108 * 
Wisconsin Academy of Sciences , Arts and Letters. 
appendages are always unsegmented.” For, in the above mentioned stage of 
development a distinct constriction of the ectoderm may be observed between 
the basal and distal portions; hence I believe that we are justified in regarding 
as segments the two parts of the appendage thus distinctly separated. On 
the twelfth day of development — sometimes even before — the plasma of 
the invaginated cells, whose roundish oval nuclei lie near the basal ends, 
acquire a very distinctly and finely fibrillar structure, resembling that of 
the epithelium of many excretory glands. In the above described cavity is 
collected a homogeneous, sticky secretion, which gradually swells out of 
the aperture in considerable quantity. It is easy to detect delicate threads 
of this secretion running from the large cells surrounding to the mass of 
the secretion filling the cavity. The structure of these glandular ap¬ 
pendages reminds me somewhat of the glandular temporary appendages 
[‘ dorsal organ ’] which I have described in My sis; I hasten, however, to 
state expressly that I do not wish to maintain any homology between these 
organs.” 
Interesting as is the account just quoted, Nusbaum goes on to describe a 
still more interesting condition. He says: “ I have further convinced 
myseif that the remaining stub-shaped abdominal appendages of Meloe are 
of a glandular nature. At the tip of each of these appendages there is also 
formed an invagination, which is. however, much shallower than in the 
appendages of the first abdominal segment, so that it does not form a 
cavity. The invaginated cells are closely juxtaposited, long and cylin¬ 
drical but not as large as those of the first abdominal appendages. They 
likewise secrete a sticky substance, though in less quantity than the afore 
mentioned organs of the first segment. Back of these invaginated cells 
lies a cavity communicating with the body cavity and filled with loose 
mesoderm cells.” The further fate of these organs was not traced by 
Nusbaum. “ The roundish terminal joint of the appendages of the first 
abdominal segment is very probably thrown off, while the basal portion 
together with the stub-shaped appendages of the other abdominal segments 
gradually grow shorter, flatten out and finally disapjiear entirely.” 
Before passing to a brief resume of the results recorded in the preceding 
portions of my paper, I insert a table of the insects, which have been studied 
with reference to abdominal appendages. In this list are included a few 
forms, in which no pleuropodia have been described. I am well aware that 
negative conclusions in regard to details merely read between the lines of 
works on the general ontogeny of a species are of very little value, but in the 
cases to which I allude, the probability of such prominent organs 
as the pleuropodia being overlooked by investigators who have care¬ 
fully studied insect embryos by means of sections is so small, that 
I do not hesitate to record their omissions as negative results. 
Most of the forms enumerated as having no pleuropodia were examined 
by Graber and myself with the express purpose of observing whether these 
organs were present. 
