716 NATURAL HISTORY MISCELLANY. 
to be of the more powerful sex ;” and Thury of Geneva believed — 
that the moment of fertilization relative to the maturity of the 
ovule, exercises a decisive influence on the sexuality of the prod- 
uct, the ovules fertilized earliest producing females, and those 
fecundated at a later period producing males. Professor Hoffmann 
of Giessen has recently attempted to test the truth of this theory 
in the case of dicecious plants, the species on which the experi- 
ments were made being Spinacia oleracea, Mercurialis annua, Iy- 
chius vespertina, and Rumex acetosella. In each case the female 
plants were separated into two portions, one being fertilized arti- 
ficially as early as the stigmas were developed, the other after they 
had been mature for a considerable period. The result of his ex- 
periments was, on the whole, decidedly opposed to Thury’s theory ; 
nevertheless he found that the period of fecundation had an Ur 
mistakable influence on the plant; and also that a remarkable dif- 
ference exists between the results of artificial and of natural im- 
pregnation which he was quite unable to account for.—A. W. B. 
Diaroms 1x THe Hor Sprincs or Nevapa.— Dr. Blake exhib- 
ited, before the California Academy of Sciences, under a powerful . 
microscope, specimens of Diatoms from a hot spring in Nevada, 
the temperature of which was one hundred and sixty degrees. Dr. 
Blake said they were more numerous there than in any other local- 
ity, six or eight hundred occurring in a bit of mud the size of i 
a pin’s head. Most of them were identical with the fossil spece® — 
described by Ehrenberg, from near Salt Lake, but many were D&W 
He mentioned particularly the red alge, living in the spring ani 
found in salt beds in many parts of the world. He found about 
fifty-two species, of which thirty are the same as Ehrenberg’s, WHO : 
mentions about sixty-eight. 
| ZOOLOGY. 
Fossi Mesozoic Mamas.” —The interest which in the ye 
1854 centred around the important discoveries of Mr. ees T 
a small and apparently insignificant seam in a scarcely noticeable 
stratum of the upper Oolitic series has during the past few MOP” 
risen to satisfaction at our k fact that the epee 
nowledge of the m S 
ERED fer r erene emea sa a E AAEE E eae ae a 
* “ Monograph of the Fo olo ] i 
> ssil Mammalia of the Mesozoic Formatio 3 
Owen, F. R. S, D.C. L. (Printed for the Palæontographical Society. erate 
y By professot 
