762 MICEOSCOPIC FOKMS OF ANIMAL LIFE 



saprophytic organism l of special character. have been discovered 

 during a recent period. But it will be of more moment here to note 

 to what an extent in this series of observations tin' in } n- homogeneous 

 objectives, especially in their apochromatic form, have been succes>- 

 fully employed in enlarging the area of knowledge. 



The present Editor has gone carefully over the greater part of the 

 work, revising all the critical points with the best apochromatic ob- 

 jectives, and the homogeneous forms of achromatics with an aperture 

 of 1'50 and with a clear demonstration of the immensely greater ease 

 with which the work could have been done had these lenses been used 

 in the original investigation. 



But the easily accessible proof of this is given in the work done by 

 I )r. I >allinger upon the ituclt-HN of the nucleated forms of these monads. 



Briefly to present the facts, we may recall the part taken in the 

 net of fission in the form last described (Ilnlli tnji'rin l)fi/sd<di). It 

 will be seen by reference that it appeared to us that the /x/cli'/'s fol- 



*/ l_ l 



lowed tin' i>roc(-srx inaugurated b;/ tin' xunintic sarcode. That in fact 

 it was a passive participator in the act of fission. This is all that 

 can be made out to-day by the very lenses originally employed. 



But by the employment of a /..th inch and ..^th inch homo- 

 geneous of X.A. I'HO by Powell and Lealand. and an apochromatic 

 of /oth inch N.A. 1'40 by the same firm ; and also by the use of 

 the beautiful 3 mm. and '1 mm. X.A. 1 "40 of Zeiss (apochromatic). 

 it can be seen with comparative ease ilmf it i* in tin 1 nn.cli'ns tlmt 

 nil the activities of the body arc (iriijinnt/'/l . 



This may be followed from a study of Plate XVI. Fig. 1, A. 

 represents the nucleus of the form drawn at fig. 1. E, Plate 

 XV. In long diameter it is of an average length of -rth f au 



inch ; hut instead of being a darkly refractive object, as seen with 

 the objectives used twelve years ago. it is with the present lenses. 

 freed from chromatic and spherical aberration, a body in the monad 

 undergoing no process of change, an oval globule with a complicated 

 plexus-like involution throughout its substance, as seen in fig. n. A. 

 I Mate XVI. But directly the process of fission is to be inaugurated. 

 we need not wait to see its first action in the splitting of the 

 tiagellum. as in fig. i>, E, Plate XV ; for by observing the nucleus 

 we discover,. before any change has begun in the body-substance. 

 that the plexus in the nucleus has condensed itself on cither sidi- "/ 

 ///* nucleus, as in fig. i ? o, A. Plate XVI. A clear space is left at c, 

 and no change has taken place in the body-sarcode, . a. a. But. 

 shortly an incision takes place in the nucleus, as at </. fig. 2. and 

 this is immediately fitllinn-if by the incision f in the body-sarcode, 

 and the process goes on simultaneously in nucleus and body, as in 

 tig. :'., until the division of the nucleus is completely effected, and the 

 total severance of the bodv follows. 



But as soon as the nucleus is ilir'ti'<l , the plexus, which has been 

 during division, as in fig. :;, condensed over /HI ft of each dividing 

 half, at once distributes it self evenly again, as in tig. (i. A. and re- 

 mains so until another change is inaugurated in the form to which 

 the nucleus belongs. 



1 -Inii ni. nf J{di/(il Micron. Soc. vol. v. 



