40 
guished without any intervening substance between them. The same 
is the case in Fig. 5, taken from a longitudinal section of a Comandra 
haustorium on a Vaccinmm root. The location of this group of cells 
corresponds to the point jv in Fig. 3. Here one cell of the parasite, 
having struck a tracheid of the Vaccinium at right angles, has pene- 
trated it, and within its cavity has formed a peculiar, capitate expan- 
sion. The other Comandra cells are about to break throngh the wall, 
while the adjoining cells of the foster-plant have already been partly 
disintegrated.* 
Fig. 7 represents a cross-section of some vessels that have been 
entirely separated from the plerome of the Aster root by the rapidly 
growing apex of the haustorium, which, like a wedge, exerts a down- 
ward and sidewise pressure. Some of the cells (pitted vessels) are 
very much indented or compressed laterally. The same group, less 
magnified, will be found in Fig. 6, and another similar one, on the 
other side of the same haustorium. In this case, too, the cells of the 
parasite are seen In close contiguity with those of the foster-root. 
Fig. ID, from a point z in the tangential section, Fig, 8, shows 
some cells of the parasite, that have descended vertically, and then 
have curved outward, to the right (compare Fig. 3), as they meet a 
large pitted vessel of the Aster and crowd into it, their walls closely 
pressing against those of the vessel. Some other descending cells 
are breaking the connection between this cell and the neighboring one. 
A similar vascular cell of the Aster root, from a place corres- 
ponding to the point w in Fig. 8, but somewhat nearer to the apex 
of the haustorium, is shown in Fig. 9. It has been detached from 
the other vessels and is now wedged in between the actively growing 
peripheral and central cells of the interior haustorium. This figure, 
at the same time, explains the structure of the '' stripe of separation," 
ss. We see the cells on both sides of it, but especially toward the 
circumference, yielding to the expansive force of the haustorium, and 
we can easily imagine that some of them will soon be totally crushed, 
and that their membranes will help to increase the mass of the *' sep- 
aration stripe/' We ' 
Ihey appear very much reduced in width, the innermost exceedingly 
so. Using a lens of lower power we might easily take this layer of 
partly and totally collapsed cells for the *' homogeneous, yellow 
mass" spoken of above, especially after treating the section with 
alkalies for the purpose of making it transparent. 
I think what I have said in explaining the five last figures will "be 
sufficient to show that, in Comandra, there exists a direct and unob- 
structed communication between the cells of the haustorium and 
those of its foster-root. 
Hoboken, March, 1883, 
Aspidium Lonchitis, Swz.—The range for this fine fern is now 
extended to California, it having been collected by Mr. Pringle at 
Castle Lake, Siskiyou Co., September 5, 1882. 
Geo. E. Davenport. 
* By the shading it is simply intended to show the wall of the tracheid per- 
specltvely. '^ 
