178 BOTANICAL GAZETTE | SEPTEMBER 
the structure of bodies so extremely small can hardly be over- 
estimated. 
With either a Bausch & Lomb +, oil immersion objective and 
3 ocular, or a Zeiss oil immersion 2™" and ocular 3, I was able 
to make out the spermatozoids only by their characteristic rotary 
movements as they left the microspore of S. rupestris. Their 
spiral form and attached vesicles were facts determined rather 
by interpreting appearances by those I had definitely seen in 
apparently similar but larger bodies, than by actual observa- 
tions. The spermatozoids of S. apus are somewhat larger, and I 
feel that there is less likelihood of error in describing them. It 
is obvious that a more critical examination of many species is 
needed before much weight be placed upon the so-called aberrant 
forms of the Selaginella spermatozoids in tracing the phylogeny 
of the group. 
THE DEVELOPMENT OF THE SPORANGIA.—The two most recent 
and important papers on the development of the sporangium are 
Goebel’s (1880) and Bower’s (1894). I shall quote verbatim 
Bower’s summary of results from Selaginella: 
1. The sporangium is eusporangiate, and arises from the tissue of the 
axis, above the subtending leaf; the position varies in different species. 
2. The origin of the sporangium is similar to that of Lycopodium, and 
especially resembles ZL. zxundatum, to which species the mature sporangium 
also is similar in form. 
3. Two primary archesporial cells are usually present in each radial sec- 
tion, and these are derived, as in ZL. inundatum, from segmentation of two 
distinct cell-rows; as seen in tangential section, the archesporium is refer- 
able to three or four such cell-rows. 
4. The first periclinal divisions in these cell-rows do not always define 
the archesporium finally; subsequent periclinal divisions may result in addi- 
tion to the central mass, as has been proved for Equisetum ; but here the 
addition is less regular. 
5. The tapetum results from tangential division of the outermost cells 
of the central mass; the greater part of it originates as described by 
Goebel 
_ The tapetum is thus a sterilized part of the potential sporogenous 
tissue; a further example of sterilization is seen in the megasporangium, 
where all the sporogenous cells are disorganized, excepting the one mother 
cell of the megaspores. 
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