CHANGES PRODUCED IN LUNG BY OLLULANUS TRICUSPIS. 149 



vesicles (d). The two masses a and b were originally distinct, 

 but they have gradually increased in size until they have 

 joined and formed practically one irregular mass. In the 

 air- vesicles around these nodules there is often to be found a 

 large number of catarrhal cells. 



If now we take one of the nodules seen in fig. 1 (b) and 

 examine it under obj. viii, oc. 3, Hartnack, we find it pre- 

 sents the appearances seen in fig. 3. Here we have four 

 capsules represented, one (a) empty, two {b, b) others contain 

 a finely granular mass slightly shrunk from the wall of the 

 capsule and representing the degenerated worm, and another 

 (c) gives the appearance of the worm as it exists coiled up 

 within its capsule. This shows that all the worms within 

 any individual mass do not reach the same stage of develop- 

 ment at the same time. The tissue surrounding and holding 

 all these capsules together is shown to be made up of a 

 branching and an anastomosing (d) network, giving rise to a 

 reticulated appearance, such as is seen in a lymphatic gland, 

 with here and there small masses (d) which appear like 

 nucleated branched cells whose branches anastomose with 

 the adjacent fibres of the reticulum. Within the mesh- 

 work are a number of nuclei which appear as if they were 

 free. These nuclei are specially well brought out by the 

 action of logwood. In some of the nodules this reticulated 

 tissue becomes much compressed near the circumference of 

 the nodule, as shown in fig. 2. 



In many nodules also there is often a considerable amount 

 of pigmentation, such as so frequently occurs in other diseases 

 of the lungs. 



Not unfrequently are. to be met with amongst this reti- 

 culum multinucleated masses of protoplasm which may be 

 termed giant cells, as seen in fig. 4, (a). They are granular 

 in appearance, contain a great number of nuclei, and give 

 off a series of processes which anastomose with the fibres of 

 the meshwork in which they lie. With regard to these 

 giant cells I propose to direct attention at another time. 



The outer portion of these nodules, where they project 

 into the air-vesicles, are covered by epithelium, which is in 

 some places proliferating, and the air vesicles adjoining pre- 

 sent all the appearances of catarrhal pneumonia. Many of 

 the catarrhal cells in those sections steeped in perosmic acid 

 are seen to be partially filled by granules blackened by this 

 reagent. These contained granules seem therefore to be of a 

 fatty nature. 



The distribution of these embryos in the lungs is entirely 

 confined to the vesicular structure, for if a section of the 



