26o CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



genetic fibres, are more difficult to stain than other constitu- 

 ents of the cell, search was made for a stain which should 

 differentiate these structures sharply. Out of the exten- 

 sive series of stains tested, gentian violet proved the best, 

 especially when combined with safranin and orange G in 

 the Flemming triple stain. Benda's iron-hasmatoxylin, 

 used in combination with Bordeaux red, congo red, or 

 ruthenium red, gives good results in the study of non-kino- 

 plasmic elements. The use of gentian violet is attended 

 with some difficulties ; in many cases sections can be left 

 but a short time in the violet, and it is then found that the 

 absolute alcohol washes out the violet too rapidly. This 

 may be avoided by dissolving enough gentian violet in the 

 absolute alcohol to make a saturated solution. The wash- 

 ing out of the violet can then be done entirely by means of 

 clove or anilin oil (either pure or diluted with xylol), and 

 this in many cases is of great advantage. Dipping the 

 slides from two to twenty seconds in dilute potassium- 

 iodide-iodine solution just before transferring to absolute 

 alcohol was found in man}^ cases to give a sharper differ- 

 entiation of all the structures stained by the violet. 



The intense illumination necessary for work with high 

 oculars was secured by using a Welsbach light, and inter- 

 posing a glass globe (about six inches in diameter) between 

 it and the mirror. The globe, being filled with a colored 

 solution, acted as a light filter and condenser; by changing 

 the solution the same preparation could be studied with 

 several different kinds of light. Many details were 

 observed in this way which are hardly visible with white 

 cloud illumination. 



II. Spindle Formation in Agave. 



First Mitosis. 



The species studied is Agave afuericana L. The material 

 was fixed in the field; the best results were obtained with 

 Flemming's strong mixture. Flemming's triple stain was 

 used almost exclusively. 



