KOLLIKER, ON VEGETABLE PARASITES. 187 



branes, and would require merely a certain displacement of 

 the molecules of the tissue, which certainly takes place in 

 moist sponge-fibres, as is obvious from their powerfully ab- 

 sorbent property. 



4. With respect to the nature of the parasites, Wedl and 

 I are so far not in accord, that he describes them as multi- 

 cellular plants, and, indeed, as alga, w T hilst I regard them 

 as unicellular fungi. With respect to the uni- or multi- 

 cellular nature of the growths, I think my view is supported 

 by the circumstance, that on the close survey of numerous, 

 and more particularly of the wider canals, no trace of a 

 partition-wall has anywhere been perceptible. Whilst, as 

 to the question of their being Algse or Fungi, it is not for 

 me to give a reply, inasmuch as it is well known that 

 botanists do not find it easy to draw good lines of distinction 

 between the two divisions, and that the first botanical 

 authorities entertain opposite views with respect to certain 

 divisions. ( Vide Nageli, ' Gattung. einzell. Algen/ Zurich, 



1849, pp. 1, 2 ; and Verhandl. d. Deutsch. Naturf. in Bonn; 

 Cohn, ' Entwicklung der niedern Algen und Pilze,' Berlin, 



1850, p. 139 et seq. ; and Pringsheim in Jahr., f. wiss. 

 Botan. 1, 2, p. 284 et seq.) It cannot be denied that the 

 beautiful networks observed in many situations, and analogous 

 to those of the mycelium of fungi, and the mode of fructifica- 

 tion, appear to indicate the fungoid nature of the parasitic 

 growths ; and I shall, therefore, for the present, describe 

 them as such. The naming of them I willingly leave to those 

 who are alone entitled to undertake it. 



Note to the above. By Dr. J. S. Bowerbank, F.R.S., &c. 



I cannot concur with Professor Kolliker in the belief he 

 entertains that the tubular fibrous tissue surrounding the 

 skeleton fibres of the pieces of sponge I gave him are ori- 

 ginated by vegetable parasites. 



The Sporangia, figure 3 in his paper, and other similar 

 forms, are of common occurrence on sponge fibres, where no 

 such network of tubular fibre occurs, the saline matters 

 remaining in sponges always attracting so much moisture, 

 as to cause them to be abundantly infested with parasitic 

 forms of vegetation ; but, notwithstanding these favorable 

 circumstances, I have never met with this curious network 

 but in three species of recent ceratose sponges, although 

 I have examined many hundred specimens of them. Another 

 fact in favour of their being really organic tissues of the 

 sponges is, that very similar canals occur in siliceous sponge 



