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on the surface. Occasionally on rather long-dead specimens a sapro- 

 phytic fungus, such as Botryiis cinerea, was present. This absence of 

 any obvious cause for the disease led to a good deal of speculation. 

 Some writers have put it down to " physiological causes " (mean- 

 ing a disease due to errors in cultivation), and as will be seen with, at 

 least in part, good reason. Others ascribed it to bacterial attack, 

 probably on account of some of its symptoms being similar to those 

 seen in certain forms of bacterial disease in other plants. 



Later more complete specimens were sent to the -Laboratory, and as 

 the appearance of the plants previously sent in had suggested the possi- 

 bility of serious interference with the water supply at a critical period 

 of the plant's growth, careful examination was made of the roots. In 

 every case where the specimens were complete, and had been properly 

 packed, the fungus Thielavia hasicola was found present on the brown 

 patches already referred to on the roots. 



Unlike the two fungi discussed above, this is well known in Britain, 

 and is widely spread over the world. Berkeley and Broome''' were 

 the first to describe it in 1850. They found one form of it at the 

 base of stems of peas, and of Nemophila articulata, at King's Oliffe, 

 and named it Torula hasicola. This form has been met with from 

 time to time on a variety of plants, and is the most prevalent one 

 on sweet pea roots. The spores- are very dark chestnut-brown in 

 colour, and are produced in rows of five to seven, sometimes in single 

 rows, sometimes in a few such rows springing close together from 

 the mycelium which, at least at first, grows chiefly in the cortical 

 tissues of the root. These spores are very blunt, and of such a shape 

 that when still in the chains in which they are produced, no con- 

 striction marks the place where one spore joins its fellow\ A second 

 form of spore, oblong and colourless, is formed inside the ends of some 

 of the hyphse, but we have rarely met with this form on sweet peas; 

 and lastly a third form belonging to a higher type of fruit is to be met 

 with on dying or dead roots. We have found this stage quite frequently 

 on such roots. They are dark brown, different in shape from the dark 

 brown conidia, and produced in eight- spored asci in very fugitive 

 perithecia, which break to allow the escape of the spores. Zopf 

 described the last and highest form in 1876, and founded the genus 

 Thielavia\ to contain it, recognizing that it was the final stage in th^' 

 life history of the fungus Berkeley and Broome had described undeij 

 the name Torula hasicola, and therefore calling it Thielavia hasicola. i 



The conidial or Torula form of the fungus had been found by 

 Sorokin:|; in 1876 in Eussia, but he failed to recognize its identity with 

 Torula hasicola, and coined another name for it, calling it Helminthoi 

 sporium fragile. Saccardo also failed to identify it correctly whe: 



* M. J. Berkeley and C. E. Become. " Notices of British Fungi," And 

 and Mag. Nat. Hist. II., June 5, 1850, p. 461. 



t W. Zopf, in Sitzu/u/slir r. d. Botan. Ycr. d. Prov. Brandv/ihiirg, June 187i 

 p. 105. 



^ N. SoEOKiN. Ucdn.-1'jia (1876), p. 113. 



