Mar. 17, 19*3 
Agamermis decaudata, a Nema Parasite 
925 
the driving mechanism is left outside the host, but young larvae in which 
the node is unripe may take the driving mechanism inside, where, in 
the course of a few days, it is shed. The nema requires from two to 
five minutes to enter the host. This period is often preceded by a few 
minutes of waiting—perhaps devoted to some internal preparation 
for the onslaught. Entrance is bored at any thin part of the cuticle 
of the very young larva of the host—namely, on the head, thorax, 
abdomen, or legs. 
The cephalic end of the free-living larva is highly specialized. No 
particular reference is made here to its acute, hollow, protrusile spear, 
or its six inconspicuous cephalic papillae, amphids, nerve-ring, oeso¬ 
phageal lumen, and longitudinal chords, 3 most of which closely resemble 
those of the “Mermis albicans” of Hagmeier. The bifurcated, sym¬ 
metrical, two-celled renette lies in the neck behind the nerve-ring. 
The oesophagus ends posteriorly in a short, small, cylindroid swelling, 
which at intervals of about a second may exhibit the sudden peristaltic 
motions characteristic of the swallowing act of nemas. 
The intestine comprises two sections, of which the posterior is about 
two bodywidths long. The four times longer anterior section, com¬ 
prising sixteen cells, has a distinct, narrow, refractive, tubular lumen, 
and is flanked by three unequal glandular structures having their free 
ends caudad, the largest of which, the right, extends throughout the 
length of this section of the intestine, while the two others—equal, 
narrower, and on the left—have only half that length. These organs 
are packed with minute dodecahedral, colorless, in the main nonstaining 
(carmine, osmic), refractive granules, of which those in the largest organ 
are very much the largest; beside this, there are physiological differ¬ 
ences, in that the two smaller organs stain differently intra vitam from 
the large one and behave differently after the larva enters its host. 
During the early days of parasitism these three organs disappear, so 
they evidently have to do with the physiological changes connected with 
the inception of taking in food from the host. The intestinal lumen in 
the 20-30-celled posterior section is of a different, nonrefractive character 
(wider and surrounded by a very thin nonrefractive wall), and this section 
presents the elements commonly seen in the intestinal cells of free-living 
nemas. 
The sexual blastomeres nearly always lie in the axil between the two 
portions of the intestine. 
After entering the host the posterior portion of the intestine changes 
and gives rise to a syncytiumlike (?) structure of relatively enormous size. 
As the three glandular organs disappear, the anterior 16-celled section of 
the intestine also begins a relatively huge growth, at first (20 days) 
forming a somewhat moniliform series of 16 organs (urocytes?) with large 
nuclei very like the four organs of Tetradonema (1). The early growth of 
the two portions of the intestine is not so very unequal, so that the sexual 
anlage comes to lie nearer the middle of the body. Along with this enor¬ 
mous growth of the intestinal elements the longitudinal chords, 3 especially 
the lateral, increase greatly in volume from back to front. 
In spite of the fact that the free-living decaudata larvae will live for 
hours or even days on thawing ice, when placed in water or moist earth 
at 32 0 F. they are much injured by the congealment. Two or three 
such experiences kill them. One exposure to zero Fahrenheit kills them. 
It seems probable that they can not survive even light frosts in nature. 
* Hitherto usually referred to in the literature as the “longitudinal fields.” 
