71 



Nachdruck verboten. 



On the essential Similarities existing between the heterotype 

 nuclear Divisions in Animals and Plants. 



By J. Beetlakd Farmer, M. A., and J. E. S. Mooee, A. R, C. S. 

 With 29 Figures. 



In the various accounts which have been given of the process of 

 karyokiuesis, as it occurs in the heterotype divisions of the nucleus in 

 the reproductive elements, one meets with little or no recognition of the 

 fact that in one and the same species there may exist a considerable 

 range of variation, both in the actual form, and also in the mode of 

 development of the individual chromosomes. And yet this is a matter 

 which possesses some interest since it aifords evidence of variations 

 occurring at a specially important period in the life history of the 

 organism, and also it may possibly serve to throw some further light 

 on the essential stages in the metamorphoses through which the 

 chromosomes individually pass. 



We wish to describe in the present communication, some of the 

 chief and most frequently recurring types of such variations as we 

 have met with, since we think that in this way the fundamental simi- 

 larities which exist between animals and plants, as regards even the 

 minute details of the process, will be the more clearly brought out. 



Our observations in this place will be for the most part restricted 

 to the results we have obtained from a study of the spermatogenesis 

 in Triton, and the pollen-mother-cells of Lilies, though we shall also 

 have occasion to refer sometimes to other forms. 



In dealing with the Lilies, it will be necessary to give an account 

 of the normal metamorphoses through which a chromosome passes, 

 since the details of the process both in these and other plants seem 

 to have been misunderstood by previous writers. In the first place, 

 as regards Lilies, our statements must be taken as referring only to 

 the first (heterotype) division of the pollen-mother-cell. The second 

 mitosis is strikingly different and approximates to the homotype form 

 met with in the vegetative cells of the organism '). Similar difl'e- 



1) J. B. Farmer, Ueber Kernteilung in Liliumantheren etc., Flora, 

 1895, I. — See also Steasburgee's very accurate figures in his book on 

 Zellbild. u. Zellteil., PI. IX, Figs. 84, 85, 94, 95. 



