The Conjugation o/Zygogonium ericetorum K'utz. 249 
the principle first enunciated by Palla (6)—that chloroplast- 
characters rather than modes of conjugation should he used in the 
grouping of the various filamentous Conjugates—he accepted, then 
the character in question is not of more than generic importance. 
There seems now no reason to doubt that Zygogoninm erice¬ 
torum, on account of its mode of conjugation, must be placed in a 
genus apart from Zygnema. One must therefore either accept 
de Bary’s emendation of Kutzing’s genus “ Zygogoninm —as is done, 
for instance, by Wille (12, 13) and Borge (1), solely on the evidence 
brought forward by de Bary—or else create an entirely new genus 
for the alga. The latter course is highly undesirable, as it would 
only complicate matters further; and, as it has been abundantly 
shown (10, 8) that Kutzing’s genus is untenable, there seems no 
reason why the Zygogoninm of de Bary should not take its place. 
West and Starkey (10) wrote that the “ available evidence does not 
support the retention of Zygogoninm on the basis put forward by 
de Bary (1858) and Wide (1909).” The observations given above, 
however, appear to supply the required evidence, so that if the 
genus is retained at ad it must be as Zygogoninm (Kiitz.) emend, 
de Bary. 
It may be noted, in conclusion, that the terrestrial form of 
Z. ericetorum never seems to have been recorded in conjugation 
before. Rabenhorst (7) states that the terrestrial forms of Zygog. 
Agardh. Rabenh. (=Z. ericetorum) are always sterile. Cooke (2) 
follows Rabenhorst, and says that some forms of Zygog. ericetorum 
are “ terrestrial and always sterile, others aquatic producing 
zygospores.” The above thus seems to be the first record of the 
terrestrial Z. ericetorum being found in conjugation. It is highly 
desirable that conjugating specimens of the aquatic form of the 
alga should be found and compared with what is described above 
It may be that the methods of conjugation of the two forms 
are not quite identical. For instance, the inner wad of the 
gametangium, described above—but not mentioned by de Bary, 
whose specimens were apparently of the aquatic form—may con¬ 
ceivably not be formed in the aquatic Z. ericetorum, in which the 
gametes would not be in need of such efficient means of protection 
against desiccation as they would be in the terrestrial form. 
IV. Summary. 
1. The conjugation of the terrestrial form or Zygogoninm 
Zygnema) ericetorum has been observed, and is described. 
2. De Bary’s account of the conjugation of this alga (under 
