I 4 I 



iicvcr acquires. under the inrluence of the parasitic cysts. the hardness and con- 

 sistency of the normal secondary wood, as found in healthy roots, but remains 

 from the time of its birth by the division of the cambium cells until the moment 

 of its premature death, in a parenchymatous, soft and sap-filled condition. In 

 other cases of pathological alterations of plants similar observations may be made; 

 for example, in the reproduction of a morbid parenchyma, instead of hardwood, 

 in the case of the gum disease of certain trees, 1 ) and just in the same masses 

 as these may be found in the last case fully normal wood proceeding from thé 

 unafïected cambium; so we see by the transverse sections of the Gardenia roots 

 affected with Heterodera insular masses (fig. 94 x/>) of a woody structure identical 

 with the wood of the healthy root, tracing their origin from mother-cells lying far 

 distant from the parasitic cysts. 



V\K Q5. Disease of Gardenia roots. 



Fig 94. - Disease of (Jardenta roots. 



After this short description of the altered organ of the plant, let us now 

 return to the zoological side of the question. 



It is said above that the cysts are nothing else but the overgrown posterior 

 part of the body of the females, completely filled with eggs. These eggs hatch 

 in the mother-womb, and the young worms of the new generation find their way 

 to the outer world by boring a hole through their dead mother's body. The life- 

 history of these little animals is not fully cleared up ; it seems that they live in 

 the damp soil surrounding the roots, as dormant animals, till their reproductive 

 organs begin to develope, and that the moment of their invasion of the roots 

 coincides with their accelerated growth, which neccessitates a better supply of 

 food. From the observation of Carl Muller it appears that the process of copu- 

 lation and fertilisation. which have not vet been directly seen, must take place 



') I recently saw this fact with unrivalled clearness in a specimen of Theobroma 

 Cacoa of Surinam, for which I am indebted to Professor Suringar, of Leyden. Here, 

 as formerly described in these columns for the first time, a parasitic fungus was the 

 distinct cause of the gummosis. 



