804 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
fibres. The local modifications of the wound, and the contractions of 
the body which aid in closing it should be considered as phenomena 
caused by the wound. The phenomena of excitation may be observed 
as well in the fragments or merozoites which contain a nucleus as in 
those that have none. After this period of excitation, which is generally 
of short duration, the fragments regain the regularity of their move- 
ments, and their normal orientation — behave, in a word, like ordinary 
Stentors. The most obvious and most remarkable phenomenon of 
merotomy is the rapid and complete regeneration of the merozoites which 
contain the whole or part of a nucleus. If the peristome be removed it 
is reformed by a rudiment which, as in reproduction by division, appears 
at first on that part of the ventral surface which was called by Schuberg 
the branching zone. The new peristome is then completed by a mouth 
and an adoral zone, which are also formed as in the process of division. 
The contractile vesicle is reproduced, not as a new organic formation of 
the protoplasm, but by a simple local dilatation of the previously exist- 
ing excretory system. The reconstitution of the nucleus is the last 
act in the regeneration of the merozoite ; it is effected by successive 
divisions of the nuclear joint or joints which the merozoite first con- 
tained. The nuclein increases in quantity at the expense of the proto- 
plasm. The regeneration of the merozoite is sometimes followed by a 
tendency to multiplication by division, but the new parts are soon reab- 
sorbed, and the individual regains its primitive appearance. This phe- 
nomenon is probably due to increased physiological activity of the 
nucleus caused by the lesion. 
The merozoites which do not contain any part of the nucleus are 
never converted into a complete individual ; if this portion contains the 
mouth or anus it ingests food or gets rid of undigested masses, just like 
normal individuals. This shows that the nucleus has no influence on 
the ingestion or removal of food. Merozoites without a nucleus do not 
survive for more than forty-eight hours at the most ; the cause of death 
is the alteration of the protoplasm, which becomes vacuolated or spongy 
in consequence of an inhibition of water and, perhaps, also from the arrest 
of the functions of assimilation. 
The opinion of Gruber that the nucleus is necessary to give an im- 
pulse to the new organs and useless for their further development is 
inexact ; the presence of a new nucleus is indispensable for all the stages 
jn the formation of the organs. The “ micronucleus,” whether alone or 
accompanied by the nucleus, takes no part in regeneration or the other 
vital manifestations of the protoplasm. Its office is to intervene in the 
phenomena of conjugation ; it is, to use the expression of Butschli, a 
sexual nucleus. The non-intervention of the micro-nucleus in the vital 
phenomena of protoplasm is again shown by the fact that it has no in- 
fluence on the intracellular absorption of the joints of the old nucleus, 
at the time of conjugation. It is only when it has by its fusion with a 
congeneric element of another individual become a true active nucleus 
that it has an effect on the absorption of the old nucleus. This absorp- 
tion, which has a close resemblance to the digestion and assimilation of 
food, is probably effected by a secretion which has its seat in the proto- 
plasm, and is, like other secretions of the Protozoa, dependent on the 
nucleus. 
