There are a number of veins and arteries attaching to the heart. The superior and inferior vena connect to the right atrium, while the pulmonary veins connect to the left atrium. The pulmonary artery connects the right ventricle to the lungs, while the aorta connects the left ventricle to the body.
Darwin was a revolutionary scientist in the field of biology and evolution. He managed to notice that the animals are changing over time, and that one species can become much different over time because of the changes in its environment. The theory of Darwin was that the species change in accordance to their environment, thus they develop advantageous traits so that they can be more competitive. As there were lot of fossils found in this period of time, so there was a lot to compare with, great deal of scientists accepted Darwin's theory, though they had lot of criticism for some other theories of his.