Journal of Proceedings. Ixxi 



our own specific diseases. We must remember that the sap-flow in 

 plants is by no means analogous to the circulation of the blood in animals, 

 and there is an absence of the complex nervous system. A nearer analogy 

 might be traced in the known specific action of various blisters and 

 irritants, or in the production of local abscesses, festers, or like simple 

 humours, from the inflammation set up by the irritating presence of 

 some foreign substance. Mr. Fitch said that although a firm believer 

 in the mechanical oval and larval irritation theory, he thought it pro- 

 bable that the application or removal of pressure, the stimulated growth 

 to throw off the foreign substance introduced, and other secondary 

 causes, also came into play. He had referred to the production of 

 warts, and to make a rough comparison he would instance a hairy 

 wart in which we found an excessive development of cuticle and an 

 increased development of the vascular secretory structure, with the 

 exudation of an abundant quantity of fluid, causing the extra growth 

 of hairs ; compare this with the familiar " Kobin's pin-cushion," or 

 Bedeguar gall of the rose, where we had excessive development and 

 thickening of cambium tissue and bark with an increased afflux of 

 nutritive matter, resulting in the enormously developed growth of 

 leaves, remembering that the so-called " hairs " with which the gall 

 is covered are really leaves abnormally developed, with scarcely any 

 parenchyma between their fibro-vascular bundles. Dr. Pearce must 

 also remember that we are not yet by any means fully acquainted 

 with the relationship between the formative stimulus (mechanical or 

 otherwise) and the supporter of the stimulus ; this also answered, or 

 rather failed to answer, our President's question as to why the galls, 

 quite constant in themselves, which occur in exactly similar situations 

 should exhibit such varied forms. Our present knowledge was not able 

 to give a ready solution to this involved problem, but we know that 

 there are still many well-known but ill-explained facts in both animal 

 and vegetable pathology. Mr. Fitch expressed a hope that some of the 

 structural botanists in the Club would turn their attention to these 

 important and interesting points. 



The analogy between the various skin diseases in the human subject 

 attributable to fungoid presence, and the numerous varied and well- 

 marked fungoid vegetable galls, alluded to by Dr. Pearce, stood on a 

 similar footing, but with a more perfect concatenation. The subject of 

 the useful chemical properties, remarked upon by Mr. Letchford, was of 

 true commercial importance, and deserved more attention in this country 

 than it at present received. The tannic and gallic acids were undoubtedly 

 more concentrated in the substance of certain oak-galls than in the oak 

 bark itself ; but why we should annually import from £70,000 to £80,000 

 worth of galls for tanning purposes, while our own large crop of oak 

 marble-galls is unmarketable except for the manufacture of rustic 

 baskets and similar trinkets, requires further explanation. Chemical 

 analysis hardly warrants this neglect of our native galls. Mr. Fitch 



