528 JOHNSON. [Vol. VIII. 



evidently formed from the ectoplasm, as it has the dense 

 consistency of that layer and contains abundant pigment. 

 At the time of interchange of the micronuclear spindles, an 

 opening must, of course, be formed in the plate. 



The behavior of the gametes shows little that is character- 

 istic. They much prefer to remain fixed in one spot, when 

 they become moderately extended, and stand at a wide angle 

 to each other, the attitude being strongly suggestive of an 

 effort to pull apart. If disturbed, the gametes swim easily, 

 rotating about the long axis in precisely the same manner as 

 the individual Stentor ; if there is considerable difference in 

 size, the larger gamete fairly carries the smaller about. The 

 attachment of the gametes is very firm ; not only is it main- 

 tained during their violent contractions, but they can be 

 sucked up into a pipette without danger of separation. 



As in case of 5. ccsruleus, I have only once observed the 

 conjugation of 5. igneus. In July, 1891, I found a few 

 conjugated pairs at Wood's Holl, at different times from 

 the 17th to the 25th. As usual, the gametes were of 

 small size (in one instance of the variety nigricans), and 

 nearly all showed a notable development of red pigment 

 in the anterior part of the body. The manner of union and 

 relative position of gametes does not differ from that of other 

 Stentors, but the area of attachment is proportionally greater 

 than in S. ccendeiis. 



hhiclcar Phenomena. — Something of the internal processes 

 of conjugation can be seen in the living specimen. Such 

 observations are greatly facilitated by the absence of food- 

 vacuoles. 



One of the most noticeable changes of those observable in 

 the living animal is the separation of the nodes of the mega- 

 nucleus. This occurs very early in the process of conjuga- 

 tion. It is obviously brought about by rupture of the 

 commissures, which, as in division, are promptly resorbed 

 by the nodes. The latter then become perfectly spherical. 

 Their structure undergoes no change at this time, and their 

 affinity for stains is as strong as ever. After separation the 

 nodes leave their place in the peripheral portion of the endo- 



