1900] ACHROMATIC SPINDLE OF OSMUNDA 363 
0. Claytomana have reached the mother cell stage, in which con- 
dition they lie dormant during the winter. The division into 
spores takes place in the spring, usually in northern Indiana 
between April 15 and. May 1. O. regalis does not reach so 
advanced a condition before winter as do the other species. 
Cell divisions in the sporogenous tissue occur in the spring, and 
itis not till after the middle of April that the mother cells are 
differentiated ; the division into spores is effected about three 
weeks later. 
‘Amore exact statement will be instructive. April 6, material 
collected showed occasional karyokinetic figures in the sporangia. 
April 21, first collection in which no divisions were found in the 
‘porogenous cells; the tapetal cells were in active multiplica- 
tion, May 5, many nuclei were in synapsis, the first seen. May 
10,most of the nuclei were in synapsis, but some in first division. 
May 13, in most cases both divisions were completed, and often 
- trace of the spindle remained.’ This indicates that the rest- 
ng and early spirem stages last for about two weeks, and the 
‘YMapsis stage for three or four days; and that the two divisions 
“eelfected in quick succession within a period of two or three 
days, The difficulty of obtaining the various stages of the second 
tivision also affords evidence that the second division follows 
. quickly after the first, and is completed in a much shorter time. 
© resting mother cell (jig. z) is angular in form, and 
Presents a rather large nucleus. The cytoplasm is evenly dis- 
: tibuted as a delicate network of stainable matter with irregular 
‘Wellings at the points of intersection; it cannot be regarded as 
. mig the Structure of foam. The nucleus has a structure 
aly that of the cytoplasm, differing only in the seo 
a8 =a of its meshes, the larger size of its granular thicken 
"85 and its more intense reactions with stains. Two or three 
cleoli are usually present. In the cytoplasm are numerous 
a Staining granules of variable size, each usually lying a 
: ‘stained area, as if the granules had suffered contraction in 
| be added that the collection of May 13 was not from the same locality 
F earlier dates. 
