1918] _ PFEIFFER—THISMIA 361 
Thismia clandestina. The endosperm is packed with reserve 
material at this time, and stains very deeply as a result. 
The development of the nucellus and integument into peculiar 
layers has been noted under the literature of other forms. In 
Thismia americana there is also at maturity a distinct mass of 
irregular small cells at the base connecting by means of a dark 
staining nucellar layer with a cap of peculiar cells at the micropylar 
end. The nucellar layer next to the endosperm shows fungal 
hyphae and many oil bodies as part of the contents. Gelatinization 
of the walls at the chalazal end begins early, and is responsible to 
some extent for the prominence of the mass of cells at that end. 
Enough material has not been available to try a satisfactorily 
large range of germination experiments. Those which have been 
tested have given negative results. In all probability, as in orchids, 
the fungus plays a réle in the early development of the plant. 
Summary 
1. In the microsporangia the sporogenous cells develop from 
hypodermal masses, 4 in number, in the usual fashion. 
2. At maturity the innermost parietal layer appears crushed by 
the large tapetal cells. 
3. There is marked abortion of sporogenous cells in the micro- 
sporangia. 
4. The division of the megaspore mother cells gives rise to 
4 megaspores, the outer 2 oriented at right angles to the long axis 
of the ovule. 
5. The 3 outer megaspores degenerate very soon, disappearing 
entirely after a short time. 
6. The functional megaspore divides in the usual way, so that 
eventually an embryo sac of 8 nuclei is produced. 
7. Presence of pollen tubes makes fertilization seem likely. 
8. The well developed embryo is imbedded in large endosperm 
cells which are conspicuous in storage contents. 
g. In the seed the nucellus makes a conspicuous layer, develop- 
ing into a cap of tissue at each end. 
University or Nortu DaKkotTa 
Granp Forks, N.D. 
