982 Carter .■— Reconsideratio 7 i of Origin of ‘ Iransfusion Tissue \ 
transfusion tissue, that of its function is one as to which curiosity would 
naturally be felt during the course of an examination of it. An attempt to 
throw some light on this was made by placing living seedlings of various 
species with their roots in a watery solution of eosin. After standing there 
one to three days sections of the cotyledons were cut and placed in a mixture 
of acetic alcohol and glycerine on a slide, and examined at once. The seed¬ 
lings usually withered badly under this treatment, and when the eosin was 
replaced by aniline blue the internal tissues were not coloured at all. 
With those in eosin it was sometimes possible to see, in spite of the rapidity 
with which they were decolorized, that the transfusion tracheides contained 
the eosin solution, but this unfortunately was indecisive with regard to the 
question whether their function is that of conduction or storage, so that 
the point remained open. The mesophyll was’ also coloured by the eosin 
in most cases. Scheit 1 has pointed out that transfusion tissue is much 
less abundant in the leaves of those species which grow in dry places 
than of those which have a damper habitat. The short and stumpy form 
of the tracheides which has been pointed out by all who have described 
them in leaves, and which is equally noticeable in the cotyledons, seems to 
suggest storage tissue rather than conducting elements. It is also interest¬ 
ing to note that when transfusion tissue is found in Gymnosperms or else¬ 
where, it is always in structures exposed to xerophytic conditions. 
Summary and Conclusions. 
1. Since the distribution and nature of transfusion tissue in the leaves 
of Conifers make the hypothesis that it owes its origin to a modification of 
centripetal xylem a tenable one, investigation was made to see whether its 
point of origin in the cotyledons could throw any light on the matter. 
2. It was found that the first-formed transfusion tracheides in the 
cotyledons examined appeared in such positions and were of such a size as 
to make it appear improbable that they arose, in these organs at any rate, as 
an extension of the development of the centripetal wood. A comparison 
of these tracheides with the other tissues of the vascular strand suggests 
rather that they develop from the parenchyma. 
3. No direct light is thrown by the examination upon the question 
whether the transfusion tissue serves for conduction or storage, but there is 
a slight bias in favour of the latter view. 
1 Die Tracheidensaume der Blattbiindel der Coniferen. Jenaer Zeitschrift fur Naturwissen- 
schaft, 1883. 
