44 The Ohio Naturalist. [Vol. VII, No. 3, 



dum.* Farmer and Moore f also consider that in the second 

 karyokinesis we have a continuation of the longitudinal splitting 

 begun during the first. We have thus a rational explanation of 

 the observed facts — an explanation as to why when pseudo- 

 reduction and qualitative reduction take place these processes 

 are so generally followed by a second karyokinesis. 



Accepting McClung's term, synizesis, for the massing or 

 contraction of the chromatin in the prophase of division, the 

 question remains to be settled as to whether this is a normal or an 

 artificial production. Two methods seem available for the solu- 

 tion of this problem. One may study the effects of plasmolizing 

 reagents on known structures and make comparisons or else one 

 may attempt to study the stages in question from the living 

 material. 



In 1S99J I found that a violent distortion of the chromatin 



and the so-called sickle stage of the nucleolus may be produced 



even in resting cells of the root tips of onions by using a violent 



killing fluid. This fluid was made according to the following 



formula: 



Absolute Alcohol 95 cc. 



Chloroform 5 cc. 



Glacial Acetic Acid 1 cc. 



Chromic Acid (8% H^O Solution) 1 cc. 



The combination proved to have a very bad effect as a kill- 

 ing reagent and was simply one of many tried in a series of exper- 

 iments. Figures 5 and 6 represent cell rows from opposite sides 

 of a section of onion root tip (Allium cepd) killed in this 

 fluid. Nearly all of the nuclei of the peripheral cells showed 

 decided distortions. The nuclei are crowded toward the outer 

 walls of the cells, while the nucleoli are generally pushed in the 

 opposite direction. The chromatin and other dark-staining 

 material is also massed to some extent on the inner side of the 

 nucleus. In the central strands there is little displacement al- 

 through the cells are shrunken. No such distortions are ever to 

 be seen in properly killed root tips and especially is there no such 

 svmmetrical arrangement of the nuclei and nucleoli in the outer 

 layers of cells. This appearance then is purely on artifact which 

 may be of assistance in the interpretation of other cases. In 

 judging of synizetic contractions, it is also important to take 

 into account the probable expansion of the nuclear cavity. The 



* . A Contribution to the Life-historv and Cyto- 

 logy of Erythronium. Bot. Gaz. 31 : 309-387, 1901. 



t Farmer, J. B., and Moore, J. E. S. On the Maiotic Phase (Re- 

 duction Divisions) in Animals and Plants. Ouar. Jour. Mic. Sci. 48 : 489- 

 551, 1905. 



IScHAFFNER, JoHN H. Artificial Production of the Sickle Stage of 

 the Nucleolus. Jour. App. Micr. 2 : 321-322. 



