538 Fraser and Brooks — Further Studies on the 
Humaria granulata. 
Fertilization in Humaria granulata was studied by Professor V. H. 
Blackman and one of ourselves (2) in 1906 ; no antheridium was observed, 
but the female nuclei were seen to fuse in pairs in the ascogonium. 
The first division in the ascus is characterized by synaptic stages 
(PL XXXIX, Figs. 4, 5), and the chromosomes assume the various forms 
(Vs, Y’s, X’s, &c.) which indicate the occurrence of meiotic reduction (Figs. 
6 , 7) ; the material, however, did not lend itself to the discrimination of the 
finer details of this process. The number of chromosomes on the spindle 
in the metaphase is eight (Fig. 8), and eight travel to each pole (Fig. 9). 
In the second division four chromosomes appear (Fig. 10), and the 
same number is distributed to each of the daughter-nuclei (Fig. it). The 
third division closely resembles the second, and the number of chromosomes 
is the same (Figs. 12, 13). A brachymeiotic reduction is thus accomplished, 
the number of chromosomes present in the heterotype telophase is reduced 
to half, and the gametophytic number becomes evident. We did not 
satisfy ourselves of the occurrence of contraction phases in connexion with 
either the second or the third mitosis, for in Humaria granul at a no definite 
spireme was demonstrated at this stage, but the stainable material was 
aggregated in an irregular mass occupying part, usually the centre, of 
the nuclear area. 
In Humaria granulata the divisions in the ascogenous hypha are very 
clear, and we succeeded in counting the number of chromosomes here also. 
Four are present in the early metaphase (Fig. 1), and in the anaphase four 
are found travelling to each pole. Four is the gametophytic number in 
this fungus, and we therefore at first inferred that we were dealing with 
a specimen in which fertilization had not occurred, or in which, as 
Claussen ( 3 ) suggests, mere nuclear approximation and not fusion had taken 
place in the ascogonium. 
Not only, however, has the fusion of sexual nuclei been already 
observed in a number of ascogonia (Blackman and Fraser ( 2 )), but the 
ascus itself shows two reduction stages : first, the synapses and gemini which 
are generally accepted as characterizing meiosis, and, secondly, in a sub- 
sequent division, the numerical change from eight chromosomes to four. 
Consequently, as the number of our examples of division in the ascogenous 
hyphae increased, we were led to the conclusion that in Humaria granu- 
lata , as in Phyllactinia (Harper ( 12 )), and in certain other organisms the 
chromosomes become associated in pairs at the time of fertilization, and the 
sporophyte therefore shows four bivalent instead of eight univalent chromo- 
somes. 1 
1 It is perhaps worth noting that the only other possible interpretation, that which denies the 
fusion in the ascogonium, must also discard the meiotic reduction, for the change in the number 
