198 



T.Vnfl,,!«! !5v*^^*'*^J statement that Rhlno oola sp eolosa 

 pi'oduces other galla on the leaves oTa- speGles S S^r ^ia ^ 



BesflerL't^ '\?°"^ ir Aragon^.neeL'Se'lxfct^??Jl?. 

 ^J«^! ' ^\*v.® ^^i^ productions of Rhinocola. kataplas- 

 mas are probably the ones concerned. r^^^^pxat. 



tfirr,-,!^ ^^/i^®^^^ ^^^^,®^ attention to the fact that the ex- 

 h! ?^J and internal peculiarities of pro so plasmatic galls may 



iv^i? JS ^*^°!^ '^^ **^® ^^^^ P^-^°" gi^^^n o«t ^y *he parasite, 

 h« ™i??v''S"^*^*^°,^,®£ *?® proportions of size and form cannot 

 be explained so well by the quality of the infection as bv the 

 extent of Its action and Its type. In prosoplasmas, gall" ani- 

 mals axe involved, which cannot at will leave or change the 

 place Unfeoted as can possibly be done by wandering leaf-lice 

 etc, nor can they extend it irregularly, or indefinitely, as do 

 outgrowing fungi, only a narrowly limited field of infection 

 is produced, Further, the poison causing a production of the 

 gall is introduced Into the plant only once with the deposition 

 Si f,.*'^^ • ®^ ^* ^® effective for a comparatively short time - 

 Tnus the period of stimulation is evidently very limited. Like 

 this, the development of the gall soon ends. Although the galls 

 of the Gymnoeporangia eto. continue growth for years, never r 

 t^0A\ IZ^^^^^S f^ny real final T^ mature^'sta^e . prosoplasmas reach 

 \^(ii} their last phase of development a few days or weeks after the 

 deposition of the eggs, corresponding to the rapid developmen- 

 tal progress of the parasites. 



In speaking of a limited period of stimulation, we think 

 Indeed •nlyof the moat important of the stimuli, tib whose 

 aotlon the tissues which produce the gall and the gall itself 

 are exposed; i, e, of the chemical stimuli arising from the 

 gall poison. However, for at least some prosoplasmas, it has 

 become evident that another kind of stimuli co-operates in 

 their production and formation - wound -stimuli. Either the 

 gall mother injures the plant organ, before she deposits her 

 ^SBt thereby causing the production of callus tissue, or the 

 growing occupants of the gall gnaw its tissue. In the present 

 consideration;,, the second is the mere Important case, because 

 there exist in it stimuli of long continued, ever repeated ac- 

 tion. We find that the tissue of the galls responds to the 

 Stimulus of injury with the same reaction as wound normal tis- 

 sue. Callus hypertrophies are produced fin the elliptical 

 galls of the Cjmipides infecting oaks; see below p, 264), or 

 callus hyperplasias (as In the galls of Mema tus vftll laner 11 ) 

 the formation of which can be continued iJUJng efler the form 

 and size of the gall have reached their JUiat stage; the impor- 

 tant external characteristics of the gall are not Influenced 

 by these supplementary, long continued phenomena of growth. 

 In katsplasmas, on the contrary, the chief role is played by 

 w»und stimuli and by those of gnawing which proceed uninter- 

 ruptedly from the producers of the gall. Their effect -Is de-. 

 terminative for all the qualities of the gall and the assump- 

 tion is a propos, that possibly in many cases, rio other stimuli 

 are effective. 



According to Eckstein, Pflanzengallen u. Gallentiere. 

 Leipzig, 1891. 



