92 FUNGOID PESTS OF CULTIVATED PLANTS. 



partitions into four cells, which remain for a long time attached to each 

 other, but ultimately separate and each segment becomes practically a 

 separate germ cell. Sometimes each of the four cells will commence 

 germination while still attached to each other, but will ultimately fall 

 away, and each cell, now almost quadrangular, will when free assume 

 gradually a spherical shape. They do not always germinate at once, but 

 seem to be capable of an interval of rest of from two to three months. 

 Germination proceeds rapidly, and may be completed in six hours. The 

 mycelium has a putrefactive action, breaking up the cells of the host and 

 hastening decay. 



Known in Belgium, Italy, and North America. 



Sacc. Syll. iv. 3386; Smith, Field Crops, p. 32, figs. 10, 11 ; Mass 

 Dis. PI. 333, 442 ; Cooke, Hdbk. No. 1870 ; Journ. E.H.S. xxix. 1904 

 p. 141, figs. 27, 28 ; xxix. 1905, p. 873. 



POTATO SCAB. 

 Sorosporium Scabies (Fisch.). 



Nearly fifty years since Berkeley called the attention of the Horti- 

 cultural Society to one of the causes of scab in Potatos, under the name 

 of Tubercinia Scabies. But it was probably known to Martius three years 

 previously. 



There are some even now who think that Berkeley made a mistake. 

 He attributed the fungus to be closely allied to the smuts, and described 

 it as consisting of globose bodies, composed of minute cells, in such a 

 manner as to form a hollow globe, with one or more lateral openings. 



" The fungus grows beneath the cortex of the tuber, where it forms a 

 thin dark greenish-brown stratum, often extending over the greater part 

 of the external surface of the tuber." 



It is said that no trace of the fungus is often to be seen at the time of 

 harvesting, but frequently shows itself during winter in stored Potatos 

 which on digging appeared to be quite sound. In bad cases discoloured 

 spots first appear, and these increase in size and become confluent until 

 at length the entire skin is discoloured. Then the cuticle bursts and the 

 spores are set free. 



We have ourselves met with such scabbed Potatos in greengrocers' 

 shops, and obtained from them the hollow bodies described by Berkeley, 

 the existence of which has been called in question. 



Berk. Journ. E.H.S. 1846, p. 33, figs. 30, 31 ; Sacc. Syll. vii. ; Smith, 

 Field Crops, 35 ; Mass. PL Dis. 225 ; Cooke, Hdbk. No. 1536 ; Plowr. 

 Brit. Ured. 294 ; Journ. E.H.S. xxix. 1904, p. 145. 



American Potato scab caused by Oospora Scabies is quite a distinct 

 thing. Mass. PI. Dis. p. 299. 



POTATO TUMOUE. 

 (Edomyces leproides (Trabut.). 



This disease made its appearance in this country in 1901, when a 

 whole crop of Potatos was destroyed by its ravages, and it has since 



