44 J. T. CUNNINGHAM. 



collections of regular loops with their free ends turned 

 towards the plane ; and there was no fusion of the loops 

 after their removal to the poles ; they formed the wreath and 

 convolution as in typical cases. 



In the formation of endosperm in the embryo sac of 

 Phanerogamia, the division of the nucleus is not immediately 

 followed by that of the cell^ but after the full number of 

 potential cells has been formed, cell walls arise in a peculiar 

 way. Each pair of nuclei is connected by the strise of the 

 achromatic spindle, and at the equator of this there appears 

 a series of thickenings, which Strasburger believes, from 

 their behaviour to iodine, to consist of starch or sonie allied 

 substance ; out of these is formed the partition wall of 

 cellulose between the newly formed cells. Strasburger 

 names this series of thickenings the " cell plate," a term 

 which Klein has used to denote the body of the cell as 

 distinguished from its nucleus. In the dividing testicular 

 cells of Salamandra, in which the achromatic spindle is 

 very conspicuous; Flemming has seen equatorial thicken- 

 ings corresponding to the cell plate of plants ; but as 

 neither these nor the spindle were to be seen in the living 

 cells, he was unable to determine their function. He also 

 found a corresponding structure at the equator of the 

 achromatic spindle of the first dividing nucleus in Echino- 

 derm ova (^ Beitrage,' iii Theil) ; this was figured by Fol ^ 

 under the name " filaments connectifs."" The appearance 

 seemed to Flemming to be caused by a bending and winding 

 of each fibril of the spindle for a short distance, and not to 

 be due to swellings or thickenings. 



Development of Spermatozoa. — Flemming succeeded in fol- 

 lowing the nuclear changes in actual progress in living 

 cells from the testes of Salamandra ; the fibrils when first 

 observed were already in the form of numerous loops, 

 these passed towards the poles of the nuclear space and 

 back towards the equator in alternate systole and diastole 

 before the formation of the equatorial plate. The fol- 

 lowing stages took place in accordance with his general 

 description, except that no longitudinal splitting was ob- 

 served ; of this phenomenon he was unable to obtain evi- 

 dence in Triton, Batrachia, plants, and mammals. Pere- 

 meschko^ has observed the division of living cells i7i situ 

 in the larva of Triton cristatus. Epithelium cells, stellate 

 connective-tissue cells, white blood-corpuscles, and the 

 spindle-shaped cells of vasifactive tissue, showed the same 



I ' recoudatiou et commeucement de riieuogenie/ Geneva,' 1879. 

 ? ' Arcliiv Mik. Anat.,' Bd. 16. 



