REPOKT OX BANANA DISEASE PREVALENT AT ALEXANDRIA. 845 



the cause of the disease, their presence being exclusively a resulting 

 consequence. 



Microscopic examinations of the roots with the knobbed appearance 

 showed the presence of so-called egg-sacs. To one acquainted with the 

 history of parasitic worms, this fact in itself is sufficient evidence that a 

 species of nematode was present. The so-called egg-sacs are full-grown 

 females, whose bodies are so strangely swollen as to attain a sac or pear 

 shape and are thus quite incapable of locomotion. Inside the motionless 

 sac the ova of the worm are found in different stages of development. 

 Of this genus (Heterodera) three species have hitherto been known. One 

 of them, H. Schachti (Schmidt), lives on sugar-beet, having some twenty 

 years ago caused great damage to the beet crop of Germany ; a second, 

 H. exicjua {Meloidogyne exigua Goldi), infests the roots of the Coffee 

 plant, having caused great havoc during the years 1885-1888, completely 

 destroying plantations in large districts in Brazil. The history of the 

 latter is very interesting and instructive, inasmuch as the disease could 

 be traced back to 1869 : that is to say, sixteen years before the outbreak 

 became really serious. Nothing was known of the pest, nor were any 

 attempts made to cope with it, until the year 1887, w^hen an area of 

 about 715,000 feddans was infected and the cultivation of Coffee rendered 

 impossible. The similarity to the present case is striking. It has been 

 known for some three or four years that a Banana disease existed in the 

 district around Alexandria. The disease was first located in a small 

 area, then at some little distance from the first observed area, and finally 

 has now spread in the whole neighbourhood, not only infecting planta- 

 tions, but having found its way into private gardens. 



The third species known, H. radicicola (Miiller), is the most interest- 

 ing because it is known to attack the roots of Bananas. About 1880 

 some specimens of Musa Lacca and Micsa rosacea, cultivated in the 

 botanic gardens of the University of Berlin, showed signs of disease and 

 it was decided to transplant them. During this process, the strange 

 knobbed appearance of the finer roots was noticed, and microscopic 

 examinations showed the worms to be present, and their evolutions were 

 studied. It appeared that the ova contained in the egg-sacs or cysts in 

 the adult and immobile females, after having developed and left their egg- 

 shells, escape from their parent. The latter then gradually dies. The 

 worms then make their way through the tissues of the root and enter the 

 soil. They wander about here for some time, growing slowly until they 

 find another root into which they enter, thus transferring the disease 

 from one root to another. Once within a new root they grow rapidly 

 to sexual maturity, and after impregnation the female develops into the 

 original egg-sac or cyst. Such is the life-history of H. radicicola, and 

 by analogy it is extremely probable that the species of Hcterodera infect- 

 ing Egyptian Bananas is very similar, although the species itself is not 

 H. radicicola. This latter possesses within its mouth-cavity a very fine, 

 sharp protrusive boring dart, which apparently serves to pierce the walls 

 of the tissue of the root and thus facilitate the entrance of the worms. 

 In the species found in Egyptian plants this is wanting, thus indicating 

 that the species is not identical. 



In the case of the disease found in Alexandria matters are complicated 



