JENNINGS: DEVELOPMENT OF ASPLANCHNA HERRICKII. 89 
a testis. Again, in his Rotatoria (Wrotki) Galicyi, Wierzejski (92°) 
gives a figure of the entire animal, with special figures of the character- 
istic glandular organ, the trocbal field, the jaws, and the excretory 
system, together with a briof description in the Polish language. 
Asplanchna Herrickii was afterward reported by the author (Jennings, 
'04) as occurring in Lake St. Clair, and by Levander (795) as occurring 
in the neighborhood of IIelsingfors. 
2. Development. 
The unsegmented egg of Asplanchna Herrickii is similar in form to 
that of Callidina russeola, investigated by Zelinka, but slightly smaller, 
the maximum dimensions in Callidina being 130 by 90 a, while the maxi- 
mum dimensions observed in Asplanchna Herrickii were 97 u by 83. 
No thick-shell * winter eggs" were ever observed by me in tbe 
speeimens taken; possibly later in the fall these would have been 
found. 
In regard to the details of the developmental process, reference must 
be made to Part First; the purpose here is merely to point out such 
observations as are of importance from the standpoint of rotifer 
morphology, noting especially any differences between my account and 
those of other writers. 
A. MATURATION. 
As stated on page 13, the place of polar-cell formation in Asplanchna 
has a different relation to the axes of the egg from ‘that ascribed to it by 
Zelinka in Callidina. In the ensuing discussion I shall, for convenience 
of comparison, use the orientation adopted by Zelinka ; that is, what I 
have called the “macromere end” is anterior, the “micromere end” 
posterior. That side of the egg upon which later the blastopore is 
found, occupied in early stages chiefly by the quadrant D, is ventral, the 
opposite side dorsal. These terms have no constant relation to the 
terms of orientation employed in Part First. 
As previously deseribed and figured (Plate 1, Figs. 1 and 2), the polar 
cell is formed near one of the ends of the ellipsoidal egg, and the place of 
formation is cut by the first and second cleavage furrows (Figs. 6 and 8). 
The same is true for Asplanchna priodonta, 
In these two species of Asplanchna, therefore, the place of polar-cell 
formation is the same, with reference to the form of the egg, as that 
described by Lameere (90) for Asplanchna Sieboldii, and by Zelinka 
(91) for Callidina Leitgebii (p. 53) and Melicerta ringeus (p. 117). Iu 
