Author Description

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. 1905 Excerpt:... posterior piece cut at any level posterior to the cephalic ganglia is very slow and rarely if ever complete. Child 4 observed the same fact, and also in the case of lateral regeneration that " when they the cephalic ganglia are absent neither they nor the lateral part of the head removed are regenerated, though lateral regeneration of other parts may be more or less complete in the absence of the ganglia." In L. littoralis there is also a very marked difference in the rate and amount of regeneration of different kinds of pieces, and also in the behavior of the pieces. Pieces of any size and shape, in which the cephalic ganglia remained, responded quickly to stimuli that affect the normal worm, and in general behaved like normal animals; moreover those that lived regenerated rapidly. Even small pieces (cut out of the head with a straw), containing the eye-spots and cephalic ganglia and very little tissue besides, responded readily to light and touch, and crawled actively; in all cases in which such pieces survived, they quickly regenerated tissue in every direction, and in less than two weeks presented the appearance of small worms with heads very large in proportion to their tails (Fig. A, 7, 8). Pieces without the cephalic ganglia, on the other hand, behaved differently. They were sluggish in their movements, responded slowly and did not even stay under water, but were often found dried up on the sides of the dish. Also, as Child and Schultz found in the forms which they studied, anterior regeneration took place only to a very limited extent. Pieces cut at any level posterior to the ganglia often healed in such a way as to apparently prevent the growth of new tissue. After the worm was cut, the sides stretched very much and actually met in front...