Wolfes — Cytological Studies on Nemalion . 6 1 1 
of stains and other reagents were thoroughly tested, but in no instance was 
it found possible to demonstrate the presence of any organized material 
in this central region. Since this cavity is only about 3 in diameter 
its absolute section is secured only in the thinnest sections, and not in such 
as were chiefly used in this investigation. In these preparations the central 
body of the chromatophore is seen as a hollow ellipsoid, from the upper 
portion of which a slice has been removed in another section ; therefore, 
even at the median focus, the concave wall always appears, and being out 
of focus, presents a granular appearance as is shown in most of the figures. 
The fact, however, that such confusing appearances are not seen in the 
absolute median section, like that represented in Fig. 25 , which is drawn 
from a section 1 /jl in thickness, demonstrates, to the satisfaction of the 
writer at least, the absence of any body of such organization as is assumed 
to be characteristic of the pyrenoid by all recent investigators. It may be 
objected that the conditions just mentioned might be due to the fact that 
the contents had dropped out of such a thin section ; the essential agree- 
ment, however, seen in thicker sections and even in material which has not 
been sectioned, it would seem, make this supposition, to say the least, 
in the highest degree improbable. 
It should be mentioned in this connexion that Schmitz (’82) in 
speaking of the pyrenoid in the Bangiaceae and Nemaliae remarks (p. 52 , 
1. c.) : ‘ Bei diesen Algen namlich quellen die Pyrenoide bei Einwirkung von 
siissem Wasser, Spiritus, verdiinnter Essigsaure u. s. w. auf und vertheilen 
sich schliesslich vollstandig in dem umgebenden Losungsmittel.’ The 
possession of such remarkable powers of solubility by a distinct organ 
of the cell would certainly seem to be anomalous ; and, although in the 
somewhat extensive literature of the subject there is so little agreement as 
to the nature of the pyrenoid, it is perhaps fair to assume that we are here 
dealing with a wholly different structure. To indicate this diversity of 
opinion : Meyer (’83), for example, representing perhaps an extreme view, 
holds that the pyrenoid is of a crystalloidal nature and has no function 
other than that of serving as reserve material ; Boubier (’99), on the other 
hand, finds it to be a crystalloid, but with a characteristic reaction to stains 
and surrounded by a membrane of distinct and definite structure ; and 
further, Timberlake (’ 01 ) has given a most detailed and admirable descrip- 
tion of the structure and function of this body in Hydrodictyon> regarding it 
as proteid in nature and manifesting its activity by cutting off segments 
which are directly converted into starch. Whatever may be the true 
nature of the bodies investigated by these writers, it is very evident that in 
Nemalion there is no structure present which could be said even remotely 
to approach the conditions described. 
The chromatophore alone thus appears to be responsible for the 
constructive metabolism of the plant. No starch, however, could be 
