Direct Passages Research Articles

Letter from a Young Blind Man

[Do schools and organizations serving blind people become too casual at times in the execution of their programs? Do they, under pressure of harrying demands on the time of administrators and staff, become production-minded at the expense of individual attention to the practical and direct solving of the individual needs? Is it somebody else's function to solve what is apparently lacking in guidance preparation of the young man whose letter appears below, for life after school? Is everybody's responsibility fully discharged at a point where he is left to find out for himself by chance and by a gift of an inquiring mind what further aids, what more advanced opportunities are available to him? Is it ethical, is it productive of improved professional standards, is it a service to the blind client, to disparage the work of another organization engaged in his behalf? Do you know how frequently letters come from blind individuals whose underlying message, conveyed in direct passages or “between the lines” is a conscious or subconscious groping for help? This one was addressed to Charles G. Ritter. Consultant, Aids and Appliances. American Foundation for the Blind. Names and passages indicating identity of the writer are deleted.—Editor]

Studies on Streptococcus Agalactiae Infection: I.—Infection of the Chick-Embryo and Mouse

A strain of Str. agalactiae was carried through 37 direct passages in the chick-embryo, and 33 in the mouse. The nature of the infection in these hosts is described and compared with infection by Group A streptococci. The virulence of various strains of Str. agalactiae and of Group A streptococci was compared in the chick-embryo and mouse. There was no correlation between virulence for these two hosts.

Studies on the behaviour of Trypanosoma evansi in tsetse-flies with special reference to its phylogeny

In view of the morphological similarity of T. evansi and T. brucei, including the sporadic occurrence of marked polymorphism in the first-named species, the hypothesis is advanced that T. evansi may have originated from T. brucei, by the introduction of the last-named species into localities free of Glossina and its subsequent propagation by direct passages.The possibility of contact between the mammalian host of T. evansi, on the one hand, and Glossina and tsetse-borne trypanosomiases, on the other, is shown to exist in the Anglo-Egyptian Sudan, thus pointing to the source from which T. evansi in that country may have originated and providing circumstantial evidence in support of the hypothesis.Attempts were made to discover whether T. evansi is capable of developing in Glossina. A total of 568 flies were fed on infected mice and examined at periods from 6 hr. to a fortnight following the infective feed. The results were entirely negative: not only is the trypanosome incapable of establishing an infection in the fly, but the majority of flagellates perish and are digested during the first hours after ingestion by the insect.The behaviour of T. evansi in tsetse is shown to be similar to that of non-transmissible strains of trypanosomes of the Brucei group after prolonged maintenance by direct passages in the mammalian hosts, and is therefore also in keeping with the hypothesis.

The Relationship between Topography and Geology

Abstract Topography is an expression, by means of physical features, not only of the geology of a country, but to a very large extent of its geological history. So much is this so that if on a map the geology and topography do not fit snugly together either one or the other is wrongly mapped. Streams owe their early existence to uplift and tilting of the stratified rocks. They run down the slopes as off the roof of a house and cut their way to the sea, selecting carefully the easiest channels. Runnels are soon made in the softer rocks, and when harder ones present themselves a way round can usually be found if no break or gap can be seized upon for more direct passages. On the surface of the earth there would be no relief but for uplift, folding and fracturing of the strata. Relief so formed would be short-lived but for the fact that the rocks vary greatly in hardness and resistance to the action of the elements. Wind, rain, alternations of heat and cold, the work of running water, the fretting of the tides, all tend to plane down what is uplifted above sea level and to reduce everything to uniform plain.

THE TRANSMISSION OF YELLOW FEVER

1. Saimiri sciureus has been infected with yellow fever virus, both by the inoculation of infectious blood and by the bites of infective mosquitoes. Some of the monkeys have died, showing lesions, including hepatic necrosis, suggesting yellow fever as seen in human beings and in rhesus monkeys. Virus has been transferred back to M. rhesus from infected Saimiri both by blood inoculation and by mosquito bites. The virus undoubtedly has been maintained through four direct passages in Saimiri. Reinoculations of infectious material into recovered monkeys have not given rise to invasion of the blood stream by virus. Sera from recovered animals have protected M. rhesus against the inoculation of virus. 2. It has been possible to pass the virus to and from Ateleus ater by the injection of blood or liver and by the bites of mosquitoes. The livers from two infected animals have shown no necrosis. The serum from one recovered monkey proved to be protective for M. rhesus. 3. Only three out of twelve Lagothrix lagotricha have reacted to yellow fever virus by a rise in temperature. Probably none have died as a result of the infection. In only one instance has the virus been transferred back to M. rhesus. The sera of recovered animals have had a protective action against yellow fever virus.