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POPULAR SCIENCE REVIEW. 
not ‘ fallen to the lot ’ of ordinary microscopists to behold, either in twenty 
or in four times twenty years.” For the signification of these miraculous 
circumstances we are referred to the following passage in Professor 
Wilson’s paper : — “The result of these investigations shows the necessity 
of finely divided silica in the soil, so minute as to he capable of passing 
with facility through the sap cells ; secondly, that simple or compound 
silicates are useless as fertilizing agents, either natural or artificially pre- 
pared, ” which, as interpreted by his critic, means “ If you want to raise 
good crops , buy our finely divided silica.” 
The Spermatozoa of Ampkiuma. — These have been examined by Dr. C. 
Johnston, who has contributed a paper on the subject to the “Monthly 
Microscopical Journal ” (August, 1876). He says that “ several matters of 
interest were observed — the structure of the spermatic particles, the dimen- 
sions of their parts, and the length of the filaments. The total length of 
each spermatozoon was ~ of an inch. It begins at the moderately acute 
point of an elongated conical head — ^ of an inch in length by y— of an 
inch in thickness ; behind which the body, slightly more attenuate, ended 
almost into the vague. The ‘ head ’ presented a small curve ; but the body 
lay straight at times, or else threw itself into serpentine flexuosities. A 
Tolies’ recent ~ immersion objective, with that maker’s £-inch ocular, dis- 
played many new points. The head, highly refractive and firmer than the 
other part, appeared to consist of a lamina of homogeneous substance bent 
along its axis, the two tumid edges of which met on the ventral side. 
Anteriorly these edges were suddenly bevelled away, and were lost by con- 
tinuity in a delicate filament ending in a faint swelling. Posteriorly the 
edges contracted at the junction with the body, but were seen to be con- 
tinuous with two cords which had the same relation as their originals in the 
head. They lay close together, and from them sprang the dorsal arch, along 
the ridge of which the propelling membrane was attached. This delicate 
film extended like a ruffle from the posterior extremity of the head as far as 
the caudal point ; the main part was, however, invisible, but not so the 
margin, which was bordered with a thickened hem. In a dry preparation 
the spermatozoids and their details were somewhat deformed, distorted, and 
spread out ; still the characteristics of Amphiuma’s seminal particles were 
very manifest when studied with a fine objective. Thus the edges of the 
cephalic folds and the somatic cords assumed a beaded appearance, as did 
also the collapsed arch-fold of the back along its margin. Yet the eye was 
not satisfied with the dried potential male elements, and reverted with con- 
tinually renewed pleasure to the moving zooids.” 
MINERALOGY. 
Neio Vanadium Minerals. — Professor Roscoe has lately described (“ Proc. 
Roy. Soc.”). a new mineral containing vanadium, under the name of Mot- 
ramite , in allusion to one of the localities from which it has been obtained. 
It forms a crystalline incrustation not more than ^ to ^ inch in thickness, 
but usually much thinner, coating Keuper sandstone. Occasionally it occurs 
