization described for other trypanosomatids. It appears, however, that the numbers of subpellicular microtubules are of potential use in taxonomy, and that differences in the spacing of these organelles exist between reptilian and mammalian forms. In addition, an attempt is made to clarify aspects of attachment of the flagellum to the subpellicular tubule network, and to the anterior face of the kinetoplast. Finally, the formation of multivesiculate bodies from the Golgi apparatus is described, together with some features of dividing forms.     

Red cell blood groups of East African Zebu cattle*

A total of 146 East African Zebu, 41 Zebu-Hereford crosses and 24 Ayrshire-Norwegian Red Cattle crosses have been investigated with cattle red cell reagents characterizing blood factors in eleven systems. With a battery of 36 selected reagents the average number of blood factors in Zebu was 20.1 which differs significantly from the average of 12.5 in the Ayrshire crosses. Factor frequencies for the A, C and S systems and gene frequencies for the F, L, M, Z, R' and T' systems are presented. The B system factors in four Zebu bulls could be grouped into eight different phenogroups by utilizing the blood types of dam-offspring pairs.     

Blood Oxygen Transport and Delivery in Reptiles

Cenozoic reptiles are characterized by physiological morphologicaland ecological systems with low energy requirements comparedto those of mammals. Ectothermy and low resting rates of metabolismare the primary physiological adaptations of reptiles that producelow energy demand. Adjustments of the oxygen-transport systemto different thermoregulatory characteristics among reptilesmay be reflected in blood viscosity oxygen capacity oxygen affinityand the temperature sensitivity of oxygenation. Other adaptationsreduce the energy cost of oxygen transport. Reptiles have lowhematocrits and large, widely spaced capillaries that contributeto a low fluid resistance in the vascular system but also limitthe oxygen transport capacity. The low oxygen affinity characteristicof the blood of most reptiles appears to facilitate diffusionof oxygen to the tissues, overcoming the intrinsic limitationsimposed by the morphological specializations of the cardiovascularsystem. The low blood oxygen affinity permits virtually allof the oxygen carried by the blood to be delivered to the tissuesduring periods of stress. It may also help to maintain a relativelyhigh arterial Po₂ even when a right-to-left shunt occurs inthe heart. Reptilian erythrocytes are capable of reducing methemoglobinrapidly. The high concentrations of methemoglobin and polymerizedhemoglobin that occur in vivo may indicate that these compoundshave a functional role. In their blood physiology as in otheraspects of their biology reptiles are specialized animals thatreflect selective forces quite different from those that haveshaped the evolution of mammals.     

East African Politics

The Culture of Politics in Modern Kenya. Angelique Haugerud
Networks of Dissolution: Somalia Undone. Anna Simons