FREE-LIVING NEMATODES 



461 



outnumber them; and the number of free-Uving individuals is 

 so great that they probably constitute one of the important 

 mechanical as well as biological factors in soil, and in the bot- 



Lip , 



Lateral field 

 Pharyngeal bulb 



Pharynx , 



Salirary gland 

 Muscular layer 



Cuticula 



Hair 



Esophagus 



Cuticula 



Nerve-ring 



Duct of ventral gland 



Esophagus. 



Nerve ring 



Ridge in cuticula 



Esophagus 



Stria of cuticula 



Sub- cuticula 



Wing of cuticula 



Cuticula 



Cardiac bulb ... 

 Dorsal field 



Valvular apparatus 

 Its radial muscles 

 Muscular layer 

 Wall of intestine 

 Wing of cuticula 

 Ovum fit to fertilize 



29. Blind end ovary 



30. Intestine 



31. Yolk of egg 



32. Nucleus of egg 



33. Shellofegg... 



34. Internal lateral field ,. 



35. External lateral field 



36. Intestine 



37. Copulatory muscle 



38. Wing of cuticula. 



39. Copulatory muscle 



40. Intestinal cell 



41. Accessory male organ 



42. Ejaculatory duct 



43. Copulatory muscle 



44. Wmg of cuticula 



45. Constriction in spiculum 



46. Right-hand spiculum 



47. Distal end spiculum 



48. Accessory piece 



49. Caudal gland . . . . 

 60 Left wing of bursa 



61. 1st caudal gland 



62. 2nd caudal gland 



63. 3rd caudal gland 



64. Muscular wall 



56. Right wing of bursa 



. Cephalic seta 

 . Labial papilla 

 , Pharyngeal rib 

 . Pharynx or throat 

 . Pharyngeal tooth 

 . Pharyngeal bulb 

 . Salivary gland 

 . Lateral organ 

 , Esophagus tube 



Eye, with lens 

 , Excretory pore 

 . Ampulla 

 . Median bulb 

 . Nerve-rmg 



Ganglion cells 

 , Duct of ventral gland 

 . Duct of lateral gland 



A lateral gland 



Cardiac bulb 



Valvular apparatus 

 , Wing or ridge in skin 



Cardiac coUum 



Cardia 



Stomach or intestine 



Tessellation of same 



Cuticula 



Wall of intestine 



Ventral gland 



Striation in cuticula 



Ripe ovum 



Uterus 



Unripe ovum in ovary 



Spermatoioa 



Fertilised egg in uterus 



Blind end of ovary 



Yolk of egg 



Vaginal glund 



Vulva 



Vagina 



Vaginal gland 



Lateral field 



Seminal vesicle 



Wall of same 



Spermatozoa 



Copulatory muscle 



Accessory male organ 



Ductus ejaculatoriuB 



Three pre-anal papillao 



Copulatory muscle 



Proximal end spiculum 



Pylorus 



Anterior ribs of bursa 



Anal gland 



Anus 



Post anal papillae 



Caudal gland 



Median ribs of bursa 



ursa 

 Posterior ritis of bursa 

 Duct ofraudul glandt 

 Terminus 



Diagram of Nematode structure. 



Fig. 766. 

 Above, anterior end of female. Below posterior end of male. 

 (After Cobb.) 



toms of lakes and oceans. The aquatic nematode species exist 

 in enormous numbers, in both fresh and salt water, while tlic 

 number of individuals is past computation. The unavoidable con- 



