August Krogh — Danish Scientist born on November 15, 1874, died on September 13, 1949

Schack August Steenberg Krogh ForMemRS was a Danish professor at the department of zoophysiology at the University of Copenhagen from 1916-1945. He contributed a number of fundamental discoveries within several fields of physiology, and is famous for developing the Krogh Principle... (wikipedia)

In the giraffe with a total height of 5 m., the heart is at a height of about 2.5 m., and it would be extremely interesting to know just how the giraffe avoids the development of filtration oedema in its long legs.
There can be little doubt that fishes swimming rapidly do not make respiratory movements at all, but obtain the necessary ventilation of the gills simply by opening the mouth.
Muscles do not use oxygen at a constant rate.
The affinity of blood or pure haemoglobins for oxygen is a complex phenomenon, depending upon a number of conditions, the most important of which are temperature and hydrogen ion concentration.
I found it possible to observe at least the superficial capillaries of muscles both in the frog and in mammals through a binocular microscope, using strong reflected light as a source of illumination. Resting muscles observed in this way are usually quite pale, and the microscope reveals only a few capillaries at fairly regular intervals.