22 HE MICROSCOPE. 
several nuclei. He holds this condition to be normal, and considers 
the statement of Einhorn, who examined dry blood preparations, 
that in normal blood the number of single nucleated leucocytes 
is much less than the multi-nucleated, to be false. 
Spore-DisseMination oF Equisrrum.—From a careful examina- 
tion of E. avense and hyemale, Newcombe (Botanical Gazette, July, 
1888) arrives at the following conclusions: (1). The first step in spore- 
dissemination is the separation of the sporangia-bearing scales by the 
elongation of the axis of the spike, thus allowing free circulation of air 
for drying spores and sporangia, and providing open spaces for the 
escape of the spores after dehiscence of the dry sporangia. (2). The 
comparatively straight columns or rows of transverse cells in the ven- 
tral walls of the sporangium, together with the thinning out of the 
wal] in this region, furnishes a line of weakness which becomes the 
line of dehiscence. Moreover, the unequal contraction in length and 
width of the strong external layer of cells of the sporangium-wall 
results in a greater shortening of the dorsal wall and a slight 
shortening of the ventral wall, thus causing a wide opening in the 
ruptured sporangium for the passage of the spores. The hydro- 
scopic properties of the elaters seem to be satisfactorily explained 
by the difference in chemical composition of the two layers 
composing them. The function of the elaters is two-fold: (1). To 
push the spores out of the sporangia. (2). To furnish sails for 
catching the wind, by which the spores are distributed. Contrary 
to other observers, Newcombe finds that the sporangium wall 
contains three or four layers of cells, instead of one, and the reason 
that these have escaped observation seems to be because of the 
difficulty in detecting them by looking down upon or through the 
sporangium-wall. In sections of the sporangium the inner layers 
of cells become clearly visible. 
Karta Worms.—N. Kulagin communicates (Zool. Anzeiger, 
XI, 231, American Naturalist) some observations on Russian 
earth worms which are worthy of note. The cuticle, composed of 
H., C.,O. and N., is not a true chitin, but might be called a 
precurser of it. It dissolves readily in weak HCl, and other acids, 
and to prevent this effect by the humus acids in which the worm 
lives, the ectodermal glands secrete an alkaline fluid. The egg 
cocoons differ much, as they withstand strong acids and pepsin. 
The fiuid of the mouth and pharynx has an alkaline reaction, and 
converts starch into sugar and fibrin into peptone. The cale-glands 
