﻿BOTANICAL GAZETTE 



ternata 4 chromosomes were found. This would seem to be the 

 lowest number yet found in plants. The following quotation from 

 Digby's (3) investigation on Crepis wrens states: "Crepis virens, 

 as has been shown by Rosenberg, possesses only 6 somatic chromo- 

 somes, the lowest number hitherto recorded in plants." Six 

 chromosomes are also recorded by Wisselingh (12) in S. setiformis, 

 and by Karsten (5) in S. jugalis. The number of chromosomes 

 in S. bellis agrees with that found by the writer (8) in S. crassa, 

 namely, 14. Since a single genus of plants, as shown in Spirogyra, 

 exhibits such striking differences in the number of chromosomes, 

 there is no foundation for the assumption that nuclei in plants of 

 a similar genus will show similar morphological organization. 

 Morphological variation in the nucleus obtains in different species, 

 just as variations occur in the number and winding of chroma- 

 tophores and in cell dimensions. 



In the 3 varieties of 5. bellis also minor variations were seen in 

 karyokinesis. So far as known to the writer, such variations in 

 nuclear division have not been worked out in detail and established 

 for any particular plant. Mitzgevitsch (10), working on 5. 

 subaequa and 5. jugalis, found differences in the distribution and 

 origin of chromatic material in the prophase; but to establish 

 distinctions in nuclear division, varieties in species as well as many 

 species for comparison should be worked upon. 



The dimensions of the vegetative cells of these 3 varieties of 

 5. bellis Hass., and conforming to 5. bellis as described by Collins 

 (2), are as follows: 



Var. A.— Vegetative filaments 57 ju in diameter, 95 n in length, 

 3 or 4 spirals in the filament. This was gathered from the margin 

 of a brook in which was intermingled S. longata, S. inflate, S. 

 gracilis, at Northfield, Massachusetts. 



Var. B.— Vegetative filaments 64 n in diameter, 220 n in length, 

 5 spirals in the chromatophore, the latter markedly dentate; border 

 of river in Needham, Massachusetts. This was not a pure culture 

 of Spirogyra, but intermingled were various filamentous desmids 

 and Mougeotia. 



Var. C— Vegetative filaments 60 ju in diameter, 220 n in length, 

 uniformly longer than B and much longer than A; some threads 



