Nov., 1922] LEVINE LAMELLAE IN AGARICUS CAMPESTRIS 525 
BB represents the section shown in figure 78, where the two Anlagen of the 
gill cavities shown in figure 77 have opened and the two halves of the 
adjacent verticals of the arch form the gill; at the same time on both sides 
of these two gill cavities appear the eccentric views of two more gill cavities 
which are shown in figure 79, the approximate location of the section being 
represented in the diagram by the line CC. 
Secondary Gills 
In buttons slightly older than those previously described we can study 
the origin of secondary gills. The origin of these gills is of special interest 
since the inner end of the gill often appears in a single longitudinal section 
(Douglas, 1916, fig. 50) as a narrow gill apparently growing downward into 
the gill cavity. The secondary gills are merely short gills extending from 
the margin of the pileus part way to the stipe. 
In diagram 4 we have a primary gill and two shorter ones superimposed. 
The line A cuts through the primary gill which extends from the stipe to 
the margin of the pileus, and its width is represented in diagram 5, A. 
Here we have the full width of the gill. The line 5, diagram 4, cuts through 
the primary and one of the secondary gills, and the widths of the two gills 
are shown in diagram 5, -S. The secondary gill through the region B is 
narrower than we find it at C. Here the primary and the secondary gill 
are of the same width. Similarly, we find the shortest gill narrower than 
the two preceding gills through D, but it becomes of equal width in the 
plane E. 
Coprinus ephemerus is especially favorable material because of the small 
number of gills and the relatively late appearance of the secondary gills. 
Their development is entirely similar to that I have already described for 
Coprinus micaceus. In the tangential section shown in figure 81 we are 
near the margin, as shown in diagram 6 by the line BB. In this section 
we find a narrow gill. The second gill cavity from the left shown in figure 
82 represents the left-end one in figure 81 , and the third gill cavity represents 
the larger middle one in which the secondary or short gill appears to hang 
freely in figure 81. This short gill is not actually free through all its length 
as it would be if it were developing and growing down into the gill chamber, 
for in the succeeding parallel tangential section shown in figure 80, made 
toward the outer surface of the carpophore at a region indicated by the 
line A A in diagram 6, we have the four Anlagen of the gill cavities and the 
younger or marginal part of the secondary gill firmly joined to the funda- 
mental tissue below. Notice how closely the two middle gill-cavity Anlagen 
lie to one another. The crowded condition is indicative of the development 
of a gill cavity in a space which formerly allowed only one. The tramal 
region recognizable between the Anlagen of the other gill cavities is much 
greater and wider, showing an undisturbed condition since no new cavities 
are forming. 
