256 TIMOTHY RICHAUDS LEWIS. 



Oral aperture to end of cesophagus . . ^^ of axi inch, or '45 mm. 



Diameter of oral aperture . . _ . . soVo " » '^^^ >> 



Width of extreme end (anterior) " . . -gyy „ „ 'Oi7 ,, 



Ditto anterior end at " neck " . . -^^ „ „ '04:5 „ 



Ditto opposite junction of intestine with 



oesophagus ...... ^^ ,, „ '112 „ 



Ditto about 5 inch from anterior end . yi-g- „ „ '102 „ 



Width where packed with ova and embryos ^00 " » '^^ " 



Width of uterine tube filled with ova ^22 » " '^^'^ " 



Ditto alimentary tube . . . ^^ „ „ '037 „ 



The ova do uot possess any distinctly marked '' shell ;'^ from 

 the smallest to the largest nothing but a delicate pellicle can be 

 distinguished as enveloping the embryo in all its stages; conse- 

 quently the form assumed by the ovum depends to a great extent 

 on the degree of the surrounding pressure. In fig. 3 (Plate XIIj 

 ova of various shapes are depicted (spherical^ triangular, oval), 

 and with a considerable latitude as to size. The average of six 

 measurements of the less advanced kinds of ova, /. e. those in 

 which the outline of the embryo was not distinctly evident 

 = tjVt" ('018 mm.) by tttVt," ("012 mm.) ; whilst the average 

 measurements of three ova in which the embrvos were visible 

 = ,i^" (-037 mm.) by ^0" (-030 mm.). 



When the latter, after having arrived at this stage of deve- 

 lopment, are examined during life, it is in many instances diffi- 

 cult to state whether they are to be considered as freed embryos 

 or not, as the " egg-shell^' has become so extremely attenuated 

 and translucent as only with difficulty to be distinguished. By 

 pressing the covering glass firmly the sac may often be ruptured. 

 It, however, appears probable that, even when the embryo 

 acquires worm-like appearances, the envelope is not lost in this 

 species so long as it continues in the blood. 



It is of importance to bear this in mind, as, contrary to what 

 is seen with regard to the nematoid haematozoa of dogs, the 

 embryos in the blood of man are each contained in a translucent 

 coecal tube. This tube is readily recognisable during life when- 

 ever the embryos can be properly observed in fresh clear serum, 

 as also in spirit-preserved preparations. I possess at the present 

 time specimens thus preserved of both species, one being con- 

 tained in blood removed from the heart of a person, who during 

 life, was known to harbour heematozoa, and the other obtained 

 from the blood-vessels of a dog similarly affected. In not a 

 single instance have I been able to distinguisli the least trace of 

 an enveloping tube in the latter, whereas in the former this tube 

 can be clearly demonstrated in the majority of instances. Hence, 

 notwithstanding their almost complete accord as to dimensions, 

 the character just referred to is sufficient to distinguish slides 

 prepared from either of these two specimens. A Uke distinction 



