292 XATHAX FASTEN. 



and vacuoles in the nuclear cup making it become more homo- 

 geneously green. Also the secondary vesicle shrinks somewhat, 

 thereby leaving the clear primary vesicle to show more prom- 

 inently (Fig. 25). An M/i6 KC1 solution produces swelling 

 and explosion of the spermatozoa (Fig. 26). In many instances 

 the explosion is so violent that the nuclear cup ruptures com- 

 pletely. 



6. Potassium Nitrate. -An M/2 KNO 3 solution which is iso- 

 tonic with sea water does not produce any explosion. However, 

 the protoplasmic cup swells and becomes more homogeneous 

 in appearance. Also the primary and secondary vesicles become 

 more distinctly marked off from each other (Fig. 27). An M/4 

 KNO 3 mixture has a similar effect. An M/8 KNO 3 solution 

 brings about a swelling of the protoplasmic cup and a slow ever- 

 sion of the second vesicle so that the spermatozoa resemble 

 Fig. 28. In an M/i6 KNO 3 solution the spermatozoa explode 

 very rapidly and they come to look like Fig. 26. 



7. Potassium Hydroxide. Very dilute solutions of KOH bring 

 forth a violent reaction in the spermatozoa. The protoplasmic 

 cup swells, becomes homogeneous and at the same time pushes 

 the vesicles upward (Figs. 29-31). The secondary vesicle under- 

 goes a rotation and is pushed to one side. Finally the vesicles 

 explode with great violence and the entire spermatozoon soon 

 goes to pieces. 



8. Distilled Water. Distilled water produces a rapid eversion 

 of the vesicles so that in a very short time the spermatozoa come 

 to resemble Figs. 32 and 33. 



9. Cane Sugar. -From the above experiments two conclusions 

 might be inferred regarding the explosion of the spermatozoa, 

 one is that it is due to lack of electrolytes, and the other is that 

 the explosion is due to a reduction of the osmotic pressure pro- 

 duced by surrounding the spermatozoa with a hypotonic solution. 

 In order to determine which factor we have to deal with, the 

 spermatozoa were surrounded with an M/i cane sugar solution 

 which is approximately iso tonic with sea water. If the factor 

 involved were due to lack of electrolytes then, since the sugar 

 solution contains no electrolytes, the spermatozoa ought to 

 explode. But the M/i cane sugar solution did not produce any 



