A NEW FRESH- WATER NEMERTlNE. 



251 



that freshly deposited eggs were found in mornings (6 to 8 a.m.) al- 

 ways in so early a stage of segmentation as consist of 2 or 4 cells, 

 it may be assumed that the deposition took place before dawn. I 

 should here mention that the eggs segment very slowly, some forty 

 to sixty minutes being required for one complete cell-division in early 

 cleavages. 



Individuals of a large size lay 400 to 500 eggs in all. The eggs 

 are found sometimes scattered about without order on the bottom of 

 the vessel, and sometimes in a group, as described by Lebedinsky 

 (1897) for Tetrastemma vermiculiis, enclosed in a colourless and 

 transparent jelly-like string 4 to 5 cm. long and about 2 mm. thick. 

 This gelatinous, substance, probably mucin in nature, gradually 

 grows more liquid-like with the lapse of time, and finally, within 48 

 hours, is thrown off by the developing embryos. 



As far as my observations go, the mother worm perishes sooner 

 or later after spawning. Those individuals which have finished 

 spawning can easily be recognized by their loss of the peculiar 

 yellowish markings which were visible before on the dorsal side, 

 by their dirty brownish red colour, and by their showing 1111- 

 evenness of body-surface. In spite of my attempts to keep alive 

 such individuals by feeding they invariably broke up into 

 short pieces within one or two days finally to become 

 totally disintegrated. To my regret I could not ascertain if the 

 same or a similar fate befall the precociously mature worms after 

 spawning. 



Lastly I may be allowed to make a few remarks regarding the 

 segmentation of the eggs. As the segmentation of nemertine eggs is 

 but meagrely known to us, I have endeavoured to study the process 

 with the material in hand and, if possible, to make out the origin of 

 mesoderm-cells. To my regret, shortage of material has compelled 



I) Lebedinsky, J., Beobachtung über die Entwicklungsgeschichte der Nemertinen. 

 Archiv, f. Mikr. Anat., Bd., 49, 1897. 



