60 
Annals of the Tkansvaal Museum. 
persist, the branching of the tracheae is seen, and the origin and 
course of the tracheoles. In all such preparations studied the 
tracheoles from different cylinders anastomosed, forming a close 
tracheolar network throughout the area of parenchyma. Although 
the tracheoles are generally cut in sections parallel to the axis of 
the cylinder, yet even here occasional demonstrations of anastomosing 
are to be found. I have found no indication of the penetration of 
the parenchyma cells by the tracheoles ; thev appear always to be 
intercellular in their course. 
Wielowiejski found anastomosing of the tracheoles to be the rule 
in Lampyris splendidula, although he admits of some exceptions. 
Wistinghausen and Holmgren, in their studies of tracheal-ending 
in the silk glands of caterpillars, found the same anastomosing of 
the tracheal capillaries. Emery, however, states that in Luciola the 
tracheoles always end free. 
Max Schultze, in 1864, in studying osmic acid preparations of 
Lampyris splendidula , found at the periphery of the cylinder certain 
darkened cell-like bodies into which the smaller tracheal twigs 
entered. Failing to find any continuation of the tracheae beyond these 
bodies, he called them the “tracheal end-cells”. 
In osmic acid preparations of Photinus there is always a blacken- 
ing of the smaller tracheae at the point of division to form the 
tracheoles ; the tracheoles themselves are blackened throughout their 
extent. Surrounding the point of origin of the tracheoles the tissue 
is also more or less blackened. In the typical preparations with this 
fixation there are darkened rounded bodies which might seem at first 
to be cells. In other preparations there are irregular masses instead 
of cell-like bodies. The dark cell-like bodies are found in Luciola , 
where the structure closely resembles that of Photinus. As these 
bodies are only found in osmic acid preparations, Emery regarded 
them as an artifact and not as true cells. In Photinus they occur 
only in osmic acid material, vary considerably in different material, 
and are always accompanied by an apparent shrinking and distortion 
of the tissue of the entire cylinder. It would seem probable, there- 
fore, that they are an artifact. In any case they are incorrectly 
termed “ end-cells ”, as the tracheoles extend to a considerable length 
beyond them. 
Wielowiejski and Bongardt have found the “ end-cells ” described 
by Max Schultze in Lampyris splendidula, but have also found that 
they do not contain the ultimate tracheal endings, the tracheoles 
passing out of them. In Lampyris , it is asserted, the “ end-cells ” 
are formed by the epithelium of the tracheoles. In the “ tracheal 
capillary end network ” found by Wistinghausen and Holmgren in 
Lepidopterous larvae, it is stated that the epithelium is spread out 
in a web-like manner to form the “end-cells”. Wielowiejski, 
Bongardt, Holmgren, and Wistinghausen thus all agree that the 
tracheal epithelium is abnormally developed and spread out to form 
the “end-cells”, or “transition cells” as Holmgren more correctly 
terms them. Emery considers the cylinders of Luciola as homologous 
to the “ end-cells ” of Lampyris , and as modified tracheal epithelium. 
The cylinders in Photinus are clearly shown to be of cellular 
structure. They contain numerous small nuclei near the tracheal 
axis, but clearly separate from the tracheal epithelium, which may 
be traced even to the smaller branches. Throughout the photogenic 
