PREFACE. IX 



in a large new work, Les Microzymas dans leurs rapports avec 1'he'te'roge'nie, 1'histio- 

 gdnie, la physiologic et la pathologic, Paris, 1883. 



Theories of the kind here described, and others more or less like them, are 

 constantly recurring from time to time on the subject of the origin of the Fungi and 

 Bacteria. They appeared in earlier times with still greater breadth of application. 

 Fifty years ago it was believed that not only minute organisms but that Fungi of the 

 size of the Uredineae were produced from the altered substance of other organisms, 

 in the case of the Uredineae from phanerogamous plants ; two hundred years 

 ago maggots were supposed to be bred from putrid flesh. It is easy to understand 

 how such ideas of spontaneous generation should have been prevalent in ancient 

 times. Even their repeated recurrence in modern times and with our modern know- 

 ledge is also capable of explanation. It must be assumed that organisms did once 

 come into being of themselves without parents, being produced from organisable but 

 not yet organised matter. It must moreover be allowed, that this may still happen at 

 any moment and perhaps does actually happen ; its impossibility cannot be proved. 

 To produce actual proof of an original formation of a living being is a matter of the 

 highest interest, and has as powerful attraction for the biological investigator, as the 

 prospect of producing the homunculus in the phial for the alchemist. But the 

 experience of centuries has shown that whenever the homunculus really appeared in 

 the flask, it proved to be a small imp which had been secretly introduced into it from 

 without; and speaking seriously, the result was always of this kind. In every single 

 instance exact investigation has shown that the organisms which were supposed to 

 have had no parents proceeded from germs produced from parents of the same species 

 as themselves ; it has also shown how they were formed and whence they came. 

 Those who maintained that direct proof had been given of generation without parents 

 have been driven back step by step into narrower territory, and upon minuter and at 

 last upon the minutest objects, from simple inorganic matter to the organised mini- 

 mum, the ' atome structure* vivant'; in other words they were reduced to seek their proof 

 where it is still most difficult to say whether it is to be found or not. This is what 

 has happened in all researches into the origin of the Fungi, as soon as each individual 

 case was rigidly examined. We have had ocular demonstration of the fact since the 

 year 1860, through the labours especially of Pasteur and his school. That there is 

 no generation without parents is therefore a maxim of experience ; it is in distinct 

 accord with the present state of our knowledge, after making allowance for all 

 conceivable possibilities, and we must set out from this principle in a book which is 

 concerned with real knowledge. 



There is not much to be said by way of preface with regard to the plan of this 

 work. I have endeavoured to make my remarks intelligible even to those who are 

 only beginning the study of the Fungi, but I have assumed that my readers are 

 masters of such a previous general knowledge of botanical science as is to be obtained 

 by a course of study in a University, or by the use of good text-books. The reader 

 is here referred to such works, especially to Sachs' Text-book and Lectures, and 

 Goebel's Outlines, and also to Prantl's and Luerssen's smaller compendia, and among 

 works not in German to Van Tieghem's Traite de Botanique. 



A few descriptions only of individual Fungi will be found scattered through the 

 volume ; others must be sought in our at present imperfect floras, in Saccardo's 



