lOi WILLIAM BLAXLAND BENHAM. 



epithelium passes across these layers and meets the cuticle 

 round the edge of the pore. There is a special set of muscle- 

 bundles, forming a sphincter muscle for the pore. 



As to the physiology of the pore, Ude considers that 

 there is not the slightest connection between the dorsal 

 pore and the nephridia, although the former is, to a certain • 

 extent, excretory, since the coelomic fluid can be extruded 

 through it, either in drops, as in Lumbricus, or may be even 

 squirted through the pore to a distance of about a foot, as 

 has been noticed in species of Megascolex and Perichseta 

 by Vordermann ('Natwork. Tijdsche-Nederl. Indie,' vol. ii, 

 p. 111). 



The following experiments were undertaken to ascertain 

 whether or not any liquid was taken in through the pore. A 

 worm was dried by lying on blotting paper for some hours; the 

 anterior and posterior extremities were then tied with string 

 and the worm was immersed for fifteen minutes in water. On 

 removal it was found to be greatly swollen, and Ude was led to 

 think, from this, that water was taken in through the pore. 

 But the following experiment caused him to doubt the truth 

 of this opinion. Instead of employing pure water he dissolved 

 some iron oxide in the water, and after the worm had remained 

 in this for some time (after previously being dried) it was 

 killed and the ccelomic fluid was tested for iron by means of 

 cyanide of potassium. No red colour was produced, and hence 

 Ude concludes that no water was taken in through the dorsal 

 pore. The swelling of the worm must therefore have been due 

 to the intaking of water by the genital ducts, nephridia, and 

 mouth. The worm was carefully weighed before and after the 

 various stages of the experiment, and it was found that it 

 weighed about 0'2 grams more (on the average) after immer- 

 sion than before. 



Accompanying this memoir is a bibliography of the subject, 

 and a useful table for determining the species of the genera 

 Lumbricus and Allolobophora is given. The position of 

 the first dorsal pore is given in each species, and appears to 

 furnish a useful specific character. 



