Nov., 1914.] Stamens of Smilax herbacea. 359 



spirem was discernible at this time and at intervals the spirera, 

 which is made up of previously paired chromatin elements, was 

 constricted in some places to a narrow thread and finally separated 

 into irregularly shaped double segments. These pieces continue 

 to thicken and shorten, forming X and V-shaped chromosomes. 

 She says that the first division is merely a separation of the 

 chromosomes, but the second is a true mitosis. A.t the telophase, 

 she observed that the spirem was disposed about the periphery 

 of the newly formed membrane. The nuclear membrane dis- 

 appears and the spirem is spread out over the spindle and in a 

 short time the spirem contracts into the equatorial plane, dividing 

 into chromosomes which become attached to the spindle with 

 the open ends outward. She could not determine the exact 

 number of chromosomes, but decided that there were either 

 twelve or thirteen. 



Schaffner found in his study of Er^'thronium that the spirem 

 was at first long, slender, with chrornatin granules that are not 

 prominent before the looping. The spirem undergoes a contrac- 

 tion and a preceptible thickening, and is thrown into twelve 

 loops which are apparently broken apart by the twisting and 

 contracting. The chromosomes are said to be of various sizes 

 and seem to be double. They are attached to the spindle near 

 the free ends and during metakinesis are uncoiled and pulled 

 apart in the middle. 



In Lilium tigrinum, (13), he found the chromatin network 

 forming a thin spirem with a single row of spherical granules. 

 There were no free ends so this would point to the fact that the 

 spirem is continuous and is also free in the cavity. The spirem 

 was then found to be in a condition of contraction and there 

 was not any apparent change in the spirem after it had come out 

 of this condition. After this the linin thread is said to elongate. 

 The spirem also has a tendenc}^ to form into loops. Twelve 

 loops are formed which break up into twelve chromosomes. 

 These are attached to the spindle fibers near the free ends in the 

 iTLOther star and are separated by a transverse division. The 

 split in the second division is a longitudinal one. 



When working with Agave virginica (15), he found that 

 there was a course chromatin net present and the cytoplasm 

 was dense and spongy. The chroinatin net stretched out and 

 formed bivalent protochromosoines which in turn formed a 

 delicate spirem with a single row of granules. Synizesis fol- 

 lowed, and in a study of the living material no contraction of the 

 chromatin material was noticeable. After synizesis a transverse 

 division of the chromatin granules takes place with a shortening 

 and thickening of the spirem which is thrown into loops of various 

 sizes and pressed against the wall of the nuclear cavity. With 

 the breaking of the spirem there results three ring chromosornes, 



