T. GooDEY 45 



capable of motility longer than the N. americanus larvae, and none of 

 them revived in water. I performed two tests for power of revival for 

 G. strigosum and T. retortaeformis larvae. In the first case I transferred 

 them to water after 1\ hours, i.e. after all motility had ceased, and then 

 two or three revived after 2 hours. In the second test I transferred them 

 to distilled water after 20 minutes in saline, i.e. after the period required 

 to bring all movement to an end in N. americanus larvae. In this case 

 all the larvae revived. 



Saturated solution of saline. This causes cessation of movement very 

 rapidly in all cases, and after transference to distilled water no N. ameri- 

 canus revived, but two of the others showed signs of movement. 



It is clear from the above that G. strigosum and T. retortaeformis 

 larvae are more resistant to the action of plasmolysing agents, and after 

 the action of such are more capable of revival than the larvae of 

 N. americanus. 



I conclude from these results that the sheath in the case of N. ameri- 

 canus larva is more permeable than that of G. strigosum and T. retortae- 

 formis and that the larva within is more easily injured by the withdrawal 

 of water from its tissues than in the case of the other two organisms. 



NATURE OF THE SHEATH. 



It has already been pointed out that the sheath of all ensheathed 

 larvae is produced by the replacement of the cuticle by the development 

 of a new one underneath. It is well known too that the cuticle of all 

 nematodes is composed of a very resistant substance capable of holding up 

 most fixing agents and rendering the staining of these organisms a very 

 difficult business. I decided therefore to carry out a few tests to obtain 

 if possible a little more information as to the nature and properties of 

 the sheath both in N. americanus, G. strigosum and T. refortaefortnis 

 larvae. 



Martin ((5) p. 101) quotes the results obtained by Lambinet and others 

 with the ensheathed larvae of Ancylostoma. Lambinet found that cor- 

 rosive sublimate 0-2 per cent, does not kill them, that 3 per cent, pheno- 

 salyl arrests their movements after 1^2 hours; Fernbach's liquor diluted 

 1 in 10 does not immobilise them after an hour; the pure liquor acts in 

 I hour. Five per cent, sulphuric acid kills after f hour; a saturated 

 solution of sodium bicarbonate does not kill after 2 hours, neither does 

 Eau de Javelle after 1 hour. Camphorated petrol seems to stimulate 

 their vitality; 3 per cent, lysol kills in 1 hour. Chloroform, ammonia and 

 carbon disulphide all kill within 24 hours; formol vapour does not kill 



