290 Naohide Tatsii. 



55 per cent sol. of CaCU ( = 5 m. CaCl,)^ I part. 



Sea-water 9 parts. 



The two solutions found to be the next best were: 



14.6 per cent of NaCl ( = -," m. NaCl) i part. 



Sea-water 2 parts. 



18.6 per cent of KCl ( = ''■'- m. KCl) i part. 



Sea-water 2 parts. 



It may be stated that there are only slight differences in action of 

 these three solutions, while that of MgCh solution is totally different 

 from the others. 



The precautions taken against accidental contamination of the 

 eggs with spermatozoa were as follows: Sea-water was first 

 heated to 80° C. for twenty minutes, cooled down to the original 

 temperature (20° C.) and wxU-water was added to make up the 

 loss by evaporation. The bottle containing the water thus steril- 

 ized was aerated by violent shaking. The female worms were 

 kept for two days in an aquarium separate from the males. To 

 obtain the eggs for experiment a piece about an inch long was cut 

 out of a ripe female with a pair of sterilized scissors and was sub- 

 merged in fresh water for five minutes. After that the piece was 

 washed with sterilized sea-water to get rid of the eggs, which had 

 been squeezed out in fresh water, since the eggs thus discharged 

 might have undergone some pathological changes. The piece 

 thus treated w^as chopped up with a pair of scissors sterilized with 

 fresh water. Of course, all the dishes used for experiment were 

 washed with fresh water. 



For each experiment with the cytasters two lots of eggs from 

 the same piece were used as controls to see if the particular lots 

 of eggs were healthy. 



A. One lot of eggs was examined after five hours' sojourn in 

 the sterilized sea-water. Most of them were at the metaphase of 

 the first maturation mitosis, while in a few ego-s the o-erminal 

 vesicle was found intact. 



B. The other lot of eggs was mixed with sperm-water ten 

 mmutes after release. Fertilization and subsequent development 

 took place normally as in those eggs kept in ordinary sea-water. 



'Drv' cn'stals dissolved in well water. 



