NOTES ON PARASITES. 449 



These four cells lie on the same level as the lateral ex- 

 cretory canals, two anterior and two posterior, but all lie in 

 the anterior third of the animal. The cells are very large, 

 in A. megalocephala attaining a length of 1 cm. and in A. 

 hunbricoides of 3 mm. Each contains an enormous nucleus 

 — so large as to be visible to the naked eye — and each 

 breaks up peripherally into a meshwork of fibrils which 

 attach themselves to the lateral lines, to the exterior of the 

 alimentary canal and to the muscle-cells of the body wall. 

 (Fig. II.*) 



The branching fibrils which run from the body of the 

 cell to the neighbouring organs are coated with numerous 

 spherical or pyriform bodies (Figs. II. h. and III. b.) in each 

 of which Nasonow recognises a nucleus, in fact he regards 

 them as minute cells attached not only to the fibrils but to 

 the body of the giant cell. When carmine or Indian ink is 



Fig. 3. — The end of two fibrils of the giant cell. From Nasonov. 



a. The fibril. 



b. The phagocytic cells. 



injected into the body of the Nematode, the granules are 

 taken up by these minute cells and accumulating around 

 the fibrils and body of the giant cell render it visible even 

 to the naked eye. In the same way they take up the bacilli 

 of Anthrax or Tubercle bacilli and within their body these 

 foreign germs are disintegrated and destroyed. Injection of 

 appropriate reagents demonstrate that the reaction of these 

 cells is an acid one. When kept at a temperature which 

 does not materially differ from that of their host, and the 

 giant cell is observed alive, it is seen that the minute cellules 

 which surround it are capable of amoeboid movements which 

 no doubt assist in the ingestion of foreign particles. 



We have, then, in the body-cavity of Nematodes at two 

 different levels, a sieve consisting of two giant cells with 

 processes spreading across the lumen of the space, and 



