354 BOTANICAL GAZETTE [NOVEMBER 
guished from the globules represented in jigs. 42-44. If any of these 
granules represent the chromatin, the individuality of the chromo- 
somes would appear to be hopelessly lost. No satisfactory study of 
the living nucleus was made. A nucleolus is visible in living material, 
but otherwise the contents seem nearly homogeneous. There are few 
globules and the network could not be identified. It is possible that 
most of the globules and the network are coagulation artifacts due to 
fixing. : 
The development of the egg nucleus seems to be essentially the same 
in all gymnosperms. Among the investigators who have studied this 
nucleus in various gymnosperms may be mentioned STRASBURGER (19, 
20), IkENo (10), BLACKMAN (1), CHAMBERLAIN (2), FERGUSON (7), 
and LAND (11). BLACKMAN, CHAMBERLAIN, and FERGUSON attempted 
to follow the behavior of the chromatin, but the accounts are inade- 
quate, there being stages in which all fail to identify convincingly the 
chromatin. Miss Fercuson’s beautiful figures of Pinus show the 
familiar structures with great accuracy, but just what structures are 
chromatin is not clear. My own series of Pinus is less complete, and 
those of other writers are still more incomplete. In Dioon it is 
evident that this nucleus behaves much as in Pinus. The solution 
of the problem is not easily attained in cycads on account of the 
inaccessibility of material and the difficult sectioning. In Pinus, 
with its abundant material and easy technique, a close series in the 
development of the nucleus and in the formation of the spirem at the 
time of fertilization would probably lead to an understanding of the 
egg nucleus of the whole group. 
SUMMARY. 
1. Dioon occurs in abundance at Chavarrillo, Mexico. 
2. It is probable that plants often reach an age of more than one 
thousand years. 
3. The ovulate strobilus is more like the loose ovulate strobilus 
of Cycas than the compact ovulate strobili of the other genera. 
4. The megasporophylls are more leaf-like than those of any 
other genus of cycads except Cycas. 
5. The integument consists of three layers: an outer and an 
inner fleshy layer, with a stony layer between them. The integu- 
