980 THE AMERICAN NATURALIST. [VOL. XXXIII. 
water) produces a solution which affects unfertilized eggs in the 
same way as the entrance of a spermatozoan does. Eggs of the sea 
urchin, when left in this solution for about two hours and then trans- 
ferred to normal sea water, formed gastrulz and plutei normal in 
every respect. In the experiment fewer eggs developed, and their 
development was slower than under normal conditions. This experi- 
ment shows that the unfertilized egg of the sea urchin contains all 
the essential elements for the production of a perfect pluteus. The 
reason that sea urchin eggs do not develop parthenogenetically under 
normal conditions is the constitution of the sea water; this either 
lacks the presence of a sufficient number of ions necessary for cell 
division (magnesium, potassium, hydroxyl, or others) or it contains 
too many unfavorable ions (calcium, sodium, or others). All the 
spermatozoan needs to carry into the egg for fertilization are ions 
to supplement one class of substances or counteract the other or 
both. The spermatozoan may of course also carry in other mate- 
rials, enzymes, etc. The author concludes this interesting paper 
with the suggestion that possibly parthenogenesis in mammals is 
prevented by the ions of the mammalian blood. G HP 
Notes. — The concluding number of the Zod/ogical Bulletin contains 
the following articles: ‘‘ The Mesenterial Filaments in Zoanthus so- 
ciatus,” by J. P. McMurrich; ‘‘ The Unpaired Ectodermal Structures 
of the Antennata,’’ by M. M. Enteman; “Synopsis of the Callipho- 
rine of the United States,” by G. de N. Hough; and “The Acces- 
sory Bladders of the Testudinata,” by F. W. Pickel. It has been 
announced that the Buletin will be continued under the name of 
the Biological Bulletin. : 
A Biological Survey of Mount Shasta, California, has been under- 
taken by the United States Department of Agriculture, and has been 
reported upon in North American Fauna, No. 16. The general fea- 
tures of the mountain, the forests and forest fires, the life zones, the 
mammals, birds, and plants of the region are described and the fac- 
tors influencing distribution are discussed. 
BOTANY. 
Botanical Papers at the British Association.— Some of the 
papers presented before the botanical section of the British Asso- 
ciation were of unusual importance, and the average merit of the 
