•2'2 S(i'jn-(/it«(it>i vdiiKcd bij I Ik h'tin'onii 



in till' biutal t-avitv. It is usually assuiiu'd that it is by means of this 

 organ that it pierces plant tissues and then penetrates into the plant, 

 and that havinj^ once got inside it uses its stylet to puncture the cells 

 amongst which it is l^-ing. and feeds on the cell sap which it sucks out 

 from them. 



All this, however, needs much further investigation, I think, especially 

 when one remembers the power pos.sessed by the infective larvae of the 

 human ])arasite Anoi/losloma dmxJenale of boring through the skin without 

 the aid of anv piercing mouth armature. Moreover, no one. as far as 

 1 know, has ever obser\'ed the stylet of Tifletichus dipsaci in use as a 

 piercing organ. It is a very small structure, being 12-15 microns in 

 length, and t he point is so fine that it can only be seen under the very high 

 magnification of an oil-immersion lens. In all my numerous examinations 

 of diseased clover i>lants. l)oth fresh and ])reserved. 1 have never found 

 the stylet exserted from the anterior end of the body. 



Another point: it is a matter of observation that the parasite, in .some 

 way or other as }et not understood, causes an increase in the size of 

 parenchymatous cells of the host plant, and this also requires further 

 investigation. Kitzema-Bos suggested that it was due to a secretion 

 poured out by the worm, and considered the spatulate posterior portion 

 of the oesophagus as probably the seat of the secreting gland; the matter 

 is, however, still very obscure. It is hoped that later on one may be 

 enabled to take up the elucidation of these interesting problems. 



DESCKll'TlON OF THE DISEASE. 



In regard to a suitable name for this disease, the term Sicni (/i.va/.ve 

 sliould be used, thus keeping in line with the German expression >Slock- 

 krankheit for the same condition. 'Die term Stem-rot is already in use 

 as the name of tlie fungal disease of clover caused by Sclerotinia Iri- 

 folioniin, see Anu)s (1919) and Cotton (1920). 



Admittedly the two names are sufficiently alike to lead to the ])ossi- 

 biiity of confusion in nomenclature for two very different pathological 

 conditions, but 1 would suggest that the confusion might be avoided by 

 the use of another name for the fungal disease which is not strictly con- 

 fined to the stem as is the eelworm disease, but attacks the whole of the 

 foliage of the plant. 



The term Foliw/e-rol of clurcr. or Clorer rot would be j)referable to 

 Stem-rot, which is not an exact descriptive designation. It is of interest 

 to note that the Germans have avoided confusion by the use of the word 

 Klcekrebu for the fungal tlisease. 



