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impression is given that their whole development takes place after 
the escape of the sperm-cells from the antheridium, which, to say 
the least, is improbable. At any rate, no account is given of their 
origin and development beyond a very brief statement of the 
changes in the appearance of the sperm-cells from the time they 
are ejected to the escape of the spermatozoids, a period varying 
from one-quarter to one-half hour. 
The development of the archegonium corresponds, so far as 
the somewhat incomplete account goes, with that of other ferns. 
The neck, to judge from the figures, as nothing is said in this 
point in the text, is straight, as in the Osmundacee and Hymeno- 
phyllacee. The number of canal-cells is not given, and no 
mention is made of a ventral canal-cell, although unquestionably 
one must be present. 
The same vagueness is noticed in his treatment of the embryo. 
After stating that the first division-wall is slightly inclined to the 
axis of the archegonium and that the next divisions result in the 
formation of octants, as in the other Filicineze, he says: “ Peu 
a peu l’embryon devient un corps globuleux, A petites cellules, 
dans léquels ia e.. . la cellule triangulaire du sommet de la racine 
est la premiére a se différencier nettement.” 
Sometimes more than one embryo will begin to form upon the 
same prothallium. 
A study of the growth of the root confirms Nigeli and 
Leitgeb’s statements as to the origin of the primary tissues of the 
root, rather than the recent account of Van Tieghem and Doiiliot. 
While the paper is a valuable contribution to our knowledge 
of the ferns, it would have been quite as much so if a large part 
of the very tedious introductory matter were omitted; and it is 
much to be regretted that the account of the sexual organs and 
the embryo is not more careful and complete, as a comparison 
of these with other ferns might be of great value froma systemat- 
ic standpoint. Douc.Las H. CAMPBELL. 
Assimilation of the Free Nitrogen of the Air by Legumin- 
ous Plants. Inthe Berichte der deutschen Bot. Gesellschaft of 
November last, Dr. Frank gives the result of an experiment on 
Robinia Pseudacacia. The soil for this purpose was pure quartz 
sand, first heated, then washed with water containing hydrochlor- 
