The Second Ecdysis of the Infective Larvae of Certain Trichostrongylidae in Solutions of Sodium Sulphide and of Organic Compounds containing Sulphur

Extract

1. The second ecdysis of infective nematode larvae readily occurs in watery infusions of chopped up garlic bulbs and the cast sheaths are dissolved after the larvae have left them. No particular change in the sheaths was observed before the ecdyses occurred.

2. Ecdyses also occurred readily in 1% sodium sulphide in distilled water, the sheaths being, however, remarkably distended and thinned before the ecdysis occurred.

3. In 0·1% solutions of cystein hydrochloride ecdyses occurred with changes in the sheath similar to those recorded by the writer in mixtures of HCl and NaOH and leading to detachment of a cap, but with little distension or thinning of the sheaths. The cast sheaths were usually not dissolved. Similar ecdyses occurred in 1% sodium taurocholate and 1% saccharin in distilled water, but the former of these two solutions seemed more toxic to the larvae than either saccharin or cystein hydrochloride.

4. Some ecdyses occurred in 0·2% sulphonal with detachment of a cap and some osmotic distension and thinning of the sheaths. The empty sheaths were all slowly dissolved in the medium.

5. In 1% sodium thiosulphate a few ecdyses occurred with some thinning and distension of the sheaths, but the larvae were usually shrunken and often died quickly.

6. The solutions here described could be used for artificial production of ecdyses, 1% sodium sulphide being probably the best for this purpose; but none are so useful as the 1 in 20 dilution of Milton hypochlorite used by the writer (1933 b), because this also sterilises the exsheathed larvae and the medium in which they exsheath.