Miscellaneous. 141 
Wanting this instrument however, I was compelled to have recourse 
to comparative descriptions, which your reviewer allows to have their 
use provided the objects of comparison be known. Now this admitted 
use I take to be very important and wholly contradictory of the 
paragraph following that which has just been quoted and which I 
here insert :—‘‘ To show the absurdity of such comparative characters 
(a use has just been assigned to them), and how fotally useless a con- 
siderable portion of Mr. Hassall’s definitions of numerous species 
becomes, we will take a single series of species of the genus Zygnema.”’ 
Here follows an enumeration of the comparative size of the filaments 
of several species of Zygnema, isolated from the other portions of the 
description ; the only legitimate conclusion from which is, that other 
characters are required to make up a satisfactory definition, and 
which characters are in my work very generally supplied. Any na- 
turalist studying the genus Zygnema would in a very short period 
become acquainted with a certain number of species, and this know- 
ledge would enable him to appreciate to its full extent the value and 
importance of the comparative characters employed by me. I would 
therefore submit that the definitions of species of the genus Zygnema 
given by me are neither “ totally useless” nor characterized by “ ab- 
surdity.” 
In another portion of your notice of my work, the reviewer takes 
an exception to the figure of Botrydium granulatum and to the genus 
Arthronema. My answers to these strictures are, that the former 
species is a doubtful Alga, and that it had better to have been alto- 
gether omitted from the work; and that the latter genus is one of 
the most distinct of those contained in the family to which it be- 
longs. 
; fe ew remains to me to notice only two other points in the re- 
view ; the first is the opinion of the German reviewer on my views 
respecting the functions performed by the central organs recently 
discovered in the cells of Zygnema, and which he considers to be 
made up of “‘ phantasies and absurdities.” Without pausing to dwell 
upon the unfairness of quoting a discourteous expression of this sort. 
apart from any reference to a single argument or fact in support of 
it, I would merely observe, that it comes with an ill grace from one 
of a people notorious for indulgence in ‘ phantasies and absurdities.” 
Were recrimination desirable, I could name a German naturalist and 
editor who entertains opinions on the reproduction of the Algz not 
less absurd and phantastical than any which I have expressed. 
In the last place I would wish to notice certain expressions of the 
reviewer in reference to the labours of Mr. Ralfs. These I will in- 
troduce before proceeding to comment on them. 
- Ist. “ A more prominent reference might have been made to the 
very successful labours of Mr. Ralfs upon this family, and also the 
Diatomacee, which have appeared in our pages.” 
2nd. “ We do not blame him (Mr. Hassall) for copying these 
beautiful drawings, but he ought to have taken better copies.” __ 
3rd. “We cannot afford time or space to hunt out and record all 
these errors, nor indeed the very many erroneous references to 
