328 GRIFFIN. 



A process of this kind also suggests that a certaiu fuuctional independ- 

 ence of ectosarc and endosarc exists in spite of close structural relations. 

 The very definite and regular straeture of the ectosarc has been spoken 

 of in the fii-st part of this paper; the process of invagination (in which 

 the ectosarc chiefly is concerned) suggests that the relations of the 

 primary geiin layers of Metazoa may be quite definitely foreshadowed 

 in some of the higher Protozoa. 



Development of the neiv cirri (Plates VI, VII, and VIII, figures 35, 

 33, 33, 34, 35, and 36). — While the changes described in the foregoing 

 pages have been proceeding, a new complement of cirri is developed 

 for each half of the mother body, and all of the original cirri are absorbed. 

 The order in which these events occur is decidedly definite. In order 

 to follow the course of the new cirri we must distinguish each of the 

 cirri of the fully foimed body. The frontal cirri I have numbered in 

 figure 33, Plate VII, from 1 to 7; the ones usually called abdominal 

 cirri are numbered 8, 9 and 10; the anal cirri are I to V; the left mar- 

 ginal cirri are LI and L3, while the riglit marginal cirri are El, E3, and 

 R3. ^ 



At about the time that the meganucleus reaches the condition of 

 greatest condensation, ten slit-like, longitudinal depressions appear in two 

 rows of five each upon the ventral surface of the body. The two com- 

 plete rows appear simultaneously, and not successively, as Wallengren 

 observed in Euplotes harpa. 



The slits of the anterior row I have distinguished by the letters A, 

 B, C, D, and E; those of the posterior row by a, i, c, d, and e. By 

 combining these letters with the numbers of individual cirri, each cirrus, 

 its origin, and its course can be indicated. 



The slits are produced both by the solution of the pellicle and by 

 depressions of the ectosarc at those points. The places where the slits 

 appear are verj"- definite and subject to little variation, being always 

 practically the same as shown in Plate VII, figure 32. In this specimen 

 cirrus 7 occupied a position a little back of its usual one. It generally 

 stands to the right of the anterior end of slit A. (See Plate VI, figure 

 35.) It will be noticed that cirrus 9 stands between the posterior 'ends 

 of slits C and D, and also that slit E is widely separated from D, and, 

 rmlike the others of this row, points toward the edge instead of the center 

 of the body. It also is important to observe that slits a to e arise outside 

 of the depressions of the adult anal cirri. 



There is almost no difference between Euplotes worcesteii and B. harpa 

 in the points at which these slits appear. The only considerable differ- 

 ence in the origin of any of the cirri is in the case of the cirrus named 

 F by me, and I-l by "Wallengren. This cirrus arises much farther for- 

 ward in E. harpa than in E. worcesteri; the arrangement in E. harpa is 

 such that there is much less difference in the origin of I-l of the two 

 daughter bodies than in E. worresteri between cirri F and /'. 



