

164 MB, r. OUBEET ON A SPECIES 



filled with ripe spores. It is clear therefore that this purple skin 

 only forms as it were a partial veil, and cannot be properly looked 

 upon as a coat of the sporangium. Not unfrequently this skin 

 either partially peels off, of its own accord, or is imperfectly deve- 

 1( ped, as shown in fig. 7 ; but it usually hides the sporangium 

 entirely, and is finally cast off with it by the process peculiar to 

 the genus Pilobolus, namely the elastic action of the septum 

 which is formed at an early period across the upper end of the 

 vesicle between that and the sporangium. This septum takes an 

 upward growth, becomes gradually more and more everted, and at 

 length by its pressure throws off the sporangium-ceU and its pur- 

 ple veil to a distance of several inches. After this has taken place 

 the upper end of the stem-cell exhibits the appearance shown m 

 fig. 8. In the Transactions of the Breslau Academy for 1851 is 

 to be found an elaborate account of Pilobolus crystallinus by 

 Dr. Cohn, on reference to which it will be seen that the fungus 

 juBt described differs from Piloholus crystalliniis in the great de- 

 velopment in length of the stem, and the vast number of the drops 

 of water spread over its surface. There is another peculiarity, 

 which consists in a niunber of shining specks scattered over the 

 surface of the veil, having the appearance of small grains of 

 quartz ; but these, although very general, are not universal. They 

 are so minute that it is almost impossible to detach them sepa- 

 rately, and they do not occur in sufficient numbers on any one 

 plant to be capable of being scraped off in a mass. In one in- 

 stance they seemed to dissolve in water into a number of exceed- 

 ingly minute pear-shaped bodies ; but the observation was an 

 uncertain one, and beyond it I have not yet been able to ascertain 

 their nature. 



The distinctions above mentioned would not, I think, be alone 

 sufficient to separate this species from P. crystallinVrS, and I 

 should have been disposed to consider the present fungus as only 

 a form of the latter species, had it not been for a difference in the 

 spores. Such a difference, I need hardly say, is one of the safest 

 criterions for the separation of species in Fimgi, and one which 

 will probablv be more and more valued in nronortion as the mi- 



called 



Piloholus 



bular, smrounded by a tough distinct membrane, the latter ap- 

 pearing as a broad dark line, and fiUed with flesh-coloured, grumous 



refractive 



ents, with smaU nucleoli. Now the spores 

 are quite unlike those figured by Dr. Cohn ; 



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