290 ^HE Microscope. 



As a pioneer in this vexatious business, I venture to describe 

 some of my mistakes and successes, hoping others will avoid the 

 first and surpass the last, aided by my brief sketch. 



These nematodes are easily found in the " knots," or better 

 called " galls," upon the roots of the bean, pea, tomato, celery, 

 parsnip, beet, turnip, okra, egg-plant, radish, cucumber, melon, 

 squash, peanut, cotton, Irish potato, clematis, colias, dahlia, 

 amaranth, weeping-willow, English walnut, fig, plum, peach, &c., 

 as well as upon the roots of weeds, like Pursley, Jerusalem oak, 

 tea-weed (Sida)^ careless weed (Amarantus spinosa and retro- 

 Jiexus)^ poke weed, coffee weed, &c. I give this partial list for 

 the benefit of our Southern microscopists, that I especially hope 

 will give it their attention. 



Let the experimenter visit a truck-patch or field of Pindars 

 (A7'achis), and if he can find plants of the tomato that look as 

 if withered by sudden heat, or Pindar stalks with stunted 

 growth, pull them up, and see if the roots are not knotty, 

 abnormally enlarged, with softening spots, or with the bark of 

 the root decayed so as to slip easily. The appearance of the 

 nodulated roots is characteristic, often like strings of beads in 

 the smaller roots of celery, okra and cotton, or like rapidly- 

 decaying fungoid growths on the willow and cow pea {Dolichos 

 catiana). Figure 6 shows a cow pea root, from nature. 



Breaking open one of the larger galls of the cow pea or to- 

 mato, the gravid worms are easily visible — especially if the gall 

 be discolored by decay — as minute, pearly white, flask-shaped 

 bodies, occasionally attaining the diameter of five millimetres. 

 Carefully picking them out with a fine needle (one with a flat- 

 tened and blunt point is best) and transferring them to a slide 

 with a drop of water, a low power easily shows the mature female, 

 the snaky head and enormous body, as shown in figure 1. 



Scraping the diseased tissues with a blunt-edged knife, add- 

 ing a few drops of water and filtering through coarse flannel* 

 into a deep watch-glass, will get rid of most of the vegetable 

 tissues, and in a few moments the eggs, immature and male 

 worms will settle at the bottom, and a drop of this sediment, 

 obtained with a pipette, will show on a slide most or all of the 

 forms given in figures 2, 3, 4, 5. 



By boiling the galls found on Irish potato, dahlia, coleus, 

 willow and radish, and making sections, fine specimens for 



