18 GENERAL HISTORY OF THE INFUSORIA. 



foreign bodies. Very probably the contents, in the above-described cases, 

 were ali'eady abnormally altered, and incapable of further development. 



*' In other conjugation- cells the young spore displayed a still thicker mem- 

 brane, covered on the outside with tiimcate- conical elevations, in which 

 membrane could be detected a composition of two colourless layers. The 

 outer of these layers remained clear and transparent even in the advance to 

 maturity. Its elevations became developed into rather long spines, which 

 forked at the apices into two or four branches. The deeper- seated layer of 

 the spore-membrane meanwhile assumed a dark-brown colour. By rolling 

 under the covering-glass, the tough, colomiess, outer layer may be readily 

 stripped from the inner, more brittle, brown layer ; then the latter appears 

 covered on its outer surface with slight elevations, similar to those which 

 first appeared upon the yoimg spore. The brown layer of the spore-coat 

 encloses a thii'd, delicate, coloiuiess layer (perhaps the primary membrane 

 of the spore) which immediately envelopes the cell-contents. 



*' At the beginning of July, the green contents of all the spores appeared 

 conglobated into a spherical mass with sharp outlines, which, lying free in 

 the middle part of the cell, nowhere touched its internal Avail. Three weeks 

 later, in many of the spores these contents appeared separated into two 

 flattened ellipsoidal masses; when I cracked the cell by careful pressui^e, 

 I was sometimes successful in diiving out one or both of the masses of 

 contents in an uninjured condition. They could then be recognized beyond 

 aU doubt as primordial cells; bodies destitute of a solid ceU-membrane, 

 having a thin coat of protoplasm which * bubbled ' out in water, to which 

 adhered a thick investment, coloiu-ed bright green by numerous imbedded 

 chlorophyll-granules, sm-rounding a central ca^-ity filled with transparent 

 fluid. The fluid contained in the spore in which the two primordial cells 

 were immersed, was not colouiless, but rendered tui'bid by numerous im- 

 measui-ably smaU granules exhibiting molecular motion. In August each of 

 the ellipsoidal primordial cells had divided into two globular cells, of similar 

 character to the mother-cell. Towards the end of September, some of the 

 spores exhibited another such division, so that they then contaiaed eight, not 

 globular, but strongly flattened primordial cells. Most, however, passed 

 through the winter-rest imchanged, during which the majority died. At 

 the beginning of April of the next year, the spinous, transparent, outermost 

 layer of the coat was more or less completely decayed on all the spores, even 

 on those which were still to be recognized as living by the vivid green colour 

 of the contents. AU the spores still alive contained at least eight, many six- 

 teen daughter-cells, all very strongly flattened, almost discoid. In several 

 spores the outline of the daughter-cells was no longer cu^ular, but displayed 

 two shallow lateral notches. The still -existing, brownish, inner layer of the 

 spore-coat was now seen to be softened ; it no longer exhibited its former 

 brittleness, and it was difficiilt to crack it by pressure. Daughter-cells whose 

 lateral constrictions were most strongly marked, were about half as large 

 again as the circular, whose diameter about equalled that of the isthmus of 

 the former, and they almost entirely filled up the cavity of the spore. When 

 these were pressed out from the crushed spore, their form and size agreed 

 almost exactly with that of Cosmarium Meneghinii. 



" I saw similar phenomena in the spores of Cosmarmm undulatum (Corda), 

 in which the investigation is rendered very difficult by the minute size, and 

 which, cultivated for some months in my room, entered abundantly into con- 

 jugation. In this, again, I observed the contraction of the green contents of 

 the cell into a globule occupjdng the central part ; the division of this ball 

 into two, foiu', eight, and sixteen spherical masses ; finally, the transition of 



