Arthropods [noun]

Audouin gave the detailed demonstration of this by his accurate and minute determination of the pieces of the arthropod skeleton.

Turn the Arthropod on its back and the relative positions of the systems of organs are the same as in the Vertebrate.

Instances are seen in the Tunicata, and in various parasitic arthropod forms, such as Lerna, etc.

Such an arrangement suggests that in the ancient arthropod type a double segmentation existed, viz.

These cavities both in the vertebrate and in the arthropod disappear before the adult condition is reached.

The highest type among Annelida is found in the Chtopoda; from them, therefore, the original arthropod type must have sprung.

Thus the nervous system is dorsal in the Vertebrate, ventral in the Arthropod.

In other words, without the arthropod host the disease-producing organism cannot complete its development.

We now have to consider the cases in which the arthropod acts as the essential host of a pathogenic organism.

In other cases, it is the asexual stage of the parasite which is undergone, and the arthropod then acts as the intermediate host.