and Laboratory Methods. 1761 



Nathaasohn, Alexander. Physiologische Unter- This paper gives the results of an in- 

 suchungen iiber amitotische Kerntheilung. vestigation made by the writer under 

 Jahrb. f.wiss. Bot. 35: 48-So, pis. 2-3, igoo. ^^ r ^r m , • ■, ^ . . 



Prof. Pfeffer s guidance at Leipsic. 



The investigator worked almost exclusively with living material and depended 

 chiefly upon Spirogyra orbicularis grown either under natural conditions or in 

 culture dishes in the laboratory. The best results were obtained by exposing 

 plants to a temperature of -f- 2°C. during the night and thus stopping cell divis- 

 ion ; the following morning growth was renewed in the warm laboratory. As 

 soon as the first division was completed, the plants were placed in a one per 

 cent, aqueous solution of ether, and in this continued to divide. In cells which 

 had begun to divide indirectly, the process was completed, but amitosis followed. 

 In order to study the behavior of the nuclei in detail, the observer fixed fila- 

 ments in Flemming's solution, stained them for forty-eight hours either with 

 dilute safranin or with Grenacher's borax-carmine, and mounted them in Vene- 

 tian turpentine. 



When plants which had been dividing amitotically in ether-culture were 

 placed again under the influence of normal conditions, cells formed through 

 amitosis divided karyokinetically and even conjugated, producing zygotes in the 

 typical manner. 



A large species of Closteriuni was grown upon agar-agar and studied both in 

 water and in the ether solution, but the plants seldom showed amitosis. In so 

 far as similar observations upon higher plants were concerned, the results were 

 generally negative. Stamen hairs of Iradescantia virginica sometimes exhibited 

 amitotic division of the nucleus. In the injured root tips of Vicia Faba, Phase- 

 olus multiflorus , Lupinus albus, Phalaris canadejisiis and Marsilea quadrifolia 

 only karyokinetic divisions were observed both in repair tissues and the vegeta- 

 tive point. On the contrary, in cut twigs of Sambucus ?iigra and in the injured 

 cotyledons of Phaseolns multiflorus amitosis occurred. From the study of Popu- 

 lus nigra, it was judged that cells poor in cytoplasm tended to divide directly. 



The author states in conclusion that the occurrence of mitosis or of amitosis 

 does not necessarily depend upon internal peculiarities of the nuclei, but varia- 

 tion in this respect may be induced by changes in external conditions. He 

 believes that cells formed through amitosis may give rise to daughter cells which 

 possess all the embryonal qualities and undiminished power of development. 

 Therefore he says that mitosis and amitosis may be physiologically equivalent, 

 that karyokinesis is not necessary to a distribution of those elements which bear 

 the hereditary qualities, and that the nucleus cannot be considered the sole pos- 

 sessor of those elements. Carrie M. Derick. 

 McGill University. 



