1881.1 



MICEOSCOPICAL JOLTKKAL. 



189 



the protruding parts were after a 

 considerable time (from a quarter to 

 half an hour) retracted again. I was 

 disposed to attribute this to lack of 

 aeration in the grooving slide, as I 

 saw, under similar circumstances, fis- 

 sion begun in Trachelocerca, and not 

 carried to completion, the animalcule 

 resuming its original form as if not 

 having vigor for the attempted pro- 

 cess. 



In another case of an Actinophrys, 

 which had been traced into the opa- 

 line condition, the plasticity went so 

 far that a churning movement was 

 seen within it, almost as marked as the 

 periodic movement seen within roti- 

 fers. In one instance the whole body 

 had the appearance of a sac to which 

 the churning motion gave change of 

 shape, making it partly roll over on 

 the bottom of the slide. In this case 

 upon purposely agitating the water by 

 pressing the cover-glass with a 

 needle, the animalcule gradually re- 

 sumed its regular rotundity, and after 

 a time showed faint and thin rays 

 again. 



In some instances when the ani- 

 malcule was watched through the 

 changes leading into the rayless, opa- 

 line condition, it finally collapsed, its 

 contents making only a mass of fine 

 granular matter, in which I saw no 

 subsequent motion or life, but only 

 the ordinary appearance of decay and 

 death. In others, however, the evi- 

 dence of separation into a brood of 

 young was as strong as in case 2, de- 

 tailed above. 



In several examples, soon after con- 

 jugation and subsequent separation 

 had taken place, say within fifteen or 

 twenty minutes, a single small rayed 

 specimen, of the size and appearance 

 of those already described, was found 

 in close proximity to the mature in- 

 dividual under observation. It hap- 

 pened that these appeared on the 

 under or upper side of the animal- 

 cule, so that the process of gemmation, 

 if such it was, was not seen in the 

 cases in which conjugation had been 

 watched. In one case, when a single 



Actinophrys was under the glass, no 

 knowledge being had of its preced- 

 nig history, there was the apparent 

 excretion of a small mass which moved 

 quickly out to the end of the rays 

 and floated off. Its regular appear- 

 ance attracted attention, and, keeping 

 it under observation for half an hour, 

 it had distinctly put forth rays and 

 precisely resembled the young so often 

 referred to. 



This record of observations is offer- 

 ed as a contribution to the life-history 

 of the Actinophrys, without insisting 

 too strenuously upon the conclusions 

 to which they point. I have given 

 the points in which the continuity of 

 observation was broken, so that no 

 more close connection of sequences 

 in the phenomena may seem to be as- 

 serted than actually occurred, and 

 that appearances needing verification 

 may attract the attention of other 

 observers. They point distinctly to 

 two modes of reproduction ; one, by 

 single gemmation after conjugation, 

 the other by segmentation of the par- 

 ent into a brood of young after pass- 

 ing through the opaline condition de- 

 scribed. 



I purposely neglected examples 

 which seemed to become encysted as 

 my method of manipulation did not 

 afford the means of long-continued 

 preservation of the specimens. The 

 apparatus I found most convenient 

 was a plain slide and cover-glass, 

 which, .when not under observation, 

 was laid across the top of a small 

 dish of water, a narrow shred from 

 an old handkerchief connecting the 

 edge of the cover-glass with the water 

 below, and supplying the moisture by 

 capillary attraction. The only limit to 

 the preservation of the slide in the 

 growing condition was the deposit of 

 salts from the water by evaporation, 

 which after a time became sufficient at 

 the edge of the cover-glass to interfere 

 with aeration. A single slide was, 

 however, kept under observation for 

 periods varying from a week to a 

 fortnight. 



