DUBLIN NATUBAL HISTORY SOCIETY. 149 



ADJOURNED MEETING, APRIL 17, 1857. 



Peofessoe "W. H. Haevey, M.D., M.R.I.A., F.L.S., President, 

 in the Chair. 



The Minutes having heen read and signed, — 



De. William Feazee read the following — 



on a disease in hyacinth eoots, caused by ceyptogamic geowths. 



Pew subjects are more difficult to follow satisfactorily than the de- 

 velopment of the minuter forms of cryptogamic plants, and few, therefore, 

 are enveloped in greater obscurity ; unlike the sea- weed or the fern, 

 which, from their gracefulness and beauty, at once attract our attention, 

 the subject of my present remarks are by many considered to be pecu- 

 liarly repulsive, and are associated in the mind with ideas of disease 

 and decay ; and although I must in fairness claim for some of them as 

 full a share of beauty in external form as has, perhaps, been granted to 

 any class of plants, still I cannot deny their frequent connexion with 

 putrescent changes. 



The exact nature of this connexion has been made the subject of 

 many inquiries. Some have altogether denied that there was any real 

 sequence between the development of these fungi and the disintegration 

 of the organized tissues upon which they are found, considering their 

 presence merely accidental, or at best of secondary importance, perhaps 

 even useful in consuming the decaying particles ; whilst others have at- 

 tributed the changes which ensue in the rotting mass exclusively to 

 their agency. 



Much of the writings on this subject can be of little or no value, be- 

 ing mere theoretic ideas, without sufficient facts to warrant their recep- 

 tion ; still, after laying these aside, we have a number of positive 

 observations to aid us in determining the truth of those extreme opi- 

 nions, and, as in many other matters, it appears to lie midway between 

 both. To the microscope we owe much of what has already been 

 accomplished in the investigation of these interesting growths and the 

 study of their development, and amongst other remarkable advances in 

 our knowledge we have ascertained by its agency that those lower forms 

 of vegetable life, unlike the higher plants, may have, instead of a single 

 kind of fructification, two, three, four, or even five different modes of 

 reproduction ; and also that, in place of a uniform manner of develop- 

 ing their structure, they may assume various states under different con- 

 ditions, so unlike each other that nothing but the most ample evidence 

 would enable us to connect them. 



To illustrate my meaning I would merely mention the common and 

 worthless blue mould, Penicillium glaucum, which is considered by our 

 best observers to constitute in another form the well-known yeast plant, 

 or barm, Torula cerevisice, so important in the process of fermentation 

 and in making bread; and in still another state it develops into the 



