CHAP. I 



The Cell i8r 



phosphorus was first discovered. He named its primary 

 constituent nuclein. Altmann showed in 1889 that nuclein 

 is a compound that can be decomposed into nucleinic 

 acid and a kind of albumin. Kossel in 1893 identified 

 such compounds of nucleinic acid and albumin with the 

 chromatin of the histologists. 



The centrosome was discovered to be an inseparable 

 companion of the nucleus in animal cells by Flemming 

 and by Van Beneden in 1875 and 1876. Its presence in 

 plants was not recognized till 1891 and 1892, when Guignard 

 claimed to have discovered it in the sporogeneous tissue 

 of Lilium Martagon. Farmer observed its occurrence in 

 certain liverworts in 1895, but he entirely failed to confirm 

 Guignard as to its presence in the flowering plants. A 

 somewhat heated controversy arose, in which Belajeff, 

 Osterhout, and Mottier took part. None of these observers 

 agreed with Guignard, so that the association of centro- 

 somes with nuclei in the higher plants remained entirely 

 hypothetical at the end of the century. 



The determination of the behaviour of the nucleus in 

 the process of cell-division was one of the most important 

 discoveries in cytology made prior to 1900. Before 1860, 

 Remak and others had shown that its own division was 

 an essential part of the process of the division of the cell, 

 but no detailed investigation of the changes was made till 

 1873, when it was observed by Schneider. From this time 

 the study of the phenomenon was undertaken by many 

 biologists, among whom were conspicuous Schleicher, who 

 gave it the name karyokinesis, Van Beneden, Flemming, 

 Schmitz, and Strasburger. Van Beneden distinguished 

 between fragmentation and division in 1876. The terms 

 indirect, and direct, nuclear division were introduced by 

 Flemming in 1879, an d were long in favour. In 1882 the 

 same writer suggested the terms mitosis and amitosis, which 

 also came into general use. 



