146 AGRICULTURAL RESEARCH AND THE FARMER : 



animal, may yet be active in its larval stage and cause injury. 

 This point is regarded as of sufficient importance to justify an 

 extended inquiry. 



The study of two round-worm parasites of poultry, namely, 

 Hcterakis and Syngamus, has also been carried out during the 

 last two years. Heterakis lives in the intestines of fowls. The 

 complete life history has been worked out. The eggs pass out 

 with the faeces, and hatch in about a fortnight. The iarvse 

 become adult in about three weeks. They do not feed outside 

 the body, so that there is no fear of skin infection, and if the 

 faeces are removed, so will be the sources of infection. Syngamus 

 is the cause of " gapes " in poultry. The eggs (which hatch 

 outside the hen) are infective after about two days for three 

 months. The worm may become adult in the body in 14 days 

 after infection. 



Tylenchus (Eelworm) in Clover. — This investigation was 

 carried out at Rothamsted before the worker was transferred 

 from that institution to the London School of Tropical Medicine. 

 Tylenchus is an eelworm which attacks clover plants and is 

 responsible for one form of clover " sickness." The plants 

 are attacked either in the seedling stage or later, the eelworm 

 causing swelling in the stems and a curious twist of the leaves. 

 The disease has been known for many years in this country, 

 and various methods of prevention have been recommended, 

 such as deep ploughing, treatment with potash, salts, &c., but 

 only as possible remedies. It has been recognised that some 

 clovers are more Hable to attack than others, and the object 

 of the investigation was to see if clovers could be classified 

 according to their susceptibility to attack, so that if a farmer 

 knows that eelworm is present in the soil he may avoid sowing 

 a highly-susceptible clover. The classification would also be 

 useful in breeding clovers immune from the disease. One 

 hundred seeds of different varieties of clover were therefore sown 

 in pots of highly infective soil and grown under exactly similar 

 conditions as regards temperature, moisture, &c. The extent 

 of attack was very carefully estimated. It was found that the 

 red clovers of all nationaUties, and kidney vetch were highly 

 susceptible to the disease; the alsike clovers were very much 

 less susceptible; the white clovers were only lightly attacked. 

 A fourth group, comprising lucerne, trefoil and one kind of white 

 clover, was not attacked at all. While these results are very 

 significant, it must be remembered that they represent only one 

 season's work, and require confirmation before they can be 

 regarded as established. 



