ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



causing the disease is Septoria PetroseMni var. Apii. It has spread very 

 widely in recent years, and caused great loss. It had been already 

 established that the fungus could be carried by the seed, the spores 

 being partially embedded in the pericarp, but Pethybridge considers that 

 it may also be further disseminated by passing on to wild plants. 1 1 e 

 himself found it on plants of wild celery in W. Gal way. Inoculation 

 experiments proved the fungus to be the same as the one on cultivated 

 celery. 



J. K. Ramsbottom * has worked out the disease of Iris, known as 

 leaf-blotch, which generally appears in August and September, though 

 often present in spring as well. The rhizomes are not directly affected 

 by the disease, but the plants as a whole are seriously weakened, and 

 eventually become exhausted and die. 



The fungus causing the disease is a Hyphomycete, Heterosporium 

 gracile, which invades the plant tissues ; the conidiophores rise in tufts 

 through the stomata of the leaves and bear single conidia at their 

 apices. The conidia, at first colourless, become brownish -olive and 

 septate ; they germinate in a few hours, and plants infected produced 

 the diseased spots, and finally conidia, in about six weeks. 



C. J. E. Dalmeda f comments on the blackening of cacao-pods in 

 the West Indies. The trouble is due to Phytophthora faberi, and the 

 pods are attacked when they are just about to ripen. The disease is 

 most prevalent in the damper districts which are subject to thick fogs, 

 and also during the rainy season. Preventive measures such as spraying 

 with Bordeaux mixture have proved very effective in checking the 

 disease. 



Paul A. Van des Bijl + describes the mischief done to apple-tree 

 branches and fruit by the fungus Goniothecium chomatosporum. On 

 branches it causes small dark specks which induce blisters in the bark. 

 On the apples it causes " russeting," producing a hardening of the 

 cells, so that when the apple swells cracks are produced in the skin. 

 Pruning and removal of all affected material is recommended, as also 

 spraying with Bordeaux mixture before the trees begin to bud. 



Ethel M. Doidge §has described a disease of potatoes in S. Africa due 

 to the fungus Vermicularia varians. It has also been found in Australia, 

 where MacAlpine gave it the name " black-dot disease," as suggesting 

 the typical appearance of the diseased tubers. The fungus appears just 

 before flowering, and the stems are then seen to be covered with minute 

 black dots which represent the sclerotia of the fungus, and are developed 

 in the tissue of the epidermis, through which they ultimately burst. The 

 stems attacked lose their fresh green colour, the leaves fall off, and 

 eventually the whole plant becomes brown and dry and quite brittle. If 

 the attack is late in the season, the tubers may not be seriously affected, 

 otherwise their growth is arrested, and they also may be diseased. 

 Burning of all the haulms affected is recommended. 



* Joum. Roy. Hort. Soc, xl. (1915) pp. 481-92 (7 pis.). 



t Bol. Seer. Agric, ix. (1914) pp. 213-6. See also Bull. Agric. In tell. Rome, vi. 

 (1915) pp. 312-3. 



\ Agric. Joum. South Africa, viii. (1914; pp. 64-7 (figs. 1-6). See also Bull. 

 Agric. Intel! Rome, vi. (1915) p. 313. 



§ Agric. Journ. South Africa, vii. (1914) pp. 879-82 (1 pi.). See also Bull. 

 Agric. Intell. Rome, vi. (1915) pp. 470-2. 



