THE MEROTOMY OF CILIATED INFUSORIANS. 205 



to forty-eight hours at most ; the cause of death is the alteration 

 of the plasm, which presents a vacuolated or spongy aspect owing 

 to aqueous imbibition, and probably also to the arrest of the 

 functions of assimilation. The principal seat of aqueous imbibi- 

 tion is probably the wound, owing to its not being completely 

 closed. The same cause which prevents the reproduction of the 

 lost parts prevents also the disappearance of the irregularities of 

 form which are often the consequence of traumatism and which 

 give rise to the merozoite. These irregularities fully disappear in 

 the course of regeneration among the nucleated merozoites. 



(7) The opinion of Gruber that the nucleus is necessary to 

 give an impulse to the formation of new organs and useless for the 

 further development of these organs is inexact. The presence of 

 the nucleus is indispensable at all stages in the formation of the 

 organs. 



(8) When a merozoite without a nucleus has been taken from 

 an individual which is preparing for spontaneous division, but has 

 not yet shown any sign of outward contraction, the division of the 

 merozoite takes place as if it continued to form part of the intact 

 individual ; but, whilst this would have given birth to two com- 

 plete buds, the merozoite produces only portions of the two buds 

 which would have formed at the expense of the mass of plasm 

 which composed it. 



The division is but rarely carried to a complete separation of 

 the two parts. As soon as it arrives at a certain stage, a retrograde 

 movement takes place, and the two parts are again mingled in a 

 common mass, which is destroyed by degeneration. When one of 

 the two parts is only a miniature of the other, it sometimes be- 

 comes completely independent, but soon perishes. It is to be 

 inferred from this observation that the impulse which determines 

 the division of the plasm comes from the plasm itself and not from 

 the nucleus, but that the nucleus is necessary to sustain this 

 impulsion and carry the division to the end. 



(9) The micro-nucleus, whether alone or accompanied by the 

 nucleus, takes no part in the regeneration or other vital manifesta- 

 tion of the plasm. Its object is to intervene in the phenomenon 

 of conjugation ; it is, to use Biitschli's expression, a sexual nucleus 

 (Geschlechtsken). 



