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At its posterior end are given off five long slender processes, the Malpighian tubules which are organs of excretion, acting like the kidneys of higher animals. The hindgut is that portion of the intestine from the stomach to the end of the body. Anopheles at left. Lying under the alimentary canal in the forward part of the thorax are the salivary glands.
These lie parallel in the medullary or central structure, but On reaching the cortical or outer layer, they wind about and interlace, ending, at last, in dilated closed sacs called Malpighian capsules. Vertical Section of the Kidney. Function of the Kidneys. The Malpighian capsules are really the beginning of the tubules, for here the work of excretion begins.
Of course the subject of automatism might have been discussed at far greater length than is allowable in the limits of two magazine articles, but sufficient has probably been said to show the strong current of modern physiological psychology toward proving that all ordinary mental actions, except the exercise of the conscious will, are purely physical, produced by an instrument which works in a method not different from that in which the glands of the mouth secrete saliva and the tubules of the stomach gastric juice.
In the kidney also, repair mainly takes place by cicatricial tissue, and although a few collecting tubules may be reformed, no regeneration of secreting tissue takes place.
The work of Steinach, a Viennese investigator, has contributed most to the elucidation of the nonarterial factor in senility. No one has asserted more loudly the importance of the interstitial cells that fill in the spaces between the tubules of the testes in the male, and the follicles of the ovary in females.
A tumor of the lung would mean death ... but the technique of grafting a culture-grown lung segment to a portion of natural lung required enormous surgical skill, and the finest microscopic instruments that could be made in order to suture together the tiny capillary walls and air tubules. And if one lung were destroyed, a Moruan had no other to take its place.
Masculising of females was much more difficult than feminising of males because the testicular tissue was less resistent, and could not be grafted so easily. When it succeeded, however, degeneration of the seminal tubules took place, with increase of the interstitial or Leydig's cells. The vaginal opening in rats disappeared, partly or completely.
The pelvis is surrounded by reddish cones, about twelve in number, projecting into it, called the pyramids of Malpighi. The apices of these cones, known as the papillæ, are crowded with minute openings, the mouths of the uriniferous tubules, which form the substance of the kidney.
On post-mortem examination the lesions found in these cases are: general hyperæmia of all the organs of the abdominal, thoracic, and cerebro-spinal cavities; marked leucocytosis, with destruction of red corpuscles, setting free hæmoglobin which lodges in the epithelial cells of the tubules of the kidneys; minute thrombi and extravasations throughout the tissues of the body; degeneration of the ganglion cells of the solar plexus; œdema and degeneration of the lymphoid tissue throughout the body; cloudy swelling of the liver and kidneys, and softening and enlargement of the spleen.
Steinach has been studying the interstitial cells that fill in the spaces between the tubules of the testes, in males, and between the follicles of the ovaries in females. His reason for choosing these cells for his experiments is that they are a well-spring of life.
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