256 GENERAL HISTORY OF THE INFUSORIA. 



possibly an instance of such a process, entirely fails, in om^ opinion, to sus- 

 tain the supposition. The occurrence alluded to was that of a thin, pellicular, 

 irregularly-shaped sac — sometimes of two or three such, — which elevated itself 

 above the surface of the ActinojDlirys, and presently burst, emitting some 

 fluid and fine granular matter, and then contracted. " Does this emitted 

 fluid," he asks, " contain the germ of future generations?" We think not ; 

 for, to our mind, the phenomenon mtnessed was nothing more than the 

 bursting of superficial vacuola, j^robably acting as excrementory media ; and 

 if this view be not correct, Mr. Weston's is improbable, inasmuch as such a 

 discharge of germs from superficial sacs is without parallel in the history of 

 Protozoa. 



Conjugation. — The remarkable act of conjugation, also known as Zygosis, 

 has attracted very much attention in the class of animalcules under consi- 

 deration, among which it is of very frequent occurrence. Much discussion 

 has taken place concerning the purpose of this process. Most of its early 

 observers considered it a reproductive act, a sort of copulation between two 

 individuals ; but the tendency of opinion at the present day is to deny it this 

 natui^e, and to treat it as little more than an accidental phenomenon, without 

 apparent object or aim. Nevertheless its occurrence is so fi-equent, and the 

 process of so complete a character, that it is hard to believe it to be in vain 

 and to no purpose in the economy of the Actitiojpliryina. A difi'erence of 

 opinion likewise prevails as to the nature of the process, one set of authors 

 maintaining that there is an actual fusion and intermingling of substance 

 between the conjugating animals, whilst another party asserts that there is 

 no fusion, but merely a temporary adhesion or accretion between their bodies. 

 The determination of this question is very necessary before we can speculate 

 fairly respecting the pui'pose of the act. Kolliker, who was among the first 

 to carefully explore this phenomenon, described it as a process of complete 

 fusion, and surmised it to be of a reproductive character. Stein speaks at 

 one place of conjugation {op. cit. p. 148) in Act'moplirys and Fodophrya as 

 consisting in a fusion ( Verschmehung) of the animalcule. At another (p. 160) 

 he describes it as an organic union of two or more individuals into a group, 

 involving no fusion of their contents, but only a cohesion by their suii'aces ; 

 and goes on to say (p. 161) that the coming together of two Actinoplirides is 

 due to external forces, and that the first thing observed is an entangHng 

 together of their tentacles, which act precisely in the same manner as when 

 a foreign body is seized upon, and by their contraction bring the bodies into 

 apposition. At the same time they fuse together and form a sort of commis- 

 sure, which is sometimes areolated, owing to interruptions to its continuity 

 by the incomplete confluence of the tentacles. In the case of Act. oculata, 

 several — as many as seven — individuals were seen by Stein connected toge- 

 ther, in a line, by this intermediate commissural matter, which he calls a 

 common mantle, — but all of them preserving their individuality, just as in the 

 instance of other species. This mode of connexion, by means of an interposed 

 matter derived fi'om the tentacula of the conjoined siu-faces, explains what Stein 

 means by conjugation being a fasion of the animalcules concerned — not a 

 fusion or commingling of their substance in general, as some have thought it. 

 Cohn, in his account of the conjugation of Actinoplwys {Zeitschr. Band iii. 

 p. QQ), noticed the connecting band or commissure to sometimes contain, 

 besides granules, particles of food, and vacuola, a vesicular body which he 

 presumed to be nuclear, or a germ, developed as a consequence of the zygosis 

 in operation. Stein encountered once or oftener a similar body, but concluded 

 that it was accidental, probably of vegetable origin, and not in any degree 

 embryonic; and (p. 164) he expresses himself satisfied that this act of con- 



