118 Mr. A. H. Hassall on the Production of Diseases 



serted in the ' Annals ' for August 1843, caused me to consult Pro- 

 fessor Ehrenberg's * De Mycetogenesi Epistola.* 



The illustrious Professor of Berlin, after citing the various opinions 

 entertained by naturalists as to the nature of Fungi, proceeds to give 

 descriptions of certain species, together with the details of experi- 

 ments performed with the view of determining the fact of their de- 

 velopment from sporules or seeds. 



The first species which the Professor describes, " Ordeium Fructi- 

 gerum," he says, " springs up in putrid pears, apples, and plums in 

 whatsoever manner cultivation shall have changed these. The most 

 luxuriant crop usually proceeds from those apples which either hang 

 from the tree or lie upon the ground, premature decay having invaded 

 them. At 7 a.m. of the 20th day of August, I sowed the sporidia 

 of this fungus in a putrid pear so cut up as that it should show si- 

 milar plants wherever these were placed upon it. I thought more- 

 over, that if any germs could proceed out of the sporangia, that this 

 ought more readily to occur in a soil manifestly adapted to the nou- 

 rishment of these plants, and experience taught me that all fungi 

 would not grow in every putrid body. I performed the experiment 

 in the following manner : — 



" I cut up a pear, drew out with the moist point of a fine knife ap- 

 plied to the tufts of the fungi an abundance of sporidia, and deposited 

 them in some internal part of the putrid pear. In this manner I 

 placed many little heaps of sporidia near to each other, all being vi- 

 sible. I placed the pear in such a situation as that I could always 

 procure it, but it was deposited in high grass every dewy morning, 

 nor could it be touched by the sun. At 8 o'clock the next morning 

 I sought for the grains sown yesterday. I saw all the heaps with 

 the unaided sight shining as though adorned with silk, and some even 

 were subhirsute. I concluded that now the germs had come forth. 

 Immediately I removed with the point of a knife a small portion of 

 one of the clusters, and being placed in a drop of water on a piece of 

 glass, I separated it with the aid of two very fine knives. I saw the 

 germs of the sporidia increased in diameter about a hundred times, 

 and so distinct as that any one ought to be able to perceive them 

 readily who sought for them after my method." 



The above and other experiments with another fungus, Rhizopus 

 nigricans, conducted, as Ehrenberg especially tells us, in precisely the 

 same manner as the former, are the only ones which he performed 

 with the view of determining the development of fungi in connexion 

 with fruit. Now it is not a little curious to notice that the condition 

 of the fruit experimented on should be so particularly referred to in 

 the account, viz. that it was in a state of putridity or decay, as though 

 it were conceived that such a condition was a circumstance essential 

 to the development of the fungi ; the worthy Professor little imagi- 

 ning (as was most probably the case, for it is a rare thing for a fruit, 

 vegetable or flower to decay without the co-operation of fungi) that 

 the sporules which he was at so much pains to introduce existed al- 

 ready in the decayed fruit, and that his sections did little more than 

 present a direct way of egress to the filaments of the fungi. 



