338 The Fungus Disease of India. [part ii. 



debateable land between fungi and algae — aquatic fungi, Achlya^ Saprolegnia, and the 

 like — is of itself a question sufficiently difficult to occupy the undivided attention 

 of botanical experts for years to come, so that we do not consider it necessary to 

 offer any excuse for leaving such questions to those in whose province they lie and 

 restricting ourselves to their pathological bearing. We are the more inclined to this 

 course, as there are, unfortunately, only too many examples on record of the great 

 hindrance to the advancement of our knowledge of the causation of diseases which 

 has been occasioned by pathologists and botanists having trespassed on each other's 

 domains. This is an evil which it shall be our endeavour to avoid. 



It will be convenient for many reasons to restrict ourselves to the employment 

 of one term whilst describing the particular vegetations under discussion ; and as 

 it is only very rarely that what, in the present state of our knowledge, are 

 regarded as " algae " manifest truly parasitic proclivities, we shall refer to them as 

 " fungi " simply. 



The opinion that fungi are endowed with the power of inducing disease is not 

 an unnatural one, seeing that they are the most constant of all the attendants on 

 disease and decay. Their germs are known to be universally distributed, and were 

 it not for the peculiar conditions required for their development, their depredations 

 would be past conception. Fortunately nature has fixed a very potent barrier between 

 a sporule and the organized material upon which it may chance to settle, and 

 which, were it not for this barrier, it would speedily appropriate to its own use. 

 This barrier is healthy life. It has yet to be shown that the living matter of the 

 tissues of any animal, so long as it retains its vitality undiminished, is liable to 

 succumb to the attacks of a fungus. Should a spore be brought into contact with 

 bioplasm whose vitality is impaired, however, the changes in the latter which such 

 impairment implies may be of such a kind as to transform it into most suitable pabulum 

 for the nourishment of the former. The impairment of vitality may be due either 

 to disease or be a normal process, the result of age : whether the change be normal 

 or abnormal matters little to the fungus — it grows and multiplies wherever it finds 

 material exactly suited to it. 



It is the less vitalized portions of animals that are prone to epiphytic attacks — 

 portions which have little or no power of repair. Hence the epidermic tissues, the 

 wing covers and articular plates of flies and insects, branchial plates of fishes, and 

 the like, are the parts on which fungi are most commonly found. In such cases 

 the vegetable organisms do not attack the living material, but what has ceased to 

 undergo any active nutritive changes and is virtually dead, excreted material. With 

 regard to those instances in which it is known that fungi are associated with the 

 existence of disease during life, it is far from proven in any single case that the 

 disease was not present prior to the fungus. For example, it is most strongly 

 maintained by many observers that it is only the sickly silkworm that is ever attacked 

 by fungi, and that inoculation can only be effected after the worm has sickened. 



