48 J. T. CUNNINGHAM. 



2)olij2)o(l{a \n the process of tlivisioii, and tlie changes which, 

 according to his description, took place in the nucleus, were 

 very different to those of karyokinesis. The nucleus, which 

 was large, single, and well defined, first became dumb-hell- 

 shaped, and then divided by an increased tension of the 

 central part. Other infusoria, which have been observed, 

 conform in dividing more or less closely to the karyokinetic 

 laws. The dividing nucleus of the flagellate Anisonema 

 sulcatum, figured by Blltschli,^ is not unlike an achromatic 

 spindle with a chromatic figure at each end. The large 

 nucleus of the peritrichous species Spirocliona gemmipara, 

 according to R. Hertwig," is longitudinally striated during 

 division, though it differs widely from a typical nuclear 

 spindle. The shape of the nucleus of the acinetan Fodophnja 

 quadripa7'tita,^g\ived by Biitschli,^ is unlike anything found 

 in karyokinesis ; but here also the cellular bud encloses a 

 segment of the nucleus. 



Dr. Gruber, in his recent memoirs on the process of 

 division in monothalamous Rhizopoda (' Zeitschr. wiss. 

 Zool.,' Bds. 35 and 36), has discussed the relation of the 

 peculiar phenomena discovered by him to indirect cell- 

 division. He shows how the rapid formation of a new 

 animal at the mouth of the mother, out of protoplasm and 

 shell-plates accumulated for the purpose beforehand, is 

 easily derived from a division like that of Atfioeba. The 

 presence of a firm shell prevents the actual division of the 

 animal, while by the previous formation of shell-plates in the 

 maternal protoplasm the new individual is provided with a 

 protective covering at the commencement of its separate 

 existence. The division of the nucleus does not take place 

 till the new animal is already complete, and this Dr. Gruber 

 considers supports Strasburger's view that the division of 

 the cell is independent of that of the nucleus ; and it also 

 shows that the whole process proceeds from the activity of 

 the cell-protoplasm, the nucleus playing a subordinate part. 

 In Euglypha alveolata the nucleus, before dividing, either 

 became granular or " gewundene Linien " appeared in it, 

 then it elongated and showed longitudinal lines. Dr. 

 Gruber thinks that these changes represent Flemming's 

 convolution and equatorial plate. If so, the resemblance 

 between the indirect division in Rhizopods and the cells of 

 Salamandra is not very close. 



Free Formation of Nuclei. — A.nother question which pre- 



» 'Zeitschr. Wiss. Zool./ Bd. 30, fig. ISe. 

 - 'Jenaische Zeitschr./ vol. xi. 

 3 lb., vol. X. 



