(>88 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



with a central nucleolus ; the latter are the persistent vegetative nuclei, 

 the former presumably the reproductive and descended from the zygote 

 nucleus. The latter are indeed something more, for they appear to be 

 directly transformed into the spores, which are thus imbedded in a 

 nucleated epi plasm. 



As the spores mature a minute central nucleus again becomes evident 

 in each. Juel places the genus among Hemiascece, but notes its relation 

 to Pcronosporece and to Eremascus among the true Ascomycctes. It 

 will be seen that there are still gaps in our knowledge of the cytological 

 processes of this most interesting form. — M. H. 



Heredity. 



Diseases, Plant, are they Hereditary ? By Alfred R. Wallace 

 {Garden, No. 1,591, p. 317 ; 17/5/190). — A carefully thought-out article in 

 which Dr. Wallace says : "In a very interesting and original work, ' The 

 Present Evolution of Man,' by Dr. G. Archdall Reid, this subject is very 

 fully discussed, and it is shown that, with very few exceptions, there is 

 no proof whatever of the inheritance of disease in man, but only of the 

 inheritance of a tendency to the special disease of the parent, so that, 

 under similar unhealthy conditions of life or of exposure to infection, 

 the child is likely to contract the same disease, which will thus appear to 

 be hereditary without being really so. This is clearly the case with gout 

 and consumption, which have both been held to be hereditary, but in no 

 case has an infant been born suffering from these diseases." — E. T. C. 



Doubling caused by Parasites. 



Double Flowers and Parasitism. By M. Molliard (Comp, Bend, ; 

 October 7, 1901). — Certain parasites determine the formation of double 

 flowers in the plants in which they live ; as examples the flowers of 

 Knautia arvensis attacked by Peronospora violacea ; those of Matricaria 

 inodora infested with Peronospora radii ; Viola sylvestris shows petalody 

 of the stamens when Puccinia violce is present as a parasite. 



The author suspects that the double flowers of our gardens originated 

 owing to the presence of a parasite in their roots. In support of this 

 view the case of Saponaria officinalis is cited. 



The size of the Saponaria with double flowers is obviously different 

 to that of those producing normal single flowers. The internodes are 

 shorter, the nodes more swollen, and the rhizome thicker and its structure 

 less differentiated, the lignification in particular being less pronounced in 

 individuals attacked by Sorosporium saponaria. In such infested 

 individuals the root also shows the presence of tubercles, from which 

 under proper treatment a copious mycelium belonging to a Fusarium is 

 developed. 



In Primula officinalis again the rootlets of plants bearing double 

 flowers are infested with a fungus called Dcmatium. According to 

 Molliard the dioecious forms of Pulicaria officinalis are infested in the 

 root by a parasite. 



The author produced by experiment petalody of the stamens of 

 Scubiosa Columbaria, through the influence of an eelworm called 



