1921] NATURAL SCIENCES OF PHILADEPHIA. 157 



foresee that the next division would be longitudinal also, this on 

 account of the nucleus, which begins lengthening at right angles 

 to the longitudinal axis of each of the new individuals, even before 

 the separation of the couole is effected (Plate VIII, fig. 60), and 

 which then will be divided along a line parallel to the line of the 

 next division. 



In these young Flagellates, just beginning to divide, the anterior 

 part of the body broadens, and at the same time hollows into a 

 slight concavity, so as to take the form of a heart; the fissure gets 

 deeper and deeper (Plate VIII, fig. 60), and in proportion as it 

 lengthens downward, the lobes of the heart-shaped body become 

 more and more separated, moving in a respectively right and left 

 direction, with the result that at the moment the fissure reaches 

 the end of the body, the lobes, or new individuals, have each of 

 them turned 90 degrees, and lie with their posterior ends united 

 only b}^ a narrow bridge, the ultimate phase of the division, cutting 

 right through the bridge, will then appear to be transverse, while 

 in reality the division has been longitudinal. But this very narrow 

 bridge, which at last consists only of the very tough periplast sub- 

 stance, is not easy to break, the animalcule, or rather now both, 

 animalcules, struggle right or left, stretch and retract alternately, 

 and above all, twist and turn on their longitudinal axis as they 

 lie tail to tail; one of them, sometimes, is seen to twist to the left 

 while the other twists to the right (in fact each twists toward its 

 own right side), and at last the separating bridge, very thin and 

 contorted to the utmost, breaks and liberates the two young Flagel- 

 lates. The little Astasia is now free, and creeps or swims about 

 with an activity more remarkable than that observed in the adult 

 condition, no difference, however, is to be seen between those very 

 young individuals and the old ones, except, as already said, in the 

 normal possession of a flagellum. 



Speaking of his Euglena quartana, a colorless species also, Moroff 

 (25, p. 102) writes as follows: "I succeeded in obtaining individuals 

 which showed with some distinctness a stigma. At the beginning 

 none of the animals showed any trace of such an organ; but after 

 a few weeks I was able to obtain some, in which the eye was apparent 

 as a very small yellow spot, later on it had acquired an orange hue 

 and looked larger, but later still the eye remained in the same con- 

 dition, without my obtaining any further results." 



Astasia mobilis never shows any stigma, yet I found once, not 

 in a Cyclops but in a watch-glass where some Cyclops had been 



