270 MINNESOTA STATE HORTICULTURAL SOCIETY. 



mouth can be seen as a slender cylindrical spear broadened at the base, 

 which ends in three short lobes. This hollow spear can be extended at 

 the will of the animal, and is moved by a pair of muscles. The spear of 

 a male is very similar, and is shown in Fig. 5. If this spear-like organ 

 did not perform slight movements, the head, nor the whole animal, would 

 even suggest the fact that a living animal was before us. 



At this stage of existence the cyst contains numerous fat-globules, and 

 consequently the body is too opaque to show clearly the determinations of 

 the internal tubes or their connections with the the body wall. At 

 the posterior end of the cyst may be seen oblong bodies within the tubes, 

 or free in the body cavity ; these bodies are the eggs, and the coiled tubes 

 are the genital tubes. As it would take too much of your time, the 

 minute details of the animal's structure will not be discussed, and only 

 the essential parts will be mentioned. 



Eggs— Immense numbers of eggs are found in the ovaries. Packed 

 closely together they possess a compressed form; free they assume the 

 usual oval form. Each egg contains a large nucleus and a distinct nucle- 

 olus. The mature egg is from three to four thousandths of an inch in 

 length. If ready to hatch it contains a worm-like object, coiled up three 

 to four times within the egg membrane. When the worm leaves the egg 

 it throws off its skin for the first time, and is now ready to enter the bat- 

 tle of life. As the female remains in the cystic state and is surrounded 

 by the tissues of the plants the young worms soon completely fill the cav- 

 ity of the cyst. These young worms just born are from twelve to sixteen 

 thousandths of an inch long and look exactly like vinegar eels. But the 

 poor things, although so very active, are prisoners, being enclosed by 

 prison walls composed of more or less hard plant tissues. If fortunate 

 they are favored by cracks in these walls caused by the decay of the 

 tissues, and they soon find means to escape; but otherwise, and not to 

 starve, they have to actually batter a hole in the prison wall through 

 which they can escape. Taking position with the head end against a 

 cell-wall, the worm thrusts forward the exsertile spear, which strikes the 

 cellulose wall forcibly, when it is drawn back and thrust out again. This 

 process is repeated until a hole is made through the wall large enough to 

 admit the body of the worm, through which it passes, and by successively 

 battering down the cell-walls of the surrounding tissues it makes its way 

 to freedom outside of the gall, or to a fresh portion of the same root. 

 Having escaped from its coniinement by one of these three courses, it im- 

 mediately selects another part of the root, or a fresh young rootlet. 

 Bringing into play its exsertile ram it forcibly gains entrance to the 

 healthy tissues of the root. The attacked plant, not able to expel the in- 

 vader, bends its energies in a vain endeavor to repair the injury to the 

 roots. Increased development of cells takes place, and normal ones are 

 turned from their proper position and function and become also very 

 much enlarged. The result is the formation of a gall, an increase of 

 tissues in the root, which supplies food and protection for hundreds of 

 the worms, all which lessens the energies of the plant normally directed 

 to the production of leaf and fruit. 



The larva wanders for a time through the tissues of the plant and An- 

 ally comes to rest. After moulting a second time it passes into a truly 

 parasitic condition. 



