lo Feb., 1910.] The Potato Eel-Worm. 89 



Worms. 



Xo living worms were seen in o\er 100 sections of mature potatoes ex- 

 amined, though in all there were female worms in the bladder- like or cystic 

 form containmg eggs in various stages of development, some containing 

 embryos fully formed and ready to escape. If the eggs are obtained by 

 scraping an infected potato, some acti\"e worms are sure to be found, the 

 scraping having ruptured the cyst and seme of the eggs and set the young 

 worms free. Drying for 24 hours kills the young worms; this, again, 

 differs from the onion worm which retains its vitality at all ages and begins 

 to move actively w'hen moisture is added after being kept in the dried 

 condition for over two vears. 



In the onion worm the cardiac bulb can be seen beating rhythmically ; 

 I have not been able to demonstrate' this in the potato w'orm. The onion 

 worm is viviparous and o\iparous, thus further differing from the potato 

 worm wdiich, as stated above, forms a cyst, the de\elopment of the eggs 

 going on after the parent worm has died. 



The whole life historv of the onion worm is (]uite simple, and can be 

 watched from the egg till the worms are full) grown and reproducing 

 their kind. If a fresh piece of onion be placed in a. dish containing onion 

 worms, in a few hours the worms are attacking it vigorously. No such 

 thing occurs on adding a piece of onion to a dish containing young potato 

 worms, nor do pieces of potato pulp or scrapings attract them ; in infested 

 soil the adult worms are feebly attracted if a piece of potato is attded 



So far as mv observations go, the potato eel-worm is low^er in the scale 

 of being and more passive than the onion worm. It resembles to a 

 certain extent Heterodera schachtii. which, according to Strubell, '' forms 

 the galls or swellings on the roots of manv plants especially tomatoes and 

 cucumbers. The free larvae of this form live in the earth and make their 

 wav into the smaller rootlets ; here the fem.ale larvae shed their skin, loose 

 their characteristic nematode form, and become citron shaped. The 

 embryos develop within the body of the mother, and, escaping through the 

 uterus, ultimatelv cause her death." 



Soil. 



In a specimen of soil brought by the Potato Expert, ^Ir. Seymour, 

 from Killarney, three distinct species of nematodes were found, one of the 

 species identical with the potato worm being found in 60 per cent, of the 

 slides examined. In soil obtained by Mr. Price from the onion district 

 of Portarlington, no worms were found ; though in a potato (Carmen, No. 

 T ) from the same land I found many worms in the rootlets, including a 

 female with an area of germinal cells similar to those found in the encysted 

 or bladder form. Many Avorms w^ere also found in the young shoots. This 

 potato was no doubt infected when planted. 



In a self-sown sample from the Agricultural High School. Warrnam- 

 bool, supplied by Mr. Seymour, emptv egg envelopes were seen ; a number 

 of worms w'ere found in the potato, many in the rootlets and a few in 

 the shoots. Manv worms w^ere also found in the sample of soil handed 

 to me at the same time. 



Specific Gravity. 



The worms float for a little while in a 5 per cent, solution of sodium 

 chloride, but very soon sink as the salt is taken up by osmosis. The eggs 

 have a slightlv higher specific gravity than the worms, probably because 

 there is more protoplasm in proportion to the superficies. 



