Allen—Spermatogenesis and Apogamy in Ferns. 39 
There may be more material of the same sort in solution in 
the nucleus, hut not all of the substances used in the growth of 
the blepharoplast can have been derived from the recognizable 
nucleolar material of the antherozoid mother cell. 
The question as to the relations of the blepharoplast and cen¬ 
trosome is still an open one. There is considerable evidence 
that the animal centrosome is a permanent structure of the 
cell. The plant blepharoplast as it appears in Archegoniates 
and seed plants is apparently not permanent. It is present 
during a few divisions or perhaps only one. There can be no 
question that after considerable growth and various transforma¬ 
tions, the blepharoplast becomes the structure from which the 
cilia are developed. In this it conforms entirely to the be¬ 
havior of the centrosome in animal spermatogenesis. It seems 
probable that the animal centrosome and the blepharoplast are 
closely related in their essential nature, to the spindle and astral 
fibres and may both be classed under the category of kino- 
plasmic substances. As our knowledge of the various activi¬ 
ties of kinoplasm and of the equally varied forms which it can 
assume, increases, it perhaps becomes less surprising that a 
kinoplasmic organ, similar in form and function to the centro¬ 
some can be formed de novo for a special function. 
In connection with the old question as to the effects of use 
and disuse upon the persistence of a structure, it is interesting 
to note that the majority of the apogamous ferns, including 
Aspidium falcatum ■, still produce normal antherozoids. Yet so 
far as can be judged, apogamy is here an old and well estab¬ 
lished process. Winkler find equal persistence in apogamous 
seed plants. 
The occurrence of substitution fusions in plants that have 
become apogamous is a fact of fundamental importance for the 
interpretation of sexual phenomena. Such cases are apparently 
not uncommon among the fungi but the case reported by 
Farmer and Digby for Lastraea pseudo-mas var. polydactyla 
is the only one hitherto reported for the apogamous ferns. 
There can be no question that as described above, sixteen spore 
mother cells are formed in the spore sac of Aspidium falcatum 
and that these sixteen cells fuse in pairs to form eight. The 
