Miscellaneous. 541 



Wanting this instrument however, I was compelled wfeSN^ftrJi^^flfe 

 to comparative descriptions, which your reviewer allows to have thetf 

 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 totally 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 corpparative 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 oiBotrydium 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. 



It now 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 i\\ 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 Algse 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. ' '^ '^ 

 1st. "A more prominent reference might have been made to the 

 very successful labours of Mr. Ralfs upon this family, and also the 

 Diatomacea, 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 



