AECHER — ON " PALM0GL03AN \LG1E." 265 



teristics of the forms themselves as of specific importance. The special 

 characters, which, as I think, here determine the genera, exist in the 

 peculiar arrangement of the contents, combined with certain of the ge- 

 neral characters previously alluded to ; whilst I believe the specific cha- 

 racters reside in the peculiar form of the cell, and in minor differences 

 in the arrangement of the contents, and in difference of colour, &c, 

 perceptible to the unassisted eye in the general mass or stratum. 



Again, Dr. Hicks seems to convey, because of the difficulty (for the 

 reasons before stated) of assigning some of these forms to the particular 

 ones described under Palmogloea by Kiitzing, and from there having 

 been actually (as I conceive) included under that common generic deno- 

 mination five diverse types, that therefore "no one algologist can tell 

 distinctly what is a Palmogloea, so as to be understood by any other algo- 

 logist." I venture deferentially to deprecate this,, as it appears to me 

 much too hasty a conclusion. I must, in reply, urge that if many of 

 the now well-established species formerly comprehended under the old 

 incongruous genus Conferva were still referred to under their original 

 designations, and recent researches upon the forms alluded to momen- 

 tarily forgotten or ignored, that it is still more probable no one algologist 

 could, under such circumstances, tell what was meant by another algolo- 

 gist. But, if our plants be closely examined from the living examples, 

 and de Bary's descriptions and figures thereof carefully studied by any 

 two algologists, I hardly think there will be any difficulty between them 

 in understanding what the other means when he refers to a Cylindro- 

 cystis, a Mesotaenium, or a Spirotsenia. 



" Dr. Hicks does not see how I can find sufficient ground to state that 

 the condition of a developing lichen figured by him is not a " macro- 

 cocca" — that is, as I am disposed to think more correctly designated, 

 an example of Mesotcenium chlamydosporum (de Bary). I judge from 

 the figure ; and I think, as I stated, because it seems to me, so far as I 

 may venture to judge, to represent something at once sufficiently unlike 

 both the form with which I am acquainted, as well as Kiitzing's de- 

 scription and figures of his P. macrococca, as to justify me in that as- 

 sumption. 



Again, as if it were to a certain extent evidence of the total instabi- 

 lity of these forms, Dr. Hicks alludes to my being by no means certain 

 what he means by Palmogloea Brebissonii, because I questioned whe- 

 ther the plant he has in view as Palmogloea macrococca is the same as 

 Palmella cylindrospora (Breb.), considered by Mr. Ealfs as equivalent to 

 his Penium Brebissonii, and of which Dr. Hicks writes : — " So far as 

 can be ascertained, Mr. Thwaites calls Coccochloris Brebissonii, although 

 Mr. Archer thinks he means Trichodictyon rupestre (Kutz.) ; the exact 

 characters of this form, it will thus be seen, are by no means settled by 

 anyone of these observers." Dr. Hicks writes, indeed, " this form ;" but 

 the supposed confusion is partly accounted for by the fact, that there 

 are two distinct forms referred to under the foregoing names, and two 

 forms which, as I hold, when once seen cannot readily again be con- 

 founded ; for, even though the characters assigned to each should not be 



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