1^6 Natural History Bulletin. 



It seems that the sporangium is at first divided into four 

 compartments after the manner of an ordinary homosporous 

 fern, and these persist until about the time when the division 

 of the nuclei of the mother-cells is completed. The mother- 

 cell-nuclei also divide into four, each of which develops into 

 a spore, and it is during this division that the karyokinetic 

 figures appear. After a little practice the condition of the 

 nuclei can be estimated at a glance, even without staining, by 

 the presence or absence of the partition wall or the tetrads. 



There are only a few stains that are at all suitable for the 

 demonstration of the structure of the nucleus. Perhaps the 

 best of these is Friedlander's (haltbar) hajmatoxylin, both on 

 account of its permanence and the extreme delicacy of its dif- 

 ferentiating poW'Cr. In order to secure the best results the 

 sections should be placed in a shallow glass dish large enough 

 to admit of their being well separated, and washed in water 

 to remove the alcohol. A considerable amount of distilled 

 water should then be added and the stain, which has been 

 prepared by diluting with fifty to one hundred times its vol- 

 ume of distilled water, poured in and thoroughly diffused. 

 The amount of stain used should vary, not with the amount 

 of water used to immerse the sections, but with the amount of 

 material to be stained. If the right quantity has been taken, 

 the vegetable tissue only will be stained and not a tinge of 

 color will appear either in celloidin or water, after the sections 

 have remained in the solution for twenty-four hours, the time 

 required to obtain a good clear color. Only two or three 

 drops of the concentrated hasmatoxylin solution will be required 

 to stain the sections cut from a single mount. If more is used 

 the section wall be overstained. Understained sections can be 

 brought to the right color by adding a drop or tw^o of stain 

 to the water after it has become clear. 



Even slight acidity of the alcohol used in hardening or the 

 presence of organic impurities in the water makes perfect 

 staining an impossibility. 



Indirect division of the nucleus is not confined to the repro- 



