582 ROBERT T. HANCE 



The methods of technique practiced here gave results con- 

 sistent with others obtained in this Laboratory and are part of 

 a number of experiments, employing the same reagents, under 

 similar conditions. 



OBSERVATIONS 



Miss Taylor ('15) states that she had trouble in finding somatic 

 mitoses, but I have had very little difficulty in locating active 

 cells. The cells of the general tissues of the body are usually 

 in a resting condition, but the limb buds in the thoracic region 

 and the nervous tissue are frequently full of division figures. 

 It is an interesting fact that the somatic divisions show some 

 indication of rhythms of cell activity. The tissue may be 

 entirely inactive or, when active, a large number of cells are 

 taking part, and the majority of these cells will be in approxi- 

 mately the same stage of division. 



I have never found any evidence of synizesis in either germ 

 or somatic tissue, except in cases where the material was obvi- 

 ously very poorly fixed. While it seems evident that there must 

 be some physiological (or probably only physical) peculiarity 

 about the stage in which synizesis is observed which permits it 

 to act differently to the other stages, nevertheless, I believe 

 that the actual appearance of synizesis in fixed material to be 

 an artefact. 



Although most of the drawings have been made from mitoses 

 found in the nervous tissue, similar stages have been found in most 

 of the tissues of the body. These include nervous tissue, limb 

 buds, intestine, epithelium, ovarian tissue and Malphigian tubules. 



Prophase. The somatic cell in the resting or early prophase 

 condition possesses a nucleolus. This disappears as the chromo- 

 some filaments appear. The earliest prophase stages I have 

 found in active tissue are shown in figures 2 to 16. As can be 

 seen there are three pairs of threads (two long pairs and one 

 shorter pair) present, all more or less closely associated. The 

 importance of the proper fixation in these stages can not be over- 

 emphasized as I was misled for some time by finding (in the 



