6o 
Debarya cruciata : a Correction. 
might also be traced. Wherever gemini are formed we are bound 
to assume an attraction between homologous chromosomes sufficient 
to bring about the union of these in pairs. This attraction may 
supervene as soon as nuclear fusion has occurred (or at some stage 
shortly after) and may thus induce the formation of an apparently 
single structure as in Phyllcictinia or of such a double spireme as 
Overton and others have described in the cells of the angiosperm 
sporophyte. The observations of Muller already referred to suggest 
that the members of each pair may remain in relation throughout 
the phases of vegetative mitosis. 
In other cases it seems clear that the pairing of the chromo¬ 
somes is postponed till the later prophases of the heterotype division; 
under these circumstances we shall not expect to find any evidence of 
chromosome association previous to the formation of the gemini. 
The question must arise whether interaction or interchange 
between the paternal and maternal nuclear elements takes place 
more extensively when chromosome association occurs early than 
when it takes place only at the onset of meiosis. A study of the 
nuclear elements from this point of view would be of special interest 
in organisms where well-marked segregation of allelomorphic 
characters takes place. Indeed, it may be tentatively suggested 
that the clearest cases of Mendelian inheritance will perhaps be 
those correlated with a late association of the chromosomes in pairs. 
H.C.I.F. 
DEBARYA CRUCIATA : a Correction. 
There are a few points in the description of Debarya cruciata 
sp. nov. 1 which require correction. I am indebted to Professor 
West for informing me of this. The material was mixed with a 
quantity of two species of Mougeotia, namely M. gracillima and a 
little M. viridis, and unfortunately the sterile cells of these were 
mistaken for those of the Debarya. The sterile cells of the latter 
were very scarce in the material, but revised measurements show 
that the filaments are thicker than those of D. desmidioides West. 
There are, moreover, always two pyrenoids in the chloroplast. 
Although usually conjugation is between isolated cells of the 
filament, yet in a few cases zygospores are formed in contact. 
A revised diagnosis is therefore appended:— 
Debarya cruciata char, emend. 
D. filamentis longis salpe dissociatis in cellulis singulis; cellulis 
vegetativis cylindricis, lateribus rectis, diametro 4-7-plo longioribus; 
chromatophoris cum pyrenoidihus 2. 
* Price, S. R. New Phyt., Vol. X, p. 87. 
