Oct. i, 1917 
New Parasitic Nema 
33 
(3) The geographical distribution of the pest is suggested by its 
presence in Florida, Georgia, North Carolina, New York, and Michigan. 
(4) The occurrence of this disease under such different climatic con¬ 
ditions and in such a diversity of hosts makes it certain that the nema 
# 
causing it is another species which, like some other destructive members 
of its genus, can adapt itself to widely varying conditions. 
(5) As yet too little is known about this parasite to accurately estimate 
the damage done by it. 
(6) The occurrence of the parasite in the tubers of the potato is a 
peculiarly significant fact and again points to the necessity of being 
particularly careful to plant only perfectly healthy potatoes. The 
mercuric-chlorid treatment of potatoes, as for scab, decreases the 
vitality of the nemas. 
APPENDIX 
Figure 5 is a diagram illustrating the decimal formula used for nematodes; 6, 7, 8, 
10, 6 are the transverse measurements, while 7, 14, 28, 50, 88 are the corresponding 
longitudinal measurements. A formula assembling these measurements appears 
just below the diagram. The unit of measurement is the hundredth part of the length 
of the body, whatever that may be. The measurements become, therefore, per¬ 
centages of the length. The absolute length of the nema is given in millimeters as a 
final term, in this case 1 mm. 
14 * 
28 * 
io> 88> 
Magnified one hundred diameters. 
Fig. 5. —Diagram showing measurements of a nema and the corresponding formula. 
The measurements are taken with the animal viewed in profile; the first are taken 
at the base of the pharynx, the second at the nerve ring, the third at the cardiac 
constriction or end of the neck, the fourth at the vulva in females and at the middle 
(M) in males, the fifth at the anus. The presence, situation, form, and extent of 
various organs is indicated in the formula by self-explanatory marks; in this case, 
the excretory pore, wings, spinneret, and sexual organs are so indicated. The formula 
thus becomes a sort of conventionalized sketch of the organism. 
In this article the writer has adopted the improvement suggested by Micoletsky, 
and have split the measurement indicating the extent of the female sexual organs so as 
to show the relative proportions of the anterior and posterior branches. Thus, 5o-f-5 
indicates that the entire apparatus, consisting of two outstretched parts, occupies 55 
per cent of the length of the nema, but that the posterior branch is a mere rudiment 
only five one-hundredths as long as the body. 
