Zoocecidia

Abstract

Zoocecidia or the galls caused by animals are, as mentioned in the beginning, limited neoplasia, the development and growth of which are strictly dependent upon the continued stimulation of the plant cells by the cecidozoa, so that the gall tissue is not autonomous, like, for example, the crown-gall tissue (vide Chapter XV). This limited character of zoocecidia may perhaps be the result of nutritional or structural barriers, rather than an intracellular physiological barrier. Though no genetic changes, in the strict sense of the term, have so far been observed to arise, polarity changes, hypertrophy, hyperplasia, abnormal metamorphoses, etc. in certain zoocecidia, especially the galls caused by Cynipidae, may be caused by an alteration in the genetic products of the plant cells, such as are often induced by viruses or certain nucleoproteins. It has not been possible, at least up to the present time, to raise successfully in vitro tissue cultures of fragments of even the most promising zoocecidia. When this can be accomplished, the way will perhaps be opened up for investigations, leading to the solution of some of the obscure problems in cecidology.