Cytogamy
It has been reported in P. caudatum. It is an intermdiate process between conjugation and autogamy. In this process, two individuals come together for some time. Their nuclei undergo changes as occurring during conjugation, i.e. unicronucleus divides twice to form four daughter nuclei, the first division being meiotic one. Out of the four nuclei, three degenerate and the remaining one of each conjugant divides to form two nuclei. Both the nuclei fuse together in the protoplasmic cone to form a synkaryon. Thus, in this process, nuclear exchange like that of conjugation does not take place. The individuals than separate and divide.
Autogamy
Autogamy is a type of reorganisation found in P. aurelia. It is a sort of conjugation process in which only one organism takes part. During this process, the two micronuclei of the same individual fuse together forming a synkaron. During the process, macronucleus degenerate. Both the micronuclei divide thrice into a number of daughter nuclei. The first division is being the meiotic one. Thereafter, all the nuclei degenerate except two which fuse together to form s synkayon in a protoplasmic cone. The synkaryon divide to produce four daughter nuclei; out of the four two differentiate as macro and two as micronuclei. The cell body divides by a transverse construction and the micronuclei divide simultaneously two daughter paramecia.
Encystment
This phenomenon has been reported only in P. bursaria. During unfavoutable condition the body of paramecium become oval and it secretes a thick cyst round itself to yide over the unfavourable condition. The cyst appear like sand grains.
Nuclear reorganisation
Degeneration of old macronucleus and formation of a new one by the fusion of micronuclei is called nuclear organisation. During binary fission, the macronucleus divides by anitosis in which chromosomes are distributed at random in the daughter macronuclei. The genic balance of macronucleus is disturbed due to repreated binary fission. This results in less vigour and vitality of the daughter individuals. After passing through a certain number of asexual generations, the daughter paramecia die for want of nuclear reorganisation. Replacement of such a macronucleus becomes necessary to rejuvenate the aging paramecia. This old and decaying macronucleus is replaced by a new one during conjugation, endomixis.
It has been reported in P. caudatum. It is an intermdiate process between conjugation and autogamy. In this process, two individuals come together for some time. Their nuclei undergo changes as occurring during conjugation, i.e. unicronucleus divides twice to form four daughter nuclei, the first division being meiotic one. Out of the four nuclei, three degenerate and the remaining one of each conjugant divides to form two nuclei. Both the nuclei fuse together in the protoplasmic cone to form a synkaryon. Thus, in this process, nuclear exchange like that of conjugation does not take place. The individuals than separate and divide.Autogamy
Autogamy is a type of reorganisation found in P. aurelia. It is a sort of conjugation process in which only one organism takes part. During this process, the two micronuclei of the same individual fuse together forming a synkaron. During the process, macronucleus degenerate. Both the micronuclei divide thrice into a number of daughter nuclei. The first division is being the meiotic one. Thereafter, all the nuclei degenerate except two which fuse together to form s synkayon in a protoplasmic cone. The synkaryon divide to produce four daughter nuclei; out of the four two differentiate as macro and two as micronuclei. The cell body divides by a transverse construction and the micronuclei divide simultaneously two daughter paramecia.Encystment
This phenomenon has been reported only in P. bursaria. During unfavoutable condition the body of paramecium become oval and it secretes a thick cyst round itself to yide over the unfavourable condition. The cyst appear like sand grains.
Degeneration of old macronucleus and formation of a new one by the fusion of micronuclei is called nuclear organisation. During binary fission, the macronucleus divides by anitosis in which chromosomes are distributed at random in the daughter macronuclei. The genic balance of macronucleus is disturbed due to repreated binary fission. This results in less vigour and vitality of the daughter individuals. After passing through a certain number of asexual generations, the daughter paramecia die for want of nuclear reorganisation. Replacement of such a macronucleus becomes necessary to rejuvenate the aging paramecia. This old and decaying macronucleus is replaced by a new one during conjugation, endomixis.
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