Transactions of the Royal Society of New Zealand Volume 18 - Brossura

Zealand, Royal Society Of New

Brossura

ISBN 10: 1130708233 ISBN 13: 9781130708233

Casa editrice: RareBooksClub.com, 2012

Riassunto

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. 1886 Excerpt: ...into their cases with lightning rapidity, remaining concealed until the danger is passed. Their food probably consists of the green weed, although they are perhaps carnivorous, feeding on the rotifers and other animalculas, which swarm in the water where they are found. With regard to the method employed by the young larva in constructing, and subsequently enlarging, his case, I can give no positive information, although it is undoubtedly made of a viscous fluid secreted by the insect, which hardens when exposed to the water; this secretion is no doubt analogous to the silk of caterpillars, which always exists in the form of a gummy fluid before being spun. In a few Lepidopterous larvae (Centra, etc.) it is employed as such to construct the cocoon, which is consequently of a much stronger consistence than where the ordinary silk is used. When about to change, the insect fixes his case down by four ligaments, two at each end, the extremities of these being firmly fastened on to a stone; he then closes the small aperture, and constructs a curious arch-shaped partition of dense material inside, a short distance from the broad end (fig. 2). In about a week's time he is transformed into a pupa, having the limbs, etc., free from tht body, but incapable of motion. The fixing down of the case prior to the change may be easily performed by the larva from each of the apertures, which are no doubt left open till the last for this purpose. Before the final transformation the pupa breaks through the partition at the broad end of the case, and wriggles to the surface, the imago ascending a blade of grass to dry and expand its wings. The little exuvia of the pupa may be often noticed floating on the water, and the empty cases are very conspicuous on the sides of a glass a...

Su questa edizione

• Editore: RareBooksClub.com
• Data di pubblicazione: 2012
• ISBN 10: 1130708233
• ISBN 13: 9781130708233
• Rilegatura: Copertina flessibile
• Numero di pagine: 186