GRAMINEOUS CROPS. 119 



ordinary farmer as sucli. If a small portion of this 

 cottony-looking substance is placed in a drop of water, 

 and examined under the microscope, it will be seen that 

 there are a number of minute worms, which twist and 

 wriggle about in the most excited manner. No sooner 

 does the moisture dry up than they at once become in- 

 active, and remain dormant until again supplied with 

 water. These small nematoids are capable of being dried 

 and revived many times before they are killed. " They 

 have the extraordinary faculty of retaining vitality for 

 many years, even though they are perfectly desiccated. 

 Four or five years is by no means an uncommon duration 

 of life in such conditions." Mr. W. Carruthers, F.R.S., 

 states " that vitality was restored in some eelworms (of a 

 different species) after they had been in the botanical 

 department of the British Museum for more than thirty 

 years." ^ A fully grown Tylenchus tritici is about the 

 one-sixth of an inch ia length. The sexes are separate, 

 and pairing takes place within the host-plants, where 

 large numbers of microscopic eggs are deposited. These 

 eggs are hatched in about fourteen days, and quickly 

 grow into the cotton-like masses previously described. 

 T. tritici infests also oats, rye, maize, and certain grasses.^ 

 These nematoids are propagated to an unlimited extent 

 when a few ear-cockle grains are sown among seed-wheat. 

 It has already been stated that these "worms " are capable 

 of being desiccated without losing their vitality ; and 

 when the surroundings are favourable, they travel through 



' See also Bastian's paper in the Transactions Linnean Society, 

 vol. XXV. 



2 Festuca elatior (tall fescue), Agrostis stolonifera (florin grass), 

 A grostis vulgaris (bent grass), etc. 



