174 oxyuris-larvjB hatched in the human stomach, 



normal. The shells did not become dissolved, though they all 



became somewhat rounder (i.e., wider and shorter) and thinner. 



In neither of the experiments two and three did I notice the 



pores scattered here and there over the whole surface of the egg 



as was the case when I subjected some eggs to the action of 



ai'tificially prepared digestive fluids.* 



The larvae are of the form shown in Fig. 2. The average 



length is 0-155 mm, ; the bottom of the mouth cavity or pharynx 



is discant 17^, the ner\^e-ring 12-4%, the pjsterior end of the 



cesophagus 33 17o> ^nd the anus 784% of the length of the 



animal from the anterior extremity ; the diameter opposite the 



base of the pharyux is equal to S°/^, opposite the nerve-ring to 



Q'Q°lo, opposite 'the posterior end of the cesophagus to 6-87o> 



opposite the middle of the body to 5-7°/o, and at the anus to 



3*27o of the entire length of the animal, dimensions which may 



be conveniently expressed by the formula 



1 12-4 331 M 784 

 -115 



3- 6-6 6-8 5-7 3-2 



in which the figures above the line represent lengths and those 

 below the line represent corresponding diameters, expressed in 

 such a manner that the unit of measurement is one per cent, of the 

 entire length, f The porus excretorius is situated 31-2 7o of the 

 length from the anterior extremity. The head is rounded, the 

 tail conoid. I believe that the sexes are already distinguishable 

 and that Fig. 2 represents a male. The females diminish in 

 diameter very uniformly from the oesophagus backward, while the 

 males have the tail contrasted by a sudden decrease in diameter in 

 the preanal region as is shown in the figure.* 



* The eggs used in those experiments were obtained in Germany, where 

 I was then residing, while those for experiments two and three here 

 described were obtained from Australian subjects, facts which may possibly 

 account for the difference. 



t A method of expressing the dimensions of Nematode worms which I 

 have found extremely convenient, the formula recording in itself sometimes 

 all that is necessary to characterize the species. 



* If this distinction between the sexes holds good, it follows as a corollary, 

 according to my observations, that the sexes are born in about equal 

 numbers. I made no count, but no great inequality could have existed 

 without my noticing it. 



