528 DESCRIPTION OP [Polygastrica . 



the parent; the bud is first egg-shaped, ovate, (P. 22, f. 1) ; but 

 even when completed, does not attain the size of its parent. More 

 than one bud may be in process of development, fi'om the same indi- 

 vidual, at the same time. In their course of growth, buds resemble 

 the beings resulting from fission, both in the formation of the frontal 

 wreath, and in the production and subsequent disappearance of a 

 posterior ciliated zone. 



These two modes of propagation are not peculiar to the most 

 complete and largest animals, but appertain also to the smaller forms : 

 this fact, together with the minute size and rudimentary character 

 of vorticella-like forms in the vicinity of larger ones, led Dr. Stein to 

 believe the existence of a third method of reproduction. He met 

 with examples of V. microstoma from l-76th. to l-126th. of a line, 

 and others from l-190th. to l-380th. ; but in such there was no con-' 

 tractile stem, and they possessed but the general outline of form of 

 Vorticella ; yet between these extremes in magnitude there was 

 every intermediate size (P. 22, f. 6, a. b. c. d. e.) 



In the smallest specimens no anterior cilia could be detected, 

 (P. 22, f. 6, d. e.); yet they could detach themselves from the 

 granular mass to which they adhered, and swim fi-eely about, ex- 

 tending and contracting themselves Kke larger forms. 



Together with the various sizes of Vorticella microstoma, and amid 

 the granular nidus in which they existed, Dr. Stein further found 

 numerous nucleated cysts, l-50th line in diameter, and about half 

 the length of full gro^^^l I'orticeUce. 



These cysts had a clear, double outline, and contained a homo- 

 genous, transparent, colourless substance, having mostly numerous 

 granules. (P. 22, f. 5, 6.) These were in fact contracted Vorticellce, 

 each cyst containing a single being. In most, the characteristic 

 band-like nucleus could be detected ; in many, also, the involuted 

 frontal wreath, with the oral cavity and gullet, looking like a fissure 

 in the anterior part of the cyst ; and, moreover, the contractile sac, 

 yet active (P. 22, f. 5 and 7) ; on the other hand, he never ob- 

 served the globules of food seen in the uncontracted (un-encysted) 

 animalcules. 



In other cysts, again, the frontal portion and alimentary tube could 

 not be traced ; but they possessed the contractile vesicle, — sometimes 



