92 T. C. HMilgard—Infusorial Circuit of Generations. 
thin but chemically homogeneous organic substances being im- 
permeable to certain gases, while permeable to others, a good | 
deal of physiological interest is involved in the study of this 
protoplasm-membrane, and its relation to the swamp-gases. 
The particles of the nubecula are uniformly globular. 4 
_ After repeated cross-segmentations, these undulate fimbriate — 
bodies, always revolving about the long axis (while evidently 
traveling onward by the action of the ciliate mouth) divide 
lengthwise, from below upward; thereby becoming somewhat 
urse or tear-shaped; the mouth being split in two, so that 
th stand “plying” mouth-to-mouth, while yet connected at 
. as it were. ese finally tear asunder by 
indentures, after which each has the shape of a crooked glass- 
te en more adult, and about ;'; of a line long, the im- 
ternal yolks and designs have disappeared ; the sarcode assumes 
a uniform yellowish tinge; its mouth forms deep cavities, while 
its front is toppling over like the hood of an Indian turnip — 
(Arum triphyllum) or of a Sarracenia leaf. It now contracts — 
to a globe and encysts. When a smooth, transparent crust 1s 
formed, gradually an inward gyration of cilia (as of an enclosed 
centipede) which ultimately becomes very violent, is observ- 
able; and at last the excessive fatigue of watching this tanta- 
izing gyration may be rewarded by seeing the inmate emerge, — 
either as quite a large but excessively limber, fluttering and 
transparent, full-size, single Oxytricha; or else several smaller, 
mostly narrow, triangular slips)* escape, with the same exceed- | 
ingly restless volubility ; the marginal bristles not yet bemg | 
stiffly extended in a plane, but ruffled up and down like the | 
bristles on the undulating borders of a thistle-leaf. As they — 
feed and the tissues become scatent, the entire form of an 
Oxytricha is presently acquired. 7 
I have observed still another development of Oxytricha; 18 
first source, however, being as yet unknown to me. ere 
appear on the field of action numbers of quaint-looking, big- 
eyed balls, about ;3; line thick, snouted, as it were, with @ 
rt of “hair-lip” resembling a duck’s bill; the stiff bristles 
within the bill-shaped mouth quivering with a sort of expres 
sive smirk, and looking aopdtand odd. : 
hey come full-sized and booming upon the stage, and m 
-* The figures L and M, p. 447, in Carp. “ Micr.” seem to belong here. 
