RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 129 



fungus with a definite host the true one, there would have 

 been a chance that it would have been possible to make 

 spores from such a parasite germinate and grow in a nutri- 

 tive solution, and I still think that the second mode of ex- 

 plaining the restricted choice of most parasitic fungi as much 

 holds as the first. 



I applied this second method in all kinds of ways in 

 arranging the spores for germination. If I had succeeded in 

 causing the germinating filaments to continue growing in 

 this manner for some time, I should have at once been able 

 to combat the organic individuality of the lichens with a 

 wholly new weapon. 



In the choice of the nutrient fluids for the culture, I 

 supposed that it was best to select such as had been applied 

 with good result for the germination and development of 

 other fungi. From the small number of these fluids I chose 

 the two following : 



(a) Culture fluid, made use of by Boussingault for develop- 

 ment of the Mycoderms} — Milk is coagulated with acetic acid 

 when, all the caseine being deposited, the whey is filtered ; 

 this contains albumen phosphates, potash, soda, lime, mag- 

 nesia, oxide of iron, and water. This fluid, dilated in 

 different degrees with distilled water, was used ; at the same 

 time, in many cases there was added a little ash of the 

 lichens whose spores were to be germinated. 



(b) Pasteur's fluid, used for the development of the 

 Mucedines? — The composition of this culture fluid is : — 

 Distilled water in which is dissolved an ammoniacal salt, 

 sugar-candy, and phosphate, obtained by the combustion of 

 yeast, the last constituent introduced by means of the ash of 

 the lichens. This fluid was also used diluted in different 

 degrees. 



In two different methods, by means of a number of 

 experiments, lasting from 15th April to the middle of June, 

 1872, it was attempted to germinate the spores of Ramalina, 

 Xanthoria, and Lecanora by means of the culture fluid, and, 

 above all, to be made to go on to develop the germinating 

 filaments. 



1. The spores were brought upon a slide with a drop of 

 the fluid, and this placed, in the known manner, in an 

 atmosphere moistened by vapour ; here, likewise, some of the 



' Boussinfrault, "Observ. relat. au Develop, des Mycodermes," 'Comptea 

 Rendus,' 1860, p. 672. 



' Pasteur, "Reclierches sur le mode de Nutrition des Mucedinees," 

 ' Comptes Rendus,' 1860, p. 710. 



