244 



I. IK EDA : 



exact number of external openings of the excretory system. It may 

 however be stated that there exist more than one — very probably 

 three or four — openings on each side. 



The number of mature hermaphroditic gonads varies remarkably 

 With the different size of mature worms. As ascertained by rear- 

 ing up the embryos hatched from eggs, the worms enter early into 

 sexual maturity, even before completely acquiring the characteristic ap- 

 pearance of full-grown individuals. About two months after egg- 

 deposition, I found a number of small individuals which had developed 

 from the eggs, measuring scarcely over 10 mm. in length, but 

 already possessing about twenty pairs of fully developed gonads. All 

 these small worms were of a dark green colour, instead of being deep 

 yellowish red as in real adults. That they were precociously mature 

 individuals, is evident from the following facts (see figs. 4 and 5): the 

 parenchymatous tissue (.p. c.) is on the whole far less developed, the 

 nephridial canals (//<"/>//.) are less numerously branched, and the wall 

 of alimentary tube (int. and ocs.) less complicated in structure, than 

 in really full-grown individuals. Examining a complete series of sec- 

 tions of one such form, I have found about eighty pairs of gonads, of 

 which about twenty pairs may be said to have been mature and the 

 rest still immature. The mature gonads (see fig. 4) were in general 

 much smaller than those found in full-grown individuals, each of them 

 containing mostly only one and rarely two ripe eggs (<?. in fig. 4). 



In full-grown worms of yellowish red colour, there exist about 

 eighty pairs or more of ripe gonads, each containing three or four 

 egg-cells. These gonads, as also the precociously mature ones, are of 

 essentially the same structure as those described by previous observers 

 from St. eilhardi and 5/. gracense. This is also the case with the 

 immature gonads. Only I should emphasize one point with reference 

 to the hermaphroditism. After examining a fair number of the speci- 

 mens preserved during the breeding season, I have arrived at the 

 conclusion that in the present species both sorts of sex-cells come 



