Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1888. Excerpt: ... CHAPTER IV. THE EVOLUTION OF ANIMAL NEOPLASMS. "Our times may look with pride on the progress of modern morphology, whose importance is proved by the very fact that it is so destructive of previous views, and so fruitful in the most diverse directions." Billroth. In the preceding chapter I endeavoured to interpret the facts of pathological new formations in plants, in accordance with the doctrine of Evolution. I then claimed for the principles laid down, that they were equally applicable to Animal Neoplasms. It now remains for me to develop this part of the subject. Underlying all I shall have to say is the great principle, that the evolution of pathological new formations is but a modified repetition of the normal evolution. I propose then to treat of animal neoplasms in connection with kindred processes throughout the animal world. Hence, at the outset, the necessity of giving a brief sketch of animal organisation in general, as I believe it to be built up, both from the phylogenetical and ontogenetical standpoints. Animals, like plants, consist either of single cells, of groups of cells, or of aggregated cellular groups variously modified. Between the lowest forms of animal and vegetable life there is such close resemblance that no satisfactory line of demarcation can be drawn. This has led some naturalists to unite all such lowest forms, whether animal or vegetable, into a separate kingdom--the Protista, intermediate between the other two. I find it convenient to retain the name of Protozoa for the simplest forms of animal life, which consist of single isolated cells. These, like the Protophyta, have no sexual reproduction; new individuals arise by cell multiplication--by fission or gemmation, which is bud formation in its simplest form. Hence, we may...
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