ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 191 



wliether the tubes filled with pale soft contents which traverse the 

 central medulla of so many Annelids, are, or are not, all homologous 

 structures ; there can be no doubt that the tubular fibres of Holla 

 and Arabella are the same as the neural canals or giant fibres of the 

 Oligochseta ; but much still remains to be made out as to their connec- 

 tions with the cells and their function. This, however, is certain 

 that the Annelida, no less than the Arthropoda and the Vertebrata, 

 present marked variations in the size of their ganglion cells. Passing 

 to the peripheral nerves, the author demonstrates the circular 

 character of this system, which has already been detected in Sipun- 

 culus and Echiurus. A sympathetic system was found in longi- 

 tudinal sections of the body, when pale fibres were seen to be running 

 parallel to the ventral medulla, and apparently connected with it by 

 secondary ganglia. 



The greater part of the enteric canal is very simple, the only 

 complications being in the anterior region. A series of regular folds 

 are found behind the mouth, and project considerably into the lumen 

 of the tube ; their substance is mainly composed of muscle, and, as 

 compared with other Lumbriconereids, they are rudimentarily de- 

 veloped in Oligognaihus. After describing in detail the structure of 

 the jaws, the author refers to a canal which opens on the ventral 

 surface of the anterior portion of the enteron, and which he thinks, 

 though material has prevented from coming to a definite conclusion, 

 may be homologous with the secondary gut of the Capitellidae. 



The segmental organs present nothing specially worthy of note 

 here, and the reproductive organs were not matured in any specimen 

 examined. 



Development of Anguillnla stercoralis.* — Professor E. Perron cito 

 gives an account of his observations on the development of this 

 endoparasitic Nematode outside the human body. After a medical 

 history of a patient afflicted with this worm, and who, till he 

 went to work in the St. Gothard Tunnel, was remarkably healthy, 

 he states that he was able to convince himself that A. stercoralis may 

 be developed in the intestine of man, without the necessity of any 

 free-living larval stage. When the embryo leaves the egg it is 

 0*2 mm. long, and O'Ol mm. broad. The larv^ leave the body at 

 different stages of development ; and when cultivated at a tempera- 

 ture of from 22-25° C, do not all complete their development, or 

 become sexually mature. In what may be known as the second stage, 

 or that which is reached after sixteen or seventeen hours, they are 

 longer and more delicate, are enclosed in a delicate capsule, and the 

 stomach has lost its chitinous armature; they now have on the whole 

 a very close resemblance to the larvae of A. intestinalis. Those larvae 

 which attain the adult condition, retain the capsule till they attain 

 maturity ; they may become as much as -^ a mm. long. The sexes 

 are separate, and the female is about a third longer and broader than 

 the male, and contains about thirty eggs. 



After discussing the zoological relations of this helminth, 



* Journ. Anat. et Physiol. (Eobin) xvli. (1881) pp. 499-519 (1 pi.). 



