T. GOODEY 



35 



of the use of animal charcoal. The next cultures were therefore put up 

 with a liberal admixture of this substance with the teased-up droppings 

 so that a moist, not sloppy, medium was finally obtained. This was put 

 into Petri dishes, a shallow layer in each, and the lid of each dish was 

 provided, as before, with clean, moist blotting-paper. The dishes were 

 incubated at 22° C. 



From these cultures large numbers of ensheathed larvae of both 

 G. strigosum and T. retorlaeformis were obtained in the course of six days. 



The development of the larvae is in every way similar to that of 

 Ancylostoma duodenale described by Looss(4) and of Haemonchus con- 

 tortus described by Veglia(9). 



Fig. 1. Tails of ensheathed larvae of A. Oraphidiwn strigosum, B. TrirhostroTtqylus 

 retortaeformis. x 350. 



On the hatching of the egg a typical rhabditiform larva is produced, 

 having a buccal cavity, the walls of which appear under the microscope 

 as two refractive rods followed by two dots. This is followed by the 

 oesophagus which, for the greater part of its length, is somewhat cigar- 

 shaped, and is then constricted into a much narrower portion, and finally 

 swells out into a bulb within which can be seen the characteristic 

 Y-shaped lining. The intestine succeeds the bulb and presents a wavy 

 outline amidst the granular contents of the intestinal cells and terminates 

 in the anus. After the first ecdysis the larva grows and the oesophagus 

 loses its original appearance, becoming longer and without such pro- 

 nounced demarcation into distinct regions. The posterior bulbous portion 

 seems to become elongated and at the same time flattened. The cells 



