ROOT KNOT IN THE TOMATO. 53 



becomes a nest of very numerous eggs. There is thus no layin^^ 

 of eggs at the rate of lO to 15 per day as described in the Ameri- 

 can species. The eggs are oval at both ends, with straight sides, 

 and about 70 to 80 fi long, never 90 fi, and about two and a half 

 times longer than wide. 1 have never found any slightly curved. 

 At first they show granular contents with a clear cell wall, but 

 soon the young worm can be seen coiled up inside, each worm 

 having three bends. In most Nematodes of this type this con- 

 dition is the larval stage, the egg having developed a kind of 

 mouth at one end, but in this worm, as stated above, there appears 

 to be no larval stage, the eggs developing directly into the young 

 worms. All the eggs hatch at about the same time, so that some 

 nests show a squirming mass of young worms. After hatching, 

 the worms appear to increase very little in size, and certainly no 

 moulting stages have been observed. At this stage the gall begins 

 tu rot away, so that the young worms and probably eggs them- 

 selves are set free into the neighbouring parenchyma and soil, 

 and in this way other plants may become infected. It is possible 

 that the worms actually live in the soil as well as in the plant, and 

 only enter the plant for hatching or breeding purposes. The 

 swellings on the roots would thus be true galls. Most of the 

 worms seen in a gall would therefore have been bred on the 

 plant, and more galls are produced by further breeding. The 

 galls are probably not produced until the females begin to take up 

 their permanent positions. That is why some infected i^lants have 

 no galls on the roots. Infectioi'i obviously takes place in the first 

 instance from the soil, so that the eggs and even the worms them- 

 selves must have great powers of endurance. I have had some 

 infected plants under observation which I have just kept alive 

 through the winter. I have repeatedly found the worm present 

 on the roots but no sign of galls. It is difficult to decide upon 

 the kind of injur}' effected by the worm, as I have many plants 

 in the last stages of attack without any sign of galls. From 

 infected roots kept in water for three weeks living worms have 

 been obtained, as also after repeated drying and wetting. I have 

 had the pest under observation now for nearly two years, and 

 have not yet succeeded in infecting other plants, although the 

 pest has been recorded from South Africa as occurring on Celery, 

 Lettuce, Radish, Potato, and some others. 



WeSTPHAL'S Comet. — The periodic comet first dis- 

 covered by W'estphal, in 1852, was found on September 26th by 

 Delavan at La Plata, and was then about the eighth magnitude. 

 Its perihelion occurs on November 26th, and on December 3rd 

 its right ascension will be 20 h. 38' 16", and its north declination 

 42° 33'. That is to say, it will be in the neighbourhood of 

 a Cgyni, moving in a northerly direction. It is expected to be 

 faintly visible to the naked eye at perihelion. The period of 

 revolution of this comet is 61.12 years. 



